Engineering Calculators
Professional engineering calculators for electrical, mechanical, civil, and other engineering disciplines.
27 free tools available - no signup required
Professional-grade engineering calculators for students, technicians, and practicing engineers. Our tools cover electrical circuits (Ohm's law, wire gauge, LED resistors), mechanical systems, civil engineering (beam loads, concrete volume), HVAC sizing, solar panel output, and construction estimates. Each calculator uses standard engineering formulas and material properties.
Aerospace Engineering Calculator
Free aerospace engineering calculator for lift and drag force computation. Enter airspeed, wing area, and aerodynamic coefficients to calculate lift, drag, L/D ratio, and dynamic pressure for aircraft design and flight analysis.
Battery Life Calculator
Free battery life calculator to estimate runtime from battery capacity (mAh) and device current draw (mA). Calculate how long your battery will last, or determine the capacity needed for a target runtime.
Beam Load Calculator
Free beam load calculator for deflection, bending moment, shear force, and support reactions. Analyze simply supported and cantilever beams with point loads and distributed loads to verify structural adequacy.
Chemical Engineering Calculator
Free chemical engineering calculator for dilution and concentration problems. Use the C1V1 = C2V2 equation to find stock solution volume, solvent to add, and dilution factor for lab and industrial applications.
Civil Engineering Calculator
Free civil engineering calculator for beam deflection, bending moment, and shear force analysis. Enter load, span, moment of inertia, and elastic modulus to get instant structural results for simply supported beams.
Computer Engineering Calculator
Free computer engineering calculator for instant decimal, binary, octal, and hexadecimal number base conversion. Enter any non-negative integer up to 32 bits and see all four representations with bit-width and byte size.
Concrete Calculator
Free concrete calculator to estimate cubic yards and bags needed for slabs, patios, footings, and driveways. Enter length, width, and depth to get volume with a 10% waste factor, plus 60 lb and 80 lb bag counts.
Construction Calculator
Free construction calculator for drywall, flooring, and paint material estimates. Enter room dimensions to instantly calculate sheets, boxes, and gallons needed with a built-in 10% waste factor for accurate project planning.
Electric Current Converter
Free electric current converter for amperes, milliamperes, microamperes, kiloamperes, nanoamperes, and abamperes. Instantly convert between current units for circuit design, sensor specifications, and electrical safety analysis.
Electric Resistance Converter
Free electric resistance converter for ohms, kilohms, megohms, gigohms, milliohms, and microhms. Convert between resistance units for circuit design, component selection, insulation testing, and wire resistance calculations.
Electrical Calculator
Free electrical calculator using Ohm's Law to solve for voltage, current, resistance, and power. Enter any two values and get instant results for DC circuit design, electronics projects, and electrical engineering.
Electrical Wiring Calculator
Free electrical wiring calculator for wire gauge selection and voltage drop analysis. Enter amperage, voltage, and distance to find the correct AWG wire size per NEC code with real-time voltage drop percentage.
Electronics Calculator
Free electronics calculator for series and parallel resistor combinations. Enter two resistor values to instantly see total resistance for both configurations, plus the R1:R2 ratio for voltage divider design.
Flooring Calculator
Free flooring calculator to estimate material quantity, waste factor, and total cost. Enter room dimensions and material price to calculate square footage, boxes needed, and budget for hardwood, tile, laminate, or vinyl flooring.
HVAC Calculator
Free HVAC calculator for BTU sizing, tonnage estimation, and cooling/heating load calculation. Enter room dimensions, insulation level, and climate zone to determine the right AC or furnace size for your space.
LED Resistor Calculator
Free LED resistor calculator to find the correct current-limiting resistor for any LED circuit. Enter supply voltage, LED forward voltage, and desired current to get the resistor value and power rating needed.
Magnetic Flux Converter
Free magnetic flux converter for Weber, milliweber, microweber, Maxwell, and volt-second. Convert between SI and CGS magnetic flux units for transformer design, physics coursework, and electromagnetic calculations.
Mechanical Calculator
Free mechanical calculator for gear ratio, output speed, and torque multiplication. Enter driving and driven gear teeth counts to instantly calculate speed reduction, torque increase, and mechanical advantage for gearbox design.
Paint Calculator
Free paint calculator to estimate gallons needed for walls and ceilings. Enter room dimensions, coats, and coverage rate to get accurate material quantities and cost estimates for your painting project.
Physics Calculator
Free physics calculator for kinematics equations with constant acceleration. Enter initial velocity, acceleration, and time to compute final velocity, distance traveled, average velocity, and kinetic energy per kilogram.
Plumbing Calculator
Free plumbing calculator for pipe flow rate and water velocity. Select pipe diameter and set velocity to calculate GPM flow rate, liters per minute, and cross-sectional area for residential and commercial plumbing system design.
Radiation Converter
Free radiation unit converter for Sievert, millisievert, microsievert, rem, millirem, Gray, and rad. Convert between radiation dose units for health physics, radiology, occupational safety, and nuclear industry compliance.
Solar Panel Calculator
Free solar panel calculator to estimate system size, energy production, cost savings, and ROI. Enter your electricity usage and location to determine how many panels you need, annual kWh output, and payback period.
Sound Converter
Free sound level converter for decibels (dB), bels (B), and nepers (Np). Convert between logarithmic sound and signal units for audio engineering, acoustics, telecommunications, and noise measurement applications.
Voltage Converter
Free voltage unit converter for volts, millivolts, microvolts, kilovolts, and megavolts. Instantly convert between voltage scales for electronics, power systems, and sensor applications with precise decimal scaling.
Wallpaper Calculator
Free wallpaper calculator to estimate how many rolls you need for a room. Enter wall dimensions, roll size, and pattern repeat to calculate rolls required, usable coverage, and estimated cost with waste factor.
Wire Gauge Calculator
Free wire gauge calculator for AWG sizing, ampacity lookup, and voltage drop analysis. Enter your circuit amperage and distance to find the correct copper or aluminum wire gauge per NEC standards.
Engineering Guides
How Much Paint Do I Need? Room-by-Room Calculator Guide
One gallon of interior paint covers 350-400 square feet in one coat. A standard 12x12 bedroom needs 1.5-2 gallons for walls and ceiling with two coats -- but the actual number depends on color, surface, and whether you prime first.
7 min readHow to Calculate Concrete for Any Project: Slabs, Footings, and Posts
Concrete is sold by the cubic yard. A standard 10x10 ft patio at 4 inches thick takes 1.23 cubic yards -- but ordering the right amount requires knowing how slabs, footings, and post holes each get calculated differently.
8 min readAre Solar Panels Worth It in 2026? ROI by State
A 10 kW solar system costs $28,000 before the federal tax credit and $19,600 after. In California, that system pays back in 6.2 years and generates $89,000 in savings over 25 years. In Louisiana, payback stretches to 14 years. Location is everything.
9 min readReviewed & Methodology
Every calculator is built using industry-standard formulas, validated against authoritative sources, and reviewed by a credentialed financial professional. All calculations run privately in your browser - no data is stored or shared.