Unit Conversion Calculators

Length, weight, volume, temperature, speed and area converters — exact factors, with no rounding until the final digit.

Exact conversion factors — not rounded approximations — for length, weight, volume, temperature, speed and data. Each converter shows the factor it applies and the reverse direction, so a millimetre that matters stays precise instead of drifting through chained approximations.

Methodology: Exact or published conversion factors, applied with the standard significant-figure rules.

Length Converter

Convert between length units

Weight Converter

Convert between weight units

Volume Converter

Convert between volume units

Area Converter

Convert between area units

Speed Converter

Convert between speed units

Data Storage Converter

Convert between data units

Angle Converter

Convert between angle units

Energy Converter

Convert between energy units

Pressure Converter

Convert between pressure units

Frequency Converter

Convert between frequency units

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin

Time Converter

Convert time units (hours, minutes, seconds)

Force Converter

Convert force units (N, kN, lbf)

Fuel Efficiency Converter

Convert fuel economy (MPG, L/100km)

Cooking Measurement Converter

Convert cooking measurements

Clothing Size Converter

Convert international clothing sizes

Shoe Size Converter

Convert international shoe sizes

Currency Converter (Fixed Rate)

Convert currencies at fixed rates

Torque Converter

Convert torque units (Nm, lb-ft)

Power Converter

Convert power units (W, kW, HP)

Electrical Unit Converter

Convert electrical units info

Radiation Converter

Convert radiation measurement units

Density Converter

Convert density units

Viscosity Converter

Convert viscosity units

Bit Rate Converter

Convert data rates between bps, Kbps, Mbps, Gbps

Luminance Converter

Convert between lux, foot-candles, nits

Molarity Converter

Convert concentration between M, mM, µM, nM

Flow Rate Converter

Convert between L/s, L/min, m³/h, GPM

Paper Size Converter

A/B-series paper sizes and dimensions

Fraction ↔ Percent ↔ Decimal

Convert between fraction, percent, and decimal

Roman Numeral Converter

Convert between Arabic numbers and Roman numerals

PPM / Concentration Converter

Convert between ppm, ppb, and percent

Thermal Conductivity Converter

Convert W/(m·K) to BTU/(ft·h·°F) etc

Radiation Dose Converter

Convert between Gray, rad, Sievert, rem

Wire Gauge (AWG) Converter

Convert AWG to mm and mm²

Acceleration Converter

m/s², g-force, ft/s², km/h per second

Frequently asked questions

Why does a "1 TB" drive show less space than expected?

Drive capacity is usually quoted in decimal units (1 TB = 1,000 GB) while operating systems report binary units (1 TiB = 1,024 GiB). The difference is about 9%, and it explains almost every "missing space" complaint. Convert using the same base the label uses before comparing.

Temperature is a special case — why?

Because Celsius and Fahrenheit have different zero points as well as different step sizes, temperature is a shift-and-scale conversion rather than a simple ratio. Kelvin, by contrast, shares Celsius's step size, so only the offset is needed.

Are the conversion factors exact?

Defined relationships — such as inch to millimetre, or pound to kilogram — are exact and used at full precision. Older or customary measures, especially cooking volumes, vary by country and are approximations, which is why weight is the more reliable way to scale a recipe.

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About CalcProMaster calculators

CalcProMaster is a free library of 1285 online calculators across 20 categories — finance, health, math, business, construction, engineering, conversion, education and more. Every calculator runs entirely in your browser: no sign-up, no paywall, and no data leaves your device.

What makes these calculators different is transparency. Each tool shows the exact formula it uses. It also shows a step-by-step breakdown of how your inputs become the result. That way you can check the math instead of trusting a black box. Every calculator page explains how to read the result. It also lists common mistakes, assumptions and limitations. An FAQ sits with every one, and the most-used tools add a worked example. Health and finance tools name the formula they follow. Calorie needs use Mifflin-St Jeor. Loans use standard amortization. Each page says plainly when an answer should be confirmed with a professional.

The guides library goes deeper on the calculations people search for most. It covers percentage and discount math, loan EMI and amortization, income-tax brackets, calorie and macro planning, and concrete volumes. Each guide gives the formula, worked examples and links to the matching calculator. The glossary defines the terminology in plain language. The public formula QA dashboard shows the verification status of every calculator's math.

Popular starting points: loan EMI calculator, BMI calculator, percentage calculator, random number generator, and concrete calculator. You can also browse a category above to find the tool you need.

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