Tools for engineers
Calculators for engineering design, site work and study, grouped by discipline, together with the math and unit tools that go with them. Results are design estimates: have a qualified engineer check anything safety-critical.
Gathered from the Engineering, Converters, Math, Construction, Developer, Data, Design and Utility categories.
Electrical & electronics
20 toolsFor power, wiring and circuits.
- Capacitor Code Calculator Read any capacitor marking, or find the codes for a value — in pF, nF and µF at once.
- 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.
- PCB Trace Width Calculator Trace width, current, temperature rise, resistance and vias — every formula shown.
- Battery Life & Backup Time Calculator Device runtime, inverter backup, cell packs and charge time — formulas shown.
- Karnaugh Map Solver Minterms, a truth table or an expression in — minimal SOP and POS out, groups drawn.
Show all 20 Show fewer Electrical & electronics tools
- Series & Parallel Resistor Calculator Combine parts, solve whole networks and make odd values from two standard parts.
- 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.
- 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.
- 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.
- 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.
- Wire Gauge Converter (AWG, SWG, mm²) AWG and SWG to mm, mm², kcmil and the nearest metric size — with printable charts.
Mechanical, fluids & HVAC
11 toolsFor machines, structures, flow and heat.
- HVAC BTU & Tonnage Calculator Btu/h, tons and kW from airflow, water flow or room size — solve any way, see the working.
- Metal Weight Calculator Weight of any bar, plate, tube or section — per metre, per piece and for the whole order.
- Beam Deflection Calculator Reactions, diagrams and deflection for any mix of point, uniform, varying or moment loads.
- Gear Ratio & Spur Gear Calculator Tooth counts in — ratio, speed, torque, direction and gear dimensions out.
- Moment of Inertia & Section Properties Calculator Every section property of a standard or custom shape, with the composite-area working.
- Bolt Torque & Preload Calculator Torque for a target preload — or preload from a torque — with every formula shown.
Show all 11 Show fewer Mechanical, fluids & HVAC tools
- 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.
- 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.
- Tank Volume Calculator Volume at any liquid level for tanks with real heads — plus mass, ullage and a dip chart.
Civil & construction
10 toolsFor concrete, masonry and reinforcement.
- Concrete Calculator (Slab, Footing, Column, Tube & Steps) Add up every slab, footing, column and step — then get m³, yd³, bags and truckloads.
- Concrete Mix Calculator — Cement, Sand & Aggregate (IS 456) Cement bags, sand and aggregate for M5–M20 concrete, checked against IS 456.
- Brick Calculator — Bricks, Mortar, Cement & Sand Bricks, mortar, cement and sand for any wall — IS 1077, UK or US brick sizes.
- Plaster & Screed Calculator Cement and sand for walls, ceilings and floor screeds, with IS 1661 thickness guidance.
- Rebar (TMT Steel) Weight Calculator Steel weight from bar size, length and count — IS 1786, D²/162 and US bar sizes.
- Concrete Mix Design Calculator (IS 10262:2019) Every IS 10262 step for an M10–M60 trial mix, checked against IS 456 durability limits.
Show all 10 Show fewer Civil & construction tools
- Block Calculator — Concrete, CMU & AAC Blocks Blocks, mortar or adhesive and grout for any block wall — IS 2185 and US CMU sizes.
- Bar Bending Schedule (BBS) Calculator A complete BBS — shapes, cutting lengths, counts, laps and steel weight by diameter.
- Reinforcement Steel Quantity Estimator Quick rebar take-off for slabs and members, with the IS 456 limits checked.
- Structural Steel Weight Calculator (Plates, Pipes, Angles, Beams) IS 808 sections, plates, bars and tubes — kg per metre, per piece and for the whole list.
Math for engineering
20 toolsFor the maths behind the design.
- Basic Calculator A desk calculator that never drifts: exact decimals, % that works, and a paper tape.
- Matrix Calculator Matrices up to 10 × 10 in exact fractions — every step, from determinants to the SVD.
- Quadratic Equation Solver Any rearranged quadratic solved exactly three ways, with discriminant, vertex and graph.
- Standard Deviation Calculator σ and s with the full working — for lists, frequency tables and class intervals.
- Mean, Median, Mode & Average Calculator Every kind of average with the working — lists, frequency tables and class intervals.
- Scientific Calculator Type or tap: trig, logs, roots and constants, with exact answers when they exist.
Show all 20 Show fewer Math for engineering tools
- System of Equations Solver Linear systems in exact fractions — six methods, every step, and a graph for two unknowns.
- Factoring Calculator (Factor, Expand & Simplify) Complete factorisation over the integers with named steps, plus expand and simplify.
- Graphing Calculator Plot equations, curves and regions, then trace them, slide them and share them.
- Z-Score & Normal Distribution Calculator z-scores, normal probabilities and percentiles — with a shaded bell curve and a z-table.
- Probability Calculator Exact answers with the working — from coin tosses and dice to Bayes’ theorem.
- Sequence & Series Calculator (AP, GP & Pattern Finder) Arithmetic, geometric and harmonic progressions, pattern finder and exact Σ / Π.
