Unit Converter

How to use

1. Choose Length, Weight, Volume, Area, Speed, Data size, or Temperature under "Category"
2. Enter a number in "Value" and pick the units under "From" and "To"
3. The result appears automatically. Use the ⇄ button to swap the From and To units
4. Under the result, "In other units" lists the same value in every unit of the category except From. The "Copy" buttons next to the result and on each row copy that value

The result is a single line with the value you entered and the converted value, such as 1 m = 3.28084 ft. Switching the category resets the units to that category's defaults (m → ft for length, kg → lb for weight, L → gal (US) for volume, m² → ft² for area, km/h → mph for speed, GB → GiB for data size, °C → °F for temperature). The value you entered is kept.

The other-units list and copying

The list shows every unit except From, in the same order as "Supported units" below, including the unit chosen under To when it differs from From. For example, entering 1 m in Length gives:

• mm: 1,000

• cm: 100

• km: 0.001

• in: 39.370079

• ft: 3.28084

• yd: 1.093613

• mi: 0.000621

• Every value in the list is converted directly from the value you entered, and follows the same digit and display rules as the result.

• A unit the value is too large to be represented in shows "—" and has no copy button (mm for 1e305 km, for example).

• The list is not shown when "Value" is empty, or when a temperature below absolute zero is entered.

• "Copy" copies the number alone, without the unit. It is rounded to the same digits as the display, has no digit grouping, and always uses "." as the decimal point whatever your browser's language (1,000,000 mm copies as 1000000, 6.213712E-7 mi as 6.213712E-7), so it pastes straight into a spreadsheet or code.

Supported units

• Length: mm (millimeter), cm (centimeter), m (meter), km (kilometer), in (inch), ft (foot), yd (yard), mi (mile)
• Weight: mg (milligram), g (gram), kg (kilogram), t (tonne), oz (ounce), lb (pound)
• Volume: mL (milliliter), L (liter), m³ (cubic meter), gal (US) (US gallon), fl oz (US) (US fluid ounce)
• Area: mm² (square millimeter), cm² (square centimeter), m² (square meter), km² (square kilometer), a (are), ha (hectare), in² (square inch), ft² (square foot), yd² (square yard), ac (acre), mi² (square mile), tsubo
• Speed: m/s (meter per second), km/h (kilometer per hour), mph (mile per hour), kn (knot), ft/s (foot per second)
• Data size: bit, B (byte), kB, MB, GB, TB (steps of 1000), KiB, MiB, GiB, TiB (steps of 1024)
• Temperature: °C (degree Celsius), °F (degree Fahrenheit), K (kelvin)

Conversion works only between units of the same category. You cannot convert across categories, such as from length to weight.

Conversion factors

The value is first converted to the base unit of the category (m for length, kg for weight, L for volume, m² for area, m/s for speed, B for data size) and then to the target unit. These are the factors used for the non-metric units.

• 1 in = 0.0254 m (2.54 cm)
• 1 ft = 0.3048 m
• 1 yd = 0.9144 m
• 1 mi = 1609.344 m
• 1 oz = 0.028349523125 kg
• 1 lb = 0.45359237 kg
• 1 gal (US) = 3.785411784 L
• 1 fl oz (US) = 0.0295735295625 L
• 1 m³ = 1000 L, 1 t = 1000 kg

These are the factors used for area, speed, and data size.

• 1 a = 100 m², 1 ha = 10,000 m², 1 km² = 1,000,000 m²
• 1 in² = 0.00064516 m² (6.4516 cm²)
• 1 ft² = 0.09290304 m²
• 1 yd² = 0.83612736 m²
• 1 ac = 4046.8564224 m²
• 1 mi² = 2,589,988.110336 m²
• 1 tsubo = 400 ÷ 121 m² (about 3.305785 m²; 121 tsubo is exactly 400 m²)
• 1 km/h = 1000 ÷ 3600 m/s (3.6 km/h is exactly 1 m/s)
• 1 mph = 0.44704 m/s (1.609344 km/h)
• 1 kn = 1852 ÷ 3600 m/s (1.852 km/h, one nautical mile per hour)
• 1 ft/s = 0.3048 m/s
• 1 B = 8 bit
• 1 kB = 1000 B, 1 MB = 1000 kB, 1 GB = 1000 MB, 1 TB = 1000 GB
• 1 KiB = 1024 B, 1 MiB = 1024 KiB, 1 GiB = 1024 MiB, 1 TiB = 1024 GiB

Temperature formulas

Each temperature scale puts its zero in a different place, so multiplying by a factor is not enough. The value is first converted to °C and then to the target unit.

