75+ free engineering Tools, one tab away
Sizing a cable, checking a beam, decoding a resistor, tuning a PID loop or just crunching numbers — the working tools engineering students and practising engineers reach for, with the standard shown next to every answer.
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Students' toolkit
Fast, formula-first tools for assignments, labs and viva prep.
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Standards-based calculators for design checks, estimation and field decisions.
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Cable Size Calculator
Size conductors from load current using ampacity, derating factors and voltage-drop limits.
Open tool : Cable Size CalculatorHome Load Calculator
Add up household appliances, then size your inverter, battery bank and rooftop solar array.
Open tool : Home Load CalculatorTransformer Calculator
Full-load current, short-circuit current, regulation and parallel-operation checks for any kVA rating.
Open tool : Transformer CalculatorVoltage Drop Calculator
Check DC, single-phase and three-phase drop against the usual 3% and 5% limits.
Open tool : Voltage Drop CalculatorRelay Coordination Tool
Plot IEC 60255 IDMT curves, verify CTI margins and grade upstream against downstream relays.
Open tool : Relay Coordination ToolElectrical Symbol Finder
Search 60+ IEC circuit symbols by name or function and download each one as clean SVG.
Open tool : Electrical Symbol FinderTransformer Sizing Calculator
Size the feeding transformer for motor loads with starting inrush and safety margins.
Open tool : Motor-to-Transformer Sizing CalculatorOhm's Law Calculator
Solve voltage, current, resistance and power from any two known values instantly.
Open tool : Ohm's Law CalculatorResistor / Capacitor / Inductor Color Code Calculator
Decode 4, 5 and 6-band resistors plus capacitor and inductor codes, with tolerance.
Open tool : Resistor / Capacitor / Inductor Color Code CalculatorAntenna Length Calculator
Size dipole, monopole, ground-plane and Yagi elements for any frequency and velocity factor.
Open tool : Antenna Length CalculatorLogic Gate Truth Table Generator
Build truth tables, simplify Boolean expressions and read Karnaugh maps for four variables.
Open tool : Logic Gate Truth Table GeneratorOp-Amp Gain / Filter Designer
Design inverting, non-inverting and active filter stages with GBW and slew-rate checks.
Open tool : Op-Amp Gain / Filter DesignerPCB Trace Width Calculator
IPC-2221 trace width, temperature rise, resistance and via current capacity for any layer.
Open tool : PCB Trace Width CalculatorSubnet Calculator (CIDR)
Network address, broadcast, usable host range and mask conversion for any IPv4 CIDR block.
Open tool : Subnet Calculator (CIDR)IP Address Class Finder
Identify class A to E, default mask, and whether an address is private or reserved.
Open tool : IP Address Class FinderNumber Base Converter
Convert between binary, octal, decimal, hexadecimal and any custom base instantly.
Open tool : Number Base ConverterPassword Strength Checker
Estimate entropy and crack time, and see exactly which rules a password passes or fails.
Open tool : Password Strength CheckerRegex Tester & Builder
Test patterns against sample text offline, with match highlighting and a plain breakdown.
Open tool : Regex Tester & BuilderBig-O Complexity Estimator
Compare growth rates and estimate operation counts for common algorithms at any size.
Open tool : Big-O Complexity EstimatorGear Ratio Calculator
Up to five gear stages with idlers, efficiency losses, output torque and an SVG diagram.
Open tool : Gear Ratio CalculatorBelt & Pulley Speed Calculator
Driven speed, belt length, wrap angle and slip check for open and crossed belt drives.
Open tool : Belt & Pulley Speed CalculatorShaft Diameter Calculator
Size solid or hollow shafts under combined torque and bending, with angle-of-twist check.
Open tool : Shaft Diameter CalculatorSpring Design Calculator
Spring rate, Wahl-corrected stress, solid height and surge frequency for helical springs.
Open tool : Spring Design CalculatorBearing Life (L10) Calculator
ISO 281 rating life in revolutions, hours and years from load rating and speed.
Open tool : Bearing Life (L10) CalculatorConcrete Mix Design Calculator
IS 10262 mix design for M20 to M40 with cement, sand and aggregate quantities.
