Engineering tools
Circuits, signals, structures, machines and energy. 73 free tools, with no sign-up. Nothing you enter leaves your device.
Electrical and electronics 7
- Circuit simulatorType or paste a SPICE-style netlist of resistors, capacitors, inductors and voltage or current sources, then get the DC operating point, an AC sweep with the Bode magnitude and phase at any node, or the voltage against time with pulse, sine or piecewise sources. Nothing is uploaded. #621
- Resistor colour codeRead a resistor's colour bands (3 to 6 bands) as ohms, tolerance and temperature coefficient, or turn a value into its colour bands; find the nearest standard value in E6 to E192; and design a voltage divider from a pair of standard resistors with worst-case output, current and power. #622
- Analog filter designerDesign a low-pass or high-pass filter of order 1 to 12 with a Butterworth or Chebyshev response, built as unity-gain Sallen-Key op-amp stages, a passive LC ladder, or a single RC or RL. Get every part value, rounded to E-series, the pole frequency and Q of each stage, the order you need for a given cut, and a Bode plot of the exact and rounded designs. #623
- PCB trace width and impedanceWork out the minimum PCB trace width for a current and temperature rise with the IPC-2221 formula, with the trace's resistance, voltage drop and heat; and the characteristic impedance, effective permittivity and delay of a microstrip or stripline, or the width for 50 Ω. Millimetres or mils. #624
- Op-amp circuit calculatorWork out the gain of the classic op-amp circuits from their resistors and capacitors, the real bandwidth from the op-amp's gain-bandwidth product, the output swing and clipping on your supply, slew-rate limits, and the common-mode rejection of a difference amplifier, with a Bode plot and the input and output waveforms. #625
- LED resistor calculatorWork out the series resistor for one LED or a string of LEDs, pick the standard E12, E24 or E96 value, see the resistor and LED power with a safe resistor rating, how much the current moves with forward-voltage spread and supply tolerance, and plan an array of many LEDs as even strings with a power budget. #626
- Battery runtime and solar sizingHow long will a battery run a load, with converter efficiency, usable depth of discharge and the Peukert effect? And what does an off-grid solar system need: list your appliances to get the daily load, solar array size and number of panels, battery bank in Wh and Ah with a series and parallel layout, and the charge controller current. #627
Signal processing 4
- FFT workbenchPaste or open a signal (time and value, or values and a sample rate) and get its amplitude or power spectrum with a Hann, Hamming, Blackman or no window, a list of peaks, and a simple FFT low-, high- or band-pass filter back to time. CSV downloads; nothing is uploaded. #628
- FIR/IIR filter designerDesign a low-pass, high-pass, band-pass or band-stop digital filter: FIR by the window method (Hamming, Hann, Blackman, Kaiser) or IIR Butterworth and Chebyshev type I by the bilinear transform. See the gain, phase and group delay, the poles and zeros, and copy the coefficients as C arrays, second-order sections or CSV. #629
- Sampling and aliasing explorerType a signal frequency and a sample rate and see what the samples really record: the apparent (alias) frequency, the Nyquist zone, the alias sine drawn through the samples, a folding diagram and the ideal sinc reconstruction. Includes the wagon-wheel effect and audio examples. #630
- Wavelet transform viewerPaste or open a signal and see which frequencies are present at each moment with a continuous Morlet wavelet scalogram, and split it into detail and approximation levels with a Haar or Daubechies discrete wavelet transform. Matches PyWavelets; CSV downloads; nothing is uploaded. #631
RF and communications 3
- Antenna calculatorWork out antenna sizes from the frequency: half-wave dipole and quarter-wave monopole lengths, a rectangular microstrip patch (width, effective permittivity, fringing length, edge resistance and inset feed) and a starting Yagi-Uda layout, with every formula shown. #632
- Smith chartPlot a load impedance on an interactive Smith chart and get the reflection coefficient, VSWR, return loss and mismatch loss, the impedance after any length of line, both L-network matching solutions with part values, and single open or shorted stub matching. #633
- Modulation and BER simulatorSend Gray-coded BPSK, QPSK, 8-PSK, 16-QAM or 64-QAM symbols through seeded white Gaussian noise at your Eb/N0 and see the noisy constellation. Count the bit and symbol errors with a 95 % interval and compare them with the theoretical rates. Sweep Eb/N0 to plot the simulated bit error rate against the theory curves of all five schemes, and download the sweep as CSV. #634
Control and robotics 6
- D-H forward kinematicsType a robot arm's Denavit-Hartenberg table (standard or modified convention), move the joints with sliders and get every link transform, the end-effector position and orientation (roll, pitch, yaw, quaternion), the Jacobian and a 3D picture you can turn. Nothing is uploaded. #635