- Derivative Calculator Every rule shown — product, quotient, chain — plus partials, implicit dy/dx and tangents.
- Permutation & Combination Calculator Exact counts with the formula and steps — and the actual arrangements for small cases.
- Scatter Plot Maker Scatter and bubble charts with trendlines, their equations and R².
- Descriptive Statistics Calculator Every summary statistic of your data, with a box plot, histogram and stem-and-leaf.
- Equation Solver Solve for x: exact answers where they exist, every root checked, both sides graphed.
- Integral Calculator Antiderivatives with steps, definite and improper integrals — every answer checked.
- Sample Size Calculator How many to ask or measure — for a survey, a mean or a comparison of two groups.
- Big Number Calculator Every digit exact: huge sums, products, powers, roots and factorials.
Units & conversions
30 toolsFor converting between units.
- Unit Converter Exact conversions for 14 kinds of units, with the formula and a full table.
- KG to LBS Converter Exact kg ↔ lb with pounds and ounces, stones and pounds and a printable 1–200 kg chart.
- Length Converter Exact length conversions with feet and inches, inch fractions and every unit at once.
- mL to Fluid Ounces Converter Exact mL ↔ fl oz in US and UK ounces, the 30 mL label rule and the 3.4 oz liquids limit.
- Time Unit Converter Exact durations in every unit, with a days-hours-minutes breakdown and ISO 8601.
- Celsius to Fahrenheit Converter Exact °C ↔ °F with the working shown, a mental shortcut and weather, oven and body tables.
Show all 30 Show fewer Units & conversions tools
- Data Storage Converter Exact bits and bytes in decimal and binary units — and why 1 TB shows as 931 GB.
- Land Area Converter — Bigha, Guntha, Cent, Marla, Acre Land units by state, from official records — or your own local bigha.
- Liters to Gallons Converter Exact L ↔ gal, US or imperial, with quarts and pints, tank tables and price per gallon.
- Weight Converter Exact weight conversions with lb + oz, st + lb and traditional Indian units.
- Data Rate Converter (Mbps to MB/s) Bits per second to bytes per second and back — 100 Mbps is 12.5 MB/s.
- Feet to Meters Converter Exact ft ↔ m with feet and inches, centimetres, printable tables and the US survey foot.
- Square Feet to Square Meters Converter Exact sq ft ↔ m², rooms in feet and inches, gaj, guntha and price per sq ft or per m².
- Temperature Converter Exact °C, °F and K conversions with the formula worked step by step.
- Acres to Hectares Converter Exact acre ↔ hectare with sq ft, m², guntha and cents, square-plot sides and farm tables.
- Area Converter Exact area conversions, a length × width helper and fixed Indian land units.
- KM to Miles Converter Exact km ↔ miles with nautical miles, race distances from 5K to marathon and road charts.
- Pressure Converter Exact pressure and stress units, with psig ↔ psia and barg ↔ bara.
- Roman Numeral Converter 1994 ⇄ MCMXCIV — with a strict notation check, dates and a full chart.
- CM to Inches Converter Exact cm ↔ inches, with tape-measure fractions, feet and inches and printable tables.
- Cups to Grams Converter Cups and spoons to grams and back for 100+ ingredients, each from a cited USDA record.
- Decimal to Fraction Converter Decimals, repeating decimals, fractions and percents — converted exactly, with the method.
- MM to Inches Converter (with Fractions) Exact mm ↔ inches with the nearest 1/8–1/64 inch and its error, thou and a fraction chart.
- Number to Words Converter 12,34,567 → twelve lakh thirty-four thousand … — and back, exactly.
- Volume Converter Exact volume conversions, US and UK measures, and an L × W × H box helper.
- Cups to mL Converter (Cooking Measures) Every cup and spoon — US, label, metric, Australian, UK and Japanese — in mL and back.
- Height Converter (cm to Feet and Inches) Body height in feet and inches, centimetres and metres — typed any way you like.
- Ounces to Grams Converter Exact oz ↔ g with lb and oz, the US 28 g label rule, troy ounces and kitchen tables.
- PX to REM Converter px ⇄ rem, em and every CSS length unit — or convert a whole stylesheet at once.
- Speed Converter Exact speed conversions, Mach numbers by altitude and the ×5/18 shortcut.
Programming helpers
4 toolsFor number formats and checksums in embedded and software work.
- Number Base Converter Binary, octal, decimal, hex and every base to 36 — exact, with the working shown.
- Programmer Calculator (Bitwise) Bitwise maths at a real bit width — with overflow, endianness and every base at once.
- IEEE 754 Floating-Point Converter See exactly how a number is stored in binary floating point — every bit, every digit.
- CRC Calculator (CRC-8/16/32/64) Every catalogued CRC, custom parameters, checksums and C code — for text, hex or files.
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Good to know
- All 95 tools run in your browser: what you open or paste is not uploaded.
- All of them keep working without a connection once loaded.
- Calculator results and templates are starting points for planning, not legal or engineering advice. Check the method and assumptions on each tool’s page.
- Free to use, with nothing to install and no account.
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