Open tool : Concrete Mix Design CalculatorBar Bending Schedule Generator
IS 2502 cutting lengths, bend deductions, hook allowances and total steel weight.
Open tool : Bar Bending Schedule GeneratorBeam Deflection Calculator
Point load and UDL deflection with a span/250 check and live bending and shear diagrams.
Open tool : Beam Deflection CalculatorColumn Design Load Calculator
IS 456 axial capacity, slenderness classification and reverse sizing for short columns.
Open tool : Column Design Load CalculatorBrick / Block Quantity Estimator
Bricks, cement bags, sand volume and total wall cost from your wall dimensions.
Open tool : Brick / Block Quantity EstimatorChemical Dilution Calculator
Solve C1V1 = C2V2 for any unknown and get the exact stock and diluent volumes.
Open tool : Chemical Dilution CalculatorMolarity / Normality Calculator
Convert between mass, moles, molarity and normality for any solute and volume.
Open tool : Molarity / Normality CalculatorReynolds Number Calculator
Classify pipe flow as laminar, transitional or turbulent from velocity and viscosity.
Open tool : Reynolds Number CalculatorpH Calculator (Acid-Base)
Find pH, pOH and hydrogen ion concentration for strong and weak acids and bases.
Open tool : pH Calculator (Acid-Base)Distillation Column Basic Sizing
McCabe-Thiele lite: minimum reflux, theoretical stages and first-pass column height.
Open tool : Distillation Column Basic SizingLift & Drag Coefficient Calculator
Derive Cl and Cd from lift, drag, wing area and dynamic pressure, then read L/D.
Open tool : Lift & Drag Coefficient CalculatorRocket Equation (Tsiolkovsky) Calculator
Tsiolkovsky delta-v from mass ratio and specific impulse, with propellant breakdown.
Open tool : Rocket Equation (Tsiolkovsky) CalculatorMach Number Calculator
Mach number and flow regime from true airspeed, altitude and local speed of sound.
Open tool : Mach Number CalculatorWing Loading Calculator
Wing loading, stall speed and thrust-to-weight for fixed-wing aircraft and UAV designs.
Open tool : Wing Loading CalculatorOrbital Velocity Calculator
Circular orbital velocity, period and escape velocity for any altitude around any body.
Open tool : Orbital Velocity CalculatorEV Battery Range Estimator
Estimate real-world range from pack capacity, consumption, payload and driving style.
Open tool : EV Battery Range EstimatorFuel Efficiency (Mileage) Calculator
Convert between kmpl, mpg and L/100 km, and work out trip fuel cost from distance.
Open tool : Fuel Efficiency (Mileage) CalculatorEngine Power / Torque Converter
Convert HP, kW, BHP and Nm at any engine speed, with a torque-power relationship view.
Open tool : Engine Power / Torque ConverterBraking Distance Calculator
Reaction plus braking distance from speed, friction, road grade and reaction time.
Open tool : Braking Distance CalculatorEV Charging Time Estimator
Charging duration from pack size, state of charge, charger power and efficiency.
Open tool : EV Charging Time EstimatorOEE Calculator
Overall equipment effectiveness from availability, performance and quality, with benchmarks.
Open tool : OEE CalculatorEconomic Order Quantity (EOQ) Calculator
Optimal order size, reorder point and total inventory cost from demand and cost inputs.
Open tool : Economic Order Quantity (EOQ) CalculatorLine Balancing Efficiency Calculator
Cycle time, minimum stations, balance delay and line efficiency for assembly lines.
Open tool : Line Balancing Efficiency CalculatorInventory Carrying Cost Estimator
Annual carrying cost as a percentage of inventory value, split by each cost driver.
Open tool : Inventory Carrying Cost EstimatorMachine Cycle Time Estimator
Cycle time, throughput per shift and takt comparison from setup, run and handling times.
Open tool : Machine Cycle Time EstimatorPID Controller Tuning Estimator
Ziegler-Nichols and Cohen-Coon gains from step response or ultimate gain and period.
Open tool : PID Controller Tuning EstimatorSensor Range / Accuracy Converter (4-20 mA)
Convert between 4-20 mA, 0-10 V and engineering units, with the error band at any point.