- PID tuning simulatorPick a plant (first or second order, or any transfer function) with dead time, set the PID gains with sliders and see the closed-loop step response with rise time, overshoot, settling time and steady-state error, the controller output, the Bode plot with gain and phase margins, and Ziegler-Nichols starting values. Nothing is uploaded. #636
- Inverse kinematics for 2 and 3 link armsFind the joint angles that put a planar 2-link arm's tip, or a 3-link arm's tool at a given angle, on a target point. Both elbow-up and elbow-down solutions, a reach check that says why a point is out of reach, optional joint limits, a drawing of the arm and its workspace, and a batch of targets to CSV. #637
- State space and pole placementEnter the state-space matrices A, B, C and D to get controllability and observability (matrices and ranks), the open-loop eigenvalues, the state-feedback gain K that places your chosen poles (Ackermann), an observer gain L by duality, and the closed-loop step response. Nothing is uploaded. #638
- Kalman filter playgroundTry a Kalman filter in your browser. Simulate a noisy sensor with a repeatable seed or paste your own measurements, pick a constant-level or constant-velocity model, move the Q and R sliders, and watch the estimate against the truth, the innovations, the uncertainty and the gain. Download every step as CSV. #639
- Path planning visualiserDraw walls on a grid with a tap or a drag, then watch A* or Dijkstra (4 or 8 directions) find the shortest path and which cells they search, or grow a seeded RRT tree through open space. Shows path length, cells expanded and tree size, and downloads the path as CSV. #640
Mechanical engineering 8
- Beam deflection calculatorSolve a simply supported, cantilever, fixed-fixed, propped, overhanging or continuous beam under any mix of point loads, uniform or sloping distributed loads and applied moments. Get the support reactions, shear force and bending moment diagrams, the deflected shape and largest deflection, and the bending and shear stress for a rectangle, round bar or tube, I-beam built from plates, or your own I and c. #641
- Bolt preload and torqueWork out the tightening torque for a target bolt preload (or the preload a torque gives) with the nut factor T = K F d or the thread and under-head friction split, the tensile stress area of ISO metric or UNC/UNF threads from the pitch, the bolt and clamped-part stiffness, the joint constant, the separation load and safety factors, with a joint diagram. #642
- Gear train and belt driveWork out the speeds, directions, torques and power of each shaft in a simple, idler or compound gear train with mesh efficiencies and centre distances; solve a planetary gear set with the Willis equation (any member held or driven, assembly checks, torque split); and find the belt length, wrap angles and driven speed of an open or crossed belt drive, or the centre distance for a belt length. #643
- Spring designerDesign a round-wire helical spring. Compression: rate, Wahl-corrected shear stress, solid height and force for four end types, buckling limit and surge frequency. Extension: initial tension, hook bending and torsion stresses. Torsion: rate per turn and per degree, bending stress and the coil diameter under load. You enter the material values; examples are labelled. #644
- Shaft and bearing lifeWork out a rolling bearing's L10 life in revolutions and hours from its rating C and the equivalent load P = X Fr + Y Fa (your catalogue values), adjusted for reliability and aISO, or the C you need for a target life. Size a solid round shaft for combined bending and torsion in fatigue (DE-Goodman with your endurance limit) and statically (von Mises and maximum shear), or check the safety factors of a given diameter. #645
- Tolerance stack-upAdd up a chain of dimensions with plus and minus tolerances and directions to find the gap: worst case, root sum of squares (RSS) and a seeded Monte Carlo simulation with normal, uniform or triangular parts. Get the share of variance from each part, the fraction of assemblies outside the gap limits, and Cp and Cpk, with a histogram. Paste the chain or open a CSV or Excel file. #646
- Heat exchanger sizingSize or rate a heat exchanger: counterflow, parallel flow, shell and tube with 1 to 8 shell passes, or crossflow with either fluid mixed or unmixed. Get the duty, outlet temperatures, effectiveness, NTU, LMTD, the 1-2 shell-and-tube F factor and the area from U, with effectiveness-NTU curves and temperature profiles. #647
- 2D truss and frame solverType or paste the nodes, members, supports and loads of a plane truss or frame and solve it by the direct stiffness method: truss member forces in tension or compression, frame axial forces, shears and moments, support reactions, node displacements and a drawing of the deflected shape, with CSV downloads. #648
Civil and structural engineering 6
