Engineering & Electronics Calculators
Quick engineering calculations with the formula and units next to every result. They are estimates for design work and study — have a qualified engineer verify anything safety-critical.
All 31 engineering tools
Grouped by what they do.
Electrical & power
10 toolsPower, wiring and energy storage.
- Motor Torque, Power & Speed Calculator Torque ↔ power ↔ speed, slip and motor current — with every formula shown.
- Ohm's Law Calculator Any two of V, I, R and P give the other two — with the working shown.
- Battery Life & Backup Time Calculator Device runtime, inverter backup, cell packs and charge time — formulas shown.
- Watts to Amps Calculator (kW, kVA, HP) kW, kVA, amps and horsepower for DC, single-phase and three-phase loads.
- mAh to Wh Converter mAh ↔ Wh at the battery’s voltage, power-bank output and the airline Wh limits.
- Three-Phase Power Calculator Balanced or per-phase loads: kW, kVA, kvar, neutral current and unbalance.
Show all 10 Show fewer Electrical & power tools
- Solar Panel & Battery Size Calculator Panels, batteries and controller for your daily kWh — NASA sun data for 237 cities.
- Voltage Drop Calculator Drop in volts and percent, load voltage and cable losses — with the formula shown.
- Cable Size Calculator Smallest cable for voltage drop and short circuit — and which check governs.
- Wire Gauge Converter (AWG, SWG, mm²) AWG and SWG to mm, mm², kcmil and the nearest metric size — with printable charts.
Electronics & circuits
10 toolsComponents and circuits.
- Capacitor Code Calculator Read any capacitor marking, or find the codes for a value — in pF, nF and µF at once.
- PCB Trace Width Calculator Trace width, current, temperature rise, resistance and vias — every formula shown.
- Karnaugh Map Solver Minterms, a truth table or an expression in — minimal SOP and POS out, groups drawn.
- Series & Parallel Resistor Calculator Combine parts, solve whole networks and make odd values from two standard parts.
- Voltage Divider Calculator Divider output, the resistors for a target voltage, and bridges — with the load included.
- LED Resistor Calculator The right resistor for your LEDs, its wattage, the real current and the power wasted.
Show all 10 Show fewer Electronics & circuits tools
- RC, LC & Active Filter Calculator Cutoff from parts, or parts from a cutoff — with standard values and a Bode plot.
- Resistor Color Code Calculator Colours to ohms and ohms to colours — IEC 60062:2016, with the E-series check.
- 555 Timer Calculator Frequency and duty cycle from parts, or parts for your frequency — with E-series values.
- SMD Resistor Code Calculator Read chip-resistor markings or find the code for a value — every scheme, both ways.
Mechanical & machining
5 toolsMachine parts, fasteners and machining.
- Metal Weight Calculator Weight of any bar, plate, tube or section — per metre, per piece and for the whole order.
- Gear Ratio & Spur Gear Calculator Tooth counts in — ratio, speed, torque, direction and gear dimensions out.
- Bolt Torque & Preload Calculator Torque for a target preload — or preload from a torque — with every formula shown.
- Tap Drill Size & Thread Calculator The right drill for any tap, the thread it gives and the nearest stock drills.
- Speeds & Feeds Calculator RPM, feed rate, metal removal and power — metric or inch, with every formula shown.
Structures & materials
2 toolsHow structures and materials carry load.
Fluids & piping
3 toolsFlow in pipes and channels, and the equipment that drives it.
- Reynolds Number Calculator Laminar or turbulent? Re for a pipe, duct, channel or plate, with real fluid properties.
- Pipe Pressure Drop Calculator Friction, fittings, valves and lift — the head your pump has to deliver, with the working.
- Tank Volume Calculator Volume at any liquid level for tanks with real heads — plus mass, ullage and a dip chart.
HVAC & thermal
1 toolHeating, cooling and thermal design.
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- All 31 tools run in your browser: what you open or paste is not uploaded.
- All of them keep working without a connection once loaded.
- Results are estimates for planning and learning, not engineering advice. Check the method and assumptions on each tool’s page.
Other categories
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- 95 tools Text Count, clean, sort, compare.
- 92 tools Image Compress, resize, convert, crop.
- 55 tools PDF Merge, split, extract, convert.
- 35 tools Audio & Video Convert, trim, compress media.
- 56 tools Design Colours, gradients, CSS.
- 36 tools SEO Meta tags, sitemaps, schema.
- 27 tools Social Media Captions, previews, limits.
- 94 tools Finance Loans, savings, interest, tax.
- 78 tools Business Invoices, quotes, margins.
- 39 tools Legal Templates and legal maths.
- 48 tools Health BMI, calories, pregnancy.
- 51 tools Math Calculators and solvers.
- 45 tools Science Physics, chemistry, astronomy.
- 29 tools Construction Materials, area, home costs.
- 80 tools Education Grades, citations, study.
- 36 tools Network DNS, headers, IPs, subnets.
- 35 tools Security Passwords, encryption, keys.
- 33 tools Converters Every unit, exact factors.
- 75 tools Utility Convert, count down, randomise.