Open tool : Sensor Range / Accuracy Converter (4-20 mA)Control Valve Cv Sizing Calculator
Flow coefficient Cv and Kv for liquid service, with choked-flow and pressure-drop checks.
Open tool : Control Valve Cv Sizing CalculatorInstrument Air Consumption Estimator
Total plant instrument-air demand from valve and positioner counts and duty cycle.
Open tool : Instrument Air Consumption EstimatorSignal Loop Wiring Calculator
Loop resistance budget, maximum cable length and compliance voltage for a 4-20 mA loop.
Open tool : Signal Loop Wiring CalculatorCarbon Footprint Calculator
Annual CO2 footprint from electricity, fuel, travel and waste in one place.
Open tool : Carbon Footprint CalculatorRainwater Harvesting Tank Size Calculator
Size a storage tank from roof catchment area, local rainfall and daily demand.
Open tool : Rainwater Harvesting Tank Size CalculatorWater Treatment Dosing Calculator
Coagulant, chlorine and lime dose plus daily chemical demand for a treatment plant.
Open tool : Water Treatment Dosing CalculatorBOD / COD Estimator
Estimate BOD, COD and their ratio to gauge how biodegradable a wastewater is.
Open tool : BOD / COD EstimatorSolid Waste Generation Estimator
Daily and annual municipal solid-waste load from population and per-capita rate.
Open tool : Solid Waste Generation EstimatorBlast Hole Pattern Calculator
Burden, spacing, powder factor and charge per hole for a surface blast pattern.
Open tool : Blast Hole Pattern CalculatorDrilling Mud Weight Calculator
Mud weight, hydrostatic pressure and equivalent circulating density for a well.
Open tool : Drilling Mud Weight CalculatorOre Grade / Tonnage Estimator
Contained metal and recoverable tonnage from ore grade, volume and recovery rate.
Open tool : Ore Grade / Tonnage EstimatorReservoir Volume Estimator (OOIP)
Original oil in place from area, net pay thickness, porosity and water saturation.
Open tool : Reservoir Volume Estimator (OOIP)Wellhead Pressure Converter
Convert wellhead pressure across psi, bar, kPa and mud-weight gradient.
Open tool : Wellhead Pressure ConverterBMI + Medical Dosage Unit Converter
Body mass index, body surface area and weight-based dosage for clinical calculations.
Open tool : BMI + Medical Dosage Unit ConverterDNA / RNA Codon Translator
Translate DNA or RNA sequences into amino acids with reading-frame options.
Open tool : DNA / RNA Codon TranslatorECG Signal Sampling Rate Calculator
Nyquist-safe sampling rate, storage size and aliasing check for ECG and biosignals.
Open tool : ECG Signal Sampling Rate CalculatorIrrigation Water Requirement Calculator
Crop water requirement from evapotranspiration, crop coefficient, rainfall and efficiency.
Open tool : Irrigation Water Requirement CalculatorCrop Yield Estimator
Expected yield per hectare from plant density, grains per head and grain weight.
Open tool : Crop Yield EstimatorTractor / Farm Machinery Power Calculator
Tractor drawbar power, PTO requirement and implement matching from draft and speed.
Open tool : Tractor / Farm Machinery Power CalculatorScientific Calculator
Full scientific calculator with trig, logs, powers, memory and radian or degree modes.
Open tool : Scientific CalculatorPercentage Calculator
Percentage of a number, percentage change and reverse-percentage, all in one place.
Open tool : Percentage CalculatorEngineering Unit Calculator
Convert across length, mass, pressure, power, flow and dozens more unit families.
Open tool : Engineering Unit CalculatorPower Calculator
Raise numbers to any power, take roots and read scientific-notation results instantly.
Open tool : Power CalculatorNo tool matches that yet
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Every calculator here is free. No trial, no credit card, no paywalled results.
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Built by a practising engineer
Each module ships with the real formula, not a rounded shortcut, checked against worked examples.
Standards-based
Results follow IS 456, IS 10262, IEC 60255, ISO 281 and IPC-2221 wherever a standard applies.
75+ free engineering tools. Zero paywalls, zero signups.
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