- Concrete mix calculatorWork out cement, water, sand and stone per cubic metre and per batch by the absolute volume method, from your own w/c ratio, water, air, coarse aggregate fraction, specific gravities and stockpile moisture. Corrects the batch for wet or dry aggregate and gives the target mean strength f'c + k·s. #649
- Rebar quantity and weightCount the reinforcing bars at your spacing over a slab, wall or footing, split long bars into stock lengths with your lap length, and get the total length, the weight from the steel density, the stock bars to order and a cut list to download. #650
- Load combination helperType your load cases (dead, live, snow, wind, earthquake and more) with their forces or moments, and your own load combinations with factors. The tool works out every combination, tries both directions of wind and earthquake, and shows the largest and smallest value of each effect and where it comes from. #651
- Column buckling calculatorWork out the buckling load of a straight column from its section (I or H, rectangle, solid circle or round tube), length, end conditions and material: section properties, slenderness KL/r, Euler's critical load for slender columns and the Johnson parabola for intermediate ones, with a column curve and an optional load check. #652
- Retaining wall stabilityCheck a cantilever or gravity retaining wall for sliding, overturning and bearing: Rankine or Coulomb active pressure, sloping backfill, surcharge, water and uplift, optional passive resistance, eccentricity and toe and heel pressures, with a drawing of the wall, the earth pressure and the bearing pressure. #653
- Road gradient and curve helperWork out the smallest safe radius for a speed from your superelevation and side friction, the elements and chainages of a circular curve with a setting-out table, the stopping sight distance, and the length of a crest or sag vertical curve from sight distance or K, with its levels, high or low point and a profile plot. #654
Geotechnical engineering 5
- Soil classification (USCS, AASHTO)Classify a soil from lab data. Paste a grading curve or type the key percentages, add the liquid and plastic limits, and get the USCS group symbol and name with every step explained, the AASHTO group and group index, D10, D30, D60, Cu and Cc, a grading curve and a plasticity chart. #655
- Bearing capacity calculatorUltimate and allowable bearing capacity of a shallow footing by Terzaghi, Meyerhof and Hansen, with the factors Nc, Nq and Nγ from their formulas, shape and depth factors, a water table correction, gross or net factor of safety and the allowable load, plus a side-by-side comparison. #656
- Consolidation settlement and timePrimary consolidation settlement of layered clay under a wide fill or a footing, for normally and over-consolidated layers, and how long it takes: Terzaghi's degree of consolidation from its series, time to any percent, a settlement-time curve, isochrones and cv from a lab t50 or t90. #657
- Slope stability (Bishop simplified)Factor of safety of a simple soil slope on circular slip surfaces by Bishop's simplified method (iterated) and the ordinary method of slices, with one or two soil layers, a pore pressure ratio ru or a water table, a grid search for the critical circle, a drawing and a slice table. #658
- Atterberg limits and compaction curveLiquid limit from a Casagrande flow curve or the one-point method, plastic limit, plasticity, liquidity and consistency indices and activity; and the Proctor compaction curve: dry density, a fitted curve with maximum dry density and optimum water content, zero-air-voids and air-voids lines and relative compaction. #659
Thermal and fluid engineering 4
- Pipe network pressure dropWork out the head loss and pressure drop in a pipe with the Darcy-Weisbach equation, the Colebrook-White or Swamee-Jain friction factor and minor losses (K), or the flow a given head will push. Then solve a looped pipe network with reservoirs, tanks and demands by Newton's method or Hardy Cross, with flows, velocities, head losses and pressures at every node. #660
- Steam tables and Rankine cycleLook up water and steam properties from pressure and temperature, saturation by pressure or temperature, or from pressure with enthalpy, entropy or quality, using the IAPWS-IF97 industrial formulation. Then work out a simple or reheat Rankine power cycle: turbine and pump work, heat in, thermal efficiency, exit quality, steam rate and a temperature-entropy diagram. #661
- Pump and system curveFit a pump curve to points read off the maker's chart, build the system curve from static head and pipe friction, and find the operating point with its efficiency and power. Try pumps in parallel or series, a new speed or a trimmed impeller (affinity laws), and check NPSH available against NPSH required. #662
- Room heating and cooling loadEstimate the peak heating and cooling load of a room from its walls, windows and roof (U-values), sun through the glass, air leakage and ventilation (sensible and latent), and the heat from people, lighting and equipment. Results in watts, BTU per hour and tons of refrigeration, with a breakdown. A simplified estimate, not a full ASHRAE or CIBSE method. #663