• °F → °C: (°F − 32) × 5 ÷ 9
• °C → °F: °C × 9 ÷ 5 + 32
• K → °C: K − 273.15
• °C → K: °C + 273.15

°F and K are converted through °C with the same formulas (0 °F = 255.372222 K).

Some reference points:

• Absolute zero: -273.15 °C = -459.67 °F = 0 K
• Where °C and °F read the same: -40 °C = -40 °F = 233.15 K
• Water freezes: 0 °C = 32 °F = 273.15 K
• Water boils: 100 °C = 212 °F = 373.15 K

Examples

Some conversions that come up when reading heights, distances, package weights, or drink sizes written in another system.

• 180 cm → 5.905512 ft
• 10 in → 25.4 cm
• 42.195 km → 26.218757 mi
• 100 yd → 91.44 m
• 150 lb → 68.038856 kg
• 60 kg → 132.277357 lb
• 1 oz → 28.349523 g
• 12 fl oz (US) → 354.882355 mL
• 50 L → 13.208603 gal (US)

Floor and land area, driving and wind speeds, and storage capacity:

• 100 m² → 30.25 tsubo
• 30 tsubo → 99.173554 m²
• 1000 ft² → 92.90304 m²
• 1 ha → 2.471054 ac
• 1 mi² → 2.589988 km²
• 100 km/h → 62.137119 mph
• 60 mph → 96.56064 km/h
• 36 km/h → 10 m/s
• 30 kn → 55.56 km/h
• 500 GB → 465.661287 GiB
• 16 GiB → 17.179869 GB
• 100 MB → 95.367432 MiB
• 1 MB → 8,000,000 bit

Weather, body temperature, and oven settings:

• 25 °C → 77 °F
• 100 °F → 37.777778 °C
• 36.5 °C → 97.7 °F
• 98.6 °F → 37 °C
• 350 °F → 176.666667 °C
• 180 °C → 356 °F
• 25 °C → 298.15 K
• 300 K → 80.33 °F

Digits and display

• Ordinary values are rounded to at most 6 decimal places. Trailing zeros are not shown (1 lb = 16 oz).
• A nonzero result whose absolute value is below 0.000001 is shown in scientific notation with up to 7 significant digits, so it is not rounded to zero (1 mm = 6.213712E-7 mi).
• Large values get digit grouping (1 km = 1,000,000 mm). The grouping and decimal symbols follow your browser's language setting.
• "—" is shown when "Value" is empty or when the result is too large to be represented as a number. The result's copy button is not shown then.
• Negative values and 0 are accepted (-5 cm = -1.968504 in, 0 ft = 0 m).
• Temperature is the one category with a lower limit. A value below absolute zero (-273.15 °C, -459.67 °F, 0 K) gives "—" with a note underneath naming the limit. Absolute zero itself converts (-273.15 °C = 0 K).
• Adding and subtracting the zero points leaves a very small calculation error. When a temperature result is within that error of a round value (up to 9 decimal places), it is shown as that value (-459.67 °F = 0 K, 98.6 °F = 37 °C). Any fraction larger than the error is kept.

