Units & measures

Convert between units with to, in or as, name what you are measuring to convert across dimensions, and write rates naturally.

Unit conversion#

1cm to m

2h to s

5km to m

30 degC to degF

100 lb in kg

A length, mass or volume written in two units is their sum, in the smaller unit, and min and sec are the minute and the second wherever a unit goes.

6 ft 2 in

1 m 80 cm

1 h to min

CSS units are supported too, so you can check a layout:

1 cm in px

2 em in px

Areas and volumes can be written in words: 20 sq cm, 30 square inches, 5 m squared, 3 ft cubed, 11 sqm, 11 cbm or with ² and ³ (10 m²). They read as cm^2, inches^2, m^2, and so on.

Measurement system#

Cooking volume units follow the measurement system in Settings → Measurement system — Metric (default), US customary or Imperial. It sets cup to 250, 236.6 or 284.1 ml respectively, along with tsp, tbsp, fl oz, pint, quart and gallon.

Cooking & measures#

Convert between dimensions by naming what you are measuring. The subject is free-form and optional: a known ingredient uses its density, a fuel its energy density, media their bitrate, and anything else a default (water). Write it before to/in.

300g butter in cups

2 cups flour in grams

1 cup sugar in grams

300g in cups

300g feathers in cups

1 l petrol in kWh

2 hours 4k video in GB

Rates#

A rate is one unit per another. mathjs does the arithmetic; these phrases make rates easy to write. per, a, an, at and for are all understood.

90 km / 3 day

30 hours at 10 km/hour

100 km at 10 km/hour

24 km a day for a year

time to upload 3 GB at 10 MB/s

The verb is optional.

time to 100 km at 50 km/h

5 km in 25 min

Two units of the same kind named with per, a or an stay a rate: 8 hours a day is 8 hours/day, 8 hours per day for a week is 56 hours, and work * 22 days after work = 8 hours a day is 176 hours. A plain / is a ratio (3 hours / day is 0.125).

Custom units#

Define your own unit with unit <name> = <amount>. It then behaves like a built-in one: the plural works, it converts to the units it was defined from, and it merges with them. Change the definition and every use follows. The plural of the last word is generated in the usual English ways (box/boxes, bus/buses, leaf/leaves, potato/potatoes) and ão becomes ões or ães; for any other plural, use the singular.

unit widget = 3.5 kg
2 widgets

unit widget = 3.5 kg
2 widgets in kg

A name may contain several words or accents, and a unit can be built from another.

unit monthly rent = 1500
2 monthly rents

unit widget = 3.5 kg
unit box = 12 widgets
2 boxes in kg

Definitions are scoped to the sheet that contains them, so removing the line removes the unit. unit and total are reserved words.

The unit rule#

Units only combine in shapes that mean something. kg L, BRL hour, h^2 and m^0.5 are reported as errors rather than as strange combined units. Money only forms ratios (USD/hour, USD/km), so use a rate when you want to convert a currency across time or distance.

Unit reference#

See the mathjs units reference for the full list. Time and temperature units can also appear in dates and timespans.