Chemical engineering 5
- McCabe-Thiele calculatorStep off the theoretical stages of a binary distillation column on a McCabe-Thiele diagram, from a relative volatility or your own x-y data. Gives minimum reflux (including tangent pinches), Fenske minimum stages, the best feed stage, real trays and column flows. #119
- Vapour pressure and VLE calculatorWork out vapour pressure and boiling point from Antoine constants, then the bubble and dew points, flash split, relative volatility and Txy and xy diagrams of an ideal two-component mixture (Raoult's law). #120
- Mass and energy balance solverDescribe a process flowsheet in a few lines (mixers, splitters, separators with split fractions, reactors with a conversion) and its feeds, and get every stream's component flows, a degrees-of-freedom check, a stream table and, with heat capacities, the temperatures and heat duties. Recycle loops are solved directly as one linear system. #664
- Reactor design: CSTR, PFR and batchSize an isothermal CSTR, plug flow reactor, train of equal CSTRs or batch reactor for a target conversion, or find the conversion a given size reaches. n-th order, reversible first-order and saturating rate laws, an Arrhenius rate constant, gas-phase volume change, a Levenspiel plot and conversion-volume curves. #665
- Heat of reaction and adiabatic temperature riseType the species of a reaction with their heats of formation and heat capacities, the feed and the conversion, and get the heat of reaction at any temperature (Kirchhoff), the adiabatic outlet or flame temperature (with excess reactants and diluents), a quick ΔT estimate, the energy released per kg, and charts against conversion and temperature. #666
Aerospace engineering 5
- Standard atmosphere calculatorGet the temperature, pressure, density, speed of sound, viscosity and gravity of the 1976 US Standard Atmosphere (the ISA) at any height from −5 to 86 km, with an ISA deviation, the pressure altitude for a pressure, the density altitude at an airfield, and a table and plots you can download. #667
- Aircraft performance calculatorFrom the mass, wing, drag polar (CD0 and Oswald e) and engine, get the best lift-to-drag ratio, stall speed, the speeds for least drag and least power, Breguet range and endurance for jets and propeller aircraft, and a take-off ground roll, with drag and power curves. #668
- Propeller and rotor thrustWork out a rotor's static thrust from its shaft power (or the power for a thrust) with actuator-disc momentum theory and a figure of merit, the induced velocity, disc and power loading, a figure of merit from a test, and a blade element momentum model of your own propeller with thrust, torque, efficiency and CT and CP against advance ratio. #669
- Model rocket flight simulatorPaste or open a motor thrust curve (or pick a made-up shape), give the rocket's mass, diameter and drag coefficient, and get a straight-up flight: apogee, top speed and Mach number, speed off the rod, burnout, the best ejection delay, and plots of altitude, velocity and thrust. #670
- Drone flight time calculatorFrom the all-up weight, propeller size and battery, estimate a multirotor's hover power and flight time with momentum theory (or from your measured hover current), the time and range at a cruise speed, the speeds for the longest flight and the longest range, current draw, C-rate and thrust-to-weight. #671
Energy and power systems 5
- Solar PV yield estimatorGive a place, the panels' tilt and direction, the system size and losses, and get an hour-by-hour clear-sky year (sun position, Haurwitz clear sky, Erbs split, isotropic sky on the tilted panels), scaled by your own sunshine estimate: yearly and monthly energy, specific yield, capacity factor and the best tilt. #672
- Wind turbine energy yieldPaste or open wind speed readings (or give Weibull k and c, or a mean speed), correct them to hub height with the power or log law, adjust for air density, and combine with a power curve to get the annual energy production, capacity factor, full-load hours and energy by wind speed. #673
- Load flow for small networksType or open bus and line tables, and solve the AC power flow in per unit by Newton-Raphson or Gauss-Seidel. Get every bus voltage and angle, line flows at both ends, losses and a single-line diagram. Nothing is uploaded. #674
- Home battery storage sizingSimulate a home battery hour by hour with your load and solar data (or a made-up template year), sweep battery sizes, and see self-consumption, grid import and export, cycles, backup hours and a recommended size. Nothing is uploaded. #675
- Levelised cost of energy (LCOE)Work out the levelised cost of energy of a solar, wind, gas or any other plant from capital cost, fixed and variable O&M, fuel, output loss, discount rate, lifetime and capacity factor, with a yearly cash-flow table, a cost breakdown and a tornado chart. Nothing is uploaded. #676
Nuclear engineering 3
