Conversion calculators

Unit conversion calculators for length, weight, temperature, speed, area, volume, and more. Accurate conversions using exact NIST-standard factors.

25 calculators

• Acres to Hectares Converter

  Convert between acres and hectares — bidirectional, exact, no rounding tricks. 1 acre = 0.40468564224 ha; 1 ha = 2.4710538147 acres.

• Area Converter

  Convert any area — metric or imperial. Square metres, square feet, acres, hectares, square miles, and the small units (cm², in², mm²) for design and engineering work.

• Bandwidth & Download Time Calculator

  Estimate how long it takes to transfer a file at a given connection speed. Handles bits vs bytes and decimal (MB) vs binary (MiB) units correctly.

• Bar to PSI Converter

  Convert between bar and pounds per square inch (psi) — bidirectional, exact, no rounding tricks. 1 bar = 14.5037737730 psi; 1 psi = 0.0689475729 bar.

• Binary Calculator

  Perform binary arithmetic and bitwise operations — add, subtract, multiply, divide, AND, OR, XOR — with results shown in binary, decimal, and hex.

• Celsius to Fahrenheit Calculator

  Convert between Celsius and Fahrenheit — bidirectional, exact, no rounding. Water freezes at 0 °C = 32 °F and boils at 100 °C = 212 °F.

• Cm to Inches Calculator

  Convert between centimetres and inches — bidirectional, exact, no rounding tricks. 1 in = 2.54 cm exactly; 1 cm ≈ 0.3937007874 in.

• Cooking Conversion Calculator

  Convert any cooking volume — cups, tablespoons, teaspoons, fluid ounces, millilitres, pints — between US customary, UK imperial and metric (250 mL) cups, with a kitchen-equivalents breakdown.

• Cups to Gallons Converter

  Convert between cups and gallons — US, imperial, and metric. Exact NIST and UK statutory factors, bidirectional, no rounding tricks.

• Distance & Length Converter

  Convert between any distance or length unit instantly — metric, imperial, or both at once.

• Force Converter

  Convert any force — SI, metric, US customary or CGS. Newtons, kilonewtons, pound-force, ounce-force, kilogram-force, dynes, poundals, tonne-force.

• Frequency Converter

  Convert any frequency — radio, audio, mechanical or angular. Hz, mHz, μHz, kHz, MHz, GHz, THz, rpm and rad/s.

• Fuel Consumption Converter

  Convert any fuel-economy reading: US mpg, Imperial mpg, litres per 100 km, or kilometres per litre. See all four at once, exact to NIST factors.

• Horsepower Converter

  Convert between mechanical horsepower (hp), metric horsepower (PS / ch / CV), electrical hp, boiler hp, watts, kilowatts, BTU per hour and foot-pounds per second.

• IP Subnet Calculator (CIDR)

  Enter an IPv4 address and a CIDR prefix (0–32). The calculator returns the network address, broadcast address, usable host range, subnet and wildcard masks, total addresses, host count, address class, and the IP and mask in binary.

• Pace Converter (min/km ↔ min/mile)

  Convert a running pace between minutes per kilometre and minutes per mile, with equivalent speed and projected race finish times.

• Pressure Converter

  Convert any pressure — SI, metric, US customary or vacuum/weather units. Pascals, bar, psi, atmospheres, mmHg, torr, inHg, ksi.

• Roman Numeral Converter

  Convert any whole number from 1 to 3999 into a Roman numeral, or any Roman numeral back into a decimal. Strict canonical form (MCMXCIV, not MDCCCCLXXXXIIII).

• Shoe Size Converter

  Convert any adult shoe size between US, UK, EU and Japanese (Mondopoint, cm) sizing. Pick your style (men’s/unisex or women’s), choose the region you know, and the calculator shows the equivalents in every other region plus an estimated foot length.

• Speed Converter

  Convert between any two units of speed — miles per hour, kilometres per hour, metres per second, knots, feet per second and more.

• Temperature Converter

  Convert any temperature — Celsius, Fahrenheit, Kelvin, Rankine, or Réaumur. Exact under the SI definitions; absolute zero is bounded.

• Time Converter

  Convert between any two units of time — milliseconds to millennia, with documented conventions for "month" and "year" so the answer is unambiguous.

• Unit Converter

  Convert between any two units in the same dimension — metric, imperial, US customary, and SI — with conversion factors that match NIST SP 811 and the 1959 International Yard and Pound Agreement.

• Volume & Capacity Converter

  Convert any volume — metric, US customary or UK imperial. Litres, gallons, fluid ounces, cups, cubic metres, even tablespoons and teaspoons.

• Weight & Mass Converter

  Convert between any weight or mass unit instantly — metric, imperial, US customary, or compound formats like stones and pounds.