Things to keep in mind

• The gallon and fluid ounce are the US units. The UK gallon and fluid ounce are different sizes and are not covered by this app.
• The tsubo is the Japanese unit used for floor and land area, taken here as 1 tsubo = 400 ÷ 121 m². The tatami mat (jō) is left out because the size of one mat varies by region and building. Japanese property listings count one mat as at least 1.62 m², so multiplying the mat count by 1.62 gives a minimum area.
• kB, MB, GB, and TB grow in steps of 1000; KiB, MiB, GiB, and TiB grow in steps of 1024. They are different units. Some software, including Windows, counts in steps of 1024 and still labels the value "GB". Choose GiB here when you are working with such a value.
• bit and B (byte) are different units. A connection speed in "Mbps" counts bits, so a 100 Mbps line carries 12.5 MB each second (100 MB is 800,000,000 bit). The app does not cover per-second units themselves.
• The knot (kn) is used for ships, aircraft, and wind, and is one nautical mile (1852 m) per hour.
• The acre (ac) and square mile (mi²) are based on the international foot. Values based on the US survey foot differ slightly from the sixth significant digit on.
• A combined entry such as "5 feet 11 inches" is not possible. Convert it to a single value in feet or in inches first.
• Temperature conversion re-reads a temperature, not a difference. To turn a change such as "5 °C warmer" into °F, multiply by 9 ÷ 5 without adding 32 (a 5 °C difference is a 9 °F difference). Entering 5 °C here gives 41 °F, which is the temperature 5 °C on the other scale, not the size of the change.
• K (kelvin) is written without "°". A step of 1 K is the same size as 1 °C; only the zero is shifted by 273.15.
• The result is already rounded when displayed. Converting a displayed value again to another unit can be off by that rounding, so convert directly from the original value or use the "In other units" list.

FAQ

What does "E" mean in a small result?

It is scientific notation, showing the power of 10. For example, 1E-9 t from converting 1 mg to t means 0.000000001 t. Only results with an absolute value below 0.000001 use this form. Converting 1000 mg to t lands exactly on that boundary, so it is shown as 0.000001 t.

How many centimeters is one inch?

2.54 cm. In the Length category, set From to in and To to cm to see 1 in = 2.54 cm.

How many kilograms is one pound?

0.45359237 kg. The app rounds to 6 decimal places, so it shows 1 lb = 0.453592 kg.

How many square meters is one tsubo?

About 3.305785 m². In the Area category, set From to tsubo and To to m² to see 1 tsubo = 3.305785 m². To go the other way, multiply square meters by 0.3025 (100 m² = 30.25 tsubo).

Why does a 500 GB drive show up as 465 GB?

Product capacity is written in GB that grow in steps of 1000, while some operating systems count in steps of 1024 and still label the value "GB". In the Data size category, converting 500 GB to GiB gives 465.661287 GiB, which matches that display. No capacity is missing.

How many MB is 1 GB?

1 GB = 1,000 MB. In the 1024-based units, 1 GiB = 1,024 MiB. Mixing the two gives a fraction, such as 1 GiB = 1,073.741824 MB.

How do I turn km/h into m/s?

Divide by 3.6 (36 km/h = 10 m/s). In the Speed category, set From to km/h and To to m/s.

Does it support temperature conversion?

Yes. Choose "Temperature" under Category to convert between °C (Celsius), °F (Fahrenheit), and K (kelvin). Temperature cannot be converted by multiplying by a factor alone, so it uses the formulas under "Temperature formulas" above.

Is there a quick way to estimate Fahrenheit in Celsius?

Subtract 30 and halve it (86 °F gives 28; the exact value is 30 °C). For everyday weather the estimate is within a few degrees. Use the app for the exact value.

Why does -300 °C give "—"?

No temperature is lower than absolute zero (-273.15 °C). The limits are -459.67 for °F and 0 for K.

What does "t" mean?

The metric ton (1,000 kg).

What happens if From and To are the same unit?

The result is the same value you entered (the display is still rounded to 6 decimal places).

Why does a copied value have no digit grouping?

So that a spreadsheet or program reads it as a number when you paste it. Group separators, or a "," used as the decimal point, can make the value be taken as text. The unit is left off too, so add it where you paste if you need it.

Is my data saved?

No. The conversion runs entirely in the browser, and the value you enter is never sent to a server. The page returns to its initial state when you reload it.