Skip to content
    Search ⌘K
    Engineering / ZorvLabs Universal Unit Converter

    Unit Converter — Length, Weight, Temperature & More

    Free unit converter for length, mass, temperature, volume, speed, pressure, energy and data. Exact definitions, instant results, no signup.

    ToolCalculatorExecutionIn browserCategoryEngineering

    Unit Converter

    Convert any unit, instantly

    Length, mass, temperature, volume, area, speed, pressure, energy and data — converted through exact published definitions (SI units, international foot and pound, ISO BTU). Everything runs locally in your browser.

    100

    1 m = 100 cm

    m to everything in Length

    Millimeter1,000 mm
    Centimeter100 cm
    Meter1 m
    Kilometer0.001 km
    Inch39.370079 in
    Foot3.28084 ft
    Yard1.093613 yd
    Mile0.000621 mi
    Nautical mile0.00054 nmi

    Conversions use exact published definitions where they exist (1 in = 0.0254 m, 1 lb = 0.45359237 kg, 1 atm = 101325 Pa, 1 BTUISO = 1055.05585262 J) and round for display only. Last reviewed 2026-10-06. Results are informational — see our disclaimer.

    engineering methodology

    A clear path from inputs to results.

    Convert between metric and US units in one place: length, mass, temperature, volume, area, speed, pressure, energy and digital data. The converter uses the exact published definition of every unit — the international inch is exactly 2.54 centimeters, the pound is exactly 0.45359237 kilograms — so results are as precise as the definitions allow, not approximations.

    Step-by-step methodWorked exampleAssumptions explained

    How to use

    1. Pick a category from the tabs at the top: Length, Mass, Temperature, Volume, Area, Speed, Pressure, Energy or Data.
    2. Type the value you want to convert in the Value box.
    3. Choose the unit you are converting from in the left dropdown.
    4. Choose the target unit on the right — the result updates as you type, and the swap button reverses the direction instantly.
    5. Scroll to the table below to see the same value expressed in every unit of the category at once.

    The formula

    y=x⋅ffrom+ofrom−otoftoy = \frac{x \cdot f_{\text{from}} + o_{\text{from}} - o_{\text{to}}}{f_{\text{to}}}

    Reference: SI Brochure (BIPM) for metric definitions; NIST Handbook 44 and international yard-and-pound agreement for US customary definitions (1 in = 25.4 mm, 1 lb = 0.45359237 kg); ISO 80000 for BTU and thermochemical calorie.

    Worked example

    A 6-foot board in centimeters

    Inputs
    • 6 feet, converting to centimeters.
    Calculation path
    1. 1

      The international foot is defined as exactly 0.3048 meters, so 6 ft = 6 × 0.3048 = 1.8288 m. One meter is 100 centimeters, giving 1.8288 × 100 = 182.88 cm. The engine carries the factors at full double precision and only rounds for display, which is why the table can show 6 ft as 72 in, 1.8288 m and 182.88 cm consistently.

    Result

    6 ft = 182.88 cm (exactly, because the foot and centimeter are both exact definitions).

    Interpreting the result

    Every row of the conversion table is the same physical quantity expressed in a different unit — the underlying value never changes. Where a definition is exact (length, mass, data prefixes) the conversion has no measurement error at all; temperature and the conventional units like mmHg depend on the stated definition (e.g. thermochemical vs International Table calorie), which is why the page names the definition it uses.

    Assumptions & limitations

    • US liquid units are used for volume (1 US gallon = 3.785411784 L); imperial gallons are about 20% larger and are not included.
    • The calorie row is the thermochemical calorie (exactly 4.184 J); food "Calories" are kilocalories, listed separately.
    • Data units include both SI prefixes (1 kB = 1000 B) and binary prefixes (1 KiB = 1024 B) — storage vendors and operating systems use different ones, which is why a "1 TB" drive shows as 931 GiB.
    • Temperature conversions use the standard scale definitions (Celsius, Fahrenheit, Kelvin) with no adjustment for wind chill, humidity or the properties of real substances.

    Frequently asked questions

    Why do some conversions come out with long decimal tails?

    The converter shows up to 6 significant decimals, but factors like 1 mi = 1609.344 m are exact, so a value such as 1 mph in m/s is 0.44704 exactly while others (like psi to mmHg) are ratios of exact definitions that do not terminate. Rounding appears only in the display; the math itself uses full double precision.

    Why does my "1 terabyte" drive show 931 GiB?

    Drive makers use SI prefixes (1 TB = 1,000,000,000,000 bytes), while operating systems often report in binary prefixes (1 TiB = 1,099,511,627,776 bytes). The converter lists both families side by side: 1 TB equals 1000 GB in SI and about 909.5 GiB in binary units.

    How precise are the conversions?

    For length and mass the factors are definitions, not measurements, so the only error is your own input. For conventional units the page names the standard used (ISO BTU = 1055.05585262 J, thermochemical calorie = 4.184 J, conventional mmHg = 133.322387415 Pa); other references can differ in the last decimal place, which matters only for high-precision work.

    Is a US gallon the same as a UK gallon?

    No. A US liquid gallon is exactly 3.785411784 liters, while the imperial (UK) gallon is about 4.546 liters — roughly 20% larger. This converter uses US liquid units and labels them, so fuel and recipe conversions to metric are consistent with US packaging.

    What temperature scale should I pick for science work?

    Kelvin — it is the SI base unit and has no negative values, which keeps ratio-based physics (gas laws, thermodynamics) correct. Celsius and Fahrenheit are relative scales; the converter routes everything through Kelvin internally to keep the offsets exact, and −40 °F = −40 °C is the one point where the two scales read the same.

    Methodology last reviewed 2026-10-06. Results are informational and not financial or engineering advice — see our disclaimer.