- Reactor point kinetics simulatorSimulate how a reactor's power responds to a step or ramp of reactivity with the six-group point kinetics equations, solved with a stiff implicit method. See the prompt jump, the stable period from the inhour equation, and scrams. For study. Nothing is uploaded. #677
- One-group diffusion and criticalityWork out the geometric buckling, k_eff and critical size of a bare slab, sphere, cylinder or box from one-group (or two-group) diffusion data, see the flux shape, and check the formula with a numeric finite-volume solve. For study. Nothing is uploaded. #678
- Decay heat estimatorEstimate the heat a reactor core still makes after shutdown with the Way-Wigner approximation: a table from seconds to a year, energy released over any interval, and when the heat falls below a level. An approximation, for study. Nothing is uploaded. #679
Biomedical engineering 3
- ECG viewer and HRVOpen or paste a single-lead ECG, filter it, find the beats with the Pan-Tompkins method and get heart rate, an RR tachogram, time-domain HRV (SDNN, RMSSD, pNN50), a Lomb-Scargle spectrum with LF and HF power, and a Poincaré plot. For study and research, not for diagnosis. Nothing is uploaded. #680
- EMG envelope and fatigue analyserOpen or paste a surface EMG recording, band-pass and rectify it, get a moving RMS or low-pass envelope, find each contraction's onset and offset from a rest threshold, and follow muscle fatigue as the median and mean frequency fall in sliding Welch windows, with the slope. For study and research, not for diagnosis. Nothing is uploaded. #681
- Drug release curve fitterPaste cumulative drug release against time and fit the six classic release models at once, with parameters and their errors, R², adjusted R², AIC, the best model and what the Korsmeyer-Peppas exponent n says about the mechanism. Also fits first-order mass loss of a degrading biomaterial, with its half-life. Release kinetics only, no doses. #682
Transportation engineering 2
- Traffic flow fundamentalsPaste speed and density (or flow) observations and fit the Greenshields, Greenberg and Underwood models: free-flow speed, jam density, capacity, the speed-density, flow-density and speed-flow diagrams, and an operating point with level of service from density limits you enter. For study and planning. #683
- Signal timing (Webster's method)Enter each approach's phase, flow and saturation flow to get the critical flow ratios, total lost time, Webster's optimum cycle C0 = (1.5L + 5)/(1 − Y), effective and displayed greens, capacity, degree of saturation and Webster delay for every approach, with a timing diagram and a delay-against-cycle curve. For study and planning. #684
Petroleum engineering 3
- Decline curve analysis (Arps)Paste or open a well's rate-time history, fit Arps exponential, hyperbolic and harmonic declines by least squares, and forecast to the economic limit with EUR, remaining reserves, an optional terminal decline, and plots on linear and log axes. #686
- Oil and gas PVT correlationsEstimate black-oil and natural gas properties from API gravity, gas gravity, GOR, temperature and pressure: Standing and Vasquez-Beggs bubble point, Rs and Bo, Beggs-Robinson viscosity, Z-factor by Dranchuk-Abou-Kassem or Hall-Yarborough with Sutton pseudo-criticals, Bg, gas density and Lee-Gonzalez-Eakin viscosity, with curves against pressure. #687
- Pressure buildup analyserPaste or open shut-in pressures from a buildup test and get permeability, skin, p*, the pressure drop from skin and the radius of investigation from a Horner or MDH straight line (picked automatically or by you), with a log-log Bourdet derivative plot to spot wellbore storage, radial flow and boundaries. #688
Metrology and quality 4
- Gauge R&R studyPaste or open a crossed gauge study (parts × operators × trials) and get repeatability, reproducibility, %GRR of study variation and tolerance, % contribution and the number of distinct categories by the ANOVA method and the average and range method, with the ANOVA table and R, X-bar and interaction charts. #689
- Control charts and process capabilityPaste or open process data and draw X̄-R, X̄-S, I-MR, p, np, c or u control charts with limits from your data, Western Electric or Nelson rule flags, and process capability (Cp, Cpk, Pp, Ppk with confidence intervals, expected ppm) with a histogram and normal fit. #690
- Calibration interval and drift trackerPaste or open an instrument's calibration history (date, as-found error, uncertainty) and get the drift rate by regression with its confidence interval, a prediction band, the date the error is expected to reach the tolerance limit, and a calibration interval that meets your reliability target, with optional guard banding. #691
- Engineering unit converterConvert between SI, metric and US/imperial units for length, area, volume, mass, force, pressure, energy, power, temperature, flow, viscosity, density, torque, heat transfer and more, or type any expression such as 3 kN*m to lbf*ft and get the answer with a dimension check that catches impossible conversions. #692
No engineering tool matches that yet. Try the search on the home page, or suggest it.