Free Engineering Calculators

Voltage Divider Calculator

Calculate output voltage from a resistor voltage divider circuit using Vout = Vin × R2/(R1+R2).

Gear Ratio Calculator | RPM, Torque & Trains

Calculate gear ratio, output RPM, torque multiplier, and speed change for simple gear pairs and multi-stage gear trains. Visual SVG diagram included.

Beam Deflection Calculator

Calculate maximum deflection and slope for cantilever, simply supported, and fixed-fixed beams with section presets, material library, and serviceability code checks.

Pipe Flow Calculator | Darcy-Weisbach

Calculate fluid flow rate, velocity, and pressure drop in pipes using the Darcy-Weisbach equation.

Power Factor Calculator | AC Circuit

Calculate power factor, real power, reactive power, and apparent power for AC circuits.

Resistor Series & Parallel Calculator

Calculate equivalent resistance for resistors in series, parallel, or mixed configurations. Add or remove resistors dynamically and see the result instantly.

Concrete & Cement Calculator

Calculate concrete volume for slabs, footings, walls, columns, and circular pads. Shows bags needed (25 kg, 40 kg, 60 lb, 80 lb), cubic yards, and optional cost estimate.

Wire Gauge Calculator | AWG, Current & Resistance

Look up AWG wire gauge specs: current-carrying capacity (ampacity), resistance per foot, voltage drop, and cross-sectional area. Calculate wire size from current load and find safe circuit wire length.

Battery Life Calculator | Runtime & Charge Cycles

Estimate battery runtime from capacity (mAh/Wh) and current draw. Calculate charge cycles to 80% capacity, find the right battery size for your device, and compare battery packs.

Electricity Cost Calculator | Home Energy & Appliance Usage

Calculate the electricity cost of any appliance or entire home. Add multiple devices with wattage and daily hours, set your kWh rate, and get daily, monthly, and annual costs with CO₂ emissions and a ranked consumption breakdown.

Solar Panel Calculator | ROI, Payback & 25-Year Savings

Estimate solar panel energy production, annual savings, payback period, and 25-year net savings. Accounts for system size, local sun hours, electricity rate, installation cost, federal tax credit, and annual electricity price escalation.

Voltage Drop Calculator | NEC Wire Sizing & Circuit Compliance

Calculate voltage drop percentage for single-phase and three-phase AC circuits. Checks compliance with NEC 3% branch-circuit and 5% total-circuit limits, recommends the minimum wire gauge (AWG) to meet code, and supports both copper and aluminum conductors.

Fence Calculator | Posts, Panels, Concrete & Material Estimator

Calculate the exact number of fence posts, panels or boards, concrete bags, and total materials for any fencing project. Supports wood privacy, picket, split-rail, chain-link, and vinyl styles with custom gate placement and per-unit cost estimation.

Tile Calculator | How Many Tiles Do I Need?

Calculate the exact number of tiles needed for any floor, wall, or backsplash project. Accounts for waste percentage, grout width, tile orientation, and cut tiles at borders. Supports square, rectangular, and custom tile sizes with cost estimation per box or sheet.

Roof Calculator | Shingles, Squares & Roofing Materials

Calculate roofing squares, shingles, bundles, felt underlayment, ridge cap, and starter strips for any roof shape. Enter footprint dimensions and pitch to get complete material quantities with a configurable waste factor for hips, valleys, and cuts.

Deck Calculator | Boards, Joists, Posts & Material Estimator

Calculate deck boards, joists, posts, concrete footings, rim boards, and hardware for any wood or composite deck. Enter dimensions, board width, and joist spacing — with diagonal board options and a complete material summary with optional cost estimate.

Mulch Calculator | Cubic Yards, Bags & Landscaping Coverage

Calculate the exact cubic yards or number of bags of mulch, topsoil, gravel, or compost needed for any garden bed, lawn area, or landscaping project. Supports multiple shapes — rectangular, circular, and triangular — with bulk vs bagged cost comparison.

Carbon Footprint Calculator | Personal CO₂ Emissions Estimator

Estimate your annual personal carbon footprint across four major categories: home energy use, transportation, diet and food, and consumer spending. Shows total CO₂ equivalent in metric tons, comparison to US and global averages, biggest contributor breakdown, and practical reduction actions.

RLC Circuit Calculator | Resonance, Impedance & Q Factor

Analyze series and parallel RLC circuits. Computes resonant frequency, impedance at any input frequency, damping ratio, Q factor, bandwidth, and phase angle. Classifies the circuit as overdamped, critically damped, or underdamped and shows the time-domain step response type.

Stress-Strain Calculator | Young's Modulus, Poisson's Ratio & Deformation

Calculate normal stress, axial strain, lateral strain, shear stress, shear strain, and deformation for structural members under axial or shear loading. Includes Young's modulus, shear modulus, and bulk modulus with material presets for steel, aluminum, concrete, copper, and rubber. Computes safety factor against yield.

LMTD Calculator | Log Mean Temperature Difference & Heat Exchanger Design

Calculate the log mean temperature difference (LMTD) for counter-flow, parallel-flow, and cross-flow heat exchangers. Computes the LMTD correction factor F, overall heat transfer coefficient U, heat transfer area A, NTU-effectiveness, and heat duty Q = U·A·LMTD.

Signal-to-Noise Ratio Calculator | SNR, PSNR & Noise Figure in dB

Calculate signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), noise figure (NF), noise factor, and dynamic range for audio, electronics, and imaging applications. Converts between linear power ratios and decibels, and computes thermal noise floor.

Pool Calculator | Volume, Chlorine, pH & Chemical Dosing

Calculate swimming pool water volume in gallons for any pool shape — rectangular, oval, round, kidney, and L-shaped. Uses volume to calculate correct chlorine, shock, alkalinity adjustment, stabilizer, and pH balancing chemical doses with turnover rate and pump run time.