Units

📏Unit Expression Rules

Calcumber understands quantities consisting of a dimensionless magnitude and a unit expression that can be written in a natural way. However some rules are needed to prevent misinterpretation of unit symbols as variables.

✅ OK	❌ Not OK	📌 Rule
1 m	1m	Use a space between magnitude and unit.
1 W/(m^2*K)	1 W / (m^2*K)	Don’t use spaces within a unit.
3m * 2 m	3 m*2 m	Use a space between unit and succeeding operator.
1 W/m^2*K		In units, multiplication * has higher precedence than division /. Brackets are optional.
60 m3	50 s-1	For positive integer exponents, the operator ^ can be omitted.
1 W/m2K	1 W/m^2K	After a short-form exponentiated unit, multiplication * can be omitted.

📏Predefined Units in Calcumber

Calcumber comes with a rich set of predefined units — including SI base units, derived units, common non-SI units.

🧱 SI Base Units

Any unit that is not defined in terms of other units is treated as a base unit in Calcumber. This includes the standard SI base units:

s – second (time)

m – metre (length)

kg – kilogram (mass)

A – ampere (electric current)

K – kelvin (temperature)

mol – mole (amount of substance)

cd – candela (luminous intensity)

🔧 Derived SI Units

These are defined in terms of the base units and commonly used in science and engineering:

Unit	Name	Definition
rad	radian	1 (angle)
sr	steradian	1 (solid angle)
Hz	hertz	1/s
N	newton	kg*m/s^2
Pa	pascal	N/m^2
J	joule	N*m
W	watt	J/s
C	coulomb	A*s
V	volt	J/C
F	farad	C/V
Ohm	ohm	V/A
S	siemens	1/Ohm
Wb	weber	V*s
T	tesla	Wb/m^2
H	henry	Wb/A
lm	lumen	cd*sr
lx	lux	lm/m^2
Bq	becquerel	1/s
Gy	gray	J/kg
Sv	sievert	J/kg
kat	katal	mol/s

⏱ Non-SI Units Accepted with SI

These are widely used and accepted in scientific and technical fields:

Unit	Name	Definition
min	minute	60 s
h	hour	60 min
d	day	24 h
au	astronomical unit	149,597,870,700 m
deg	degree	π/180 rad
arcmin	arcminute	1/60 deg
arcsec	arcsecond	1/60 arcmin
ha	hectare	10,000 m²
L	litre	0.001 m³
t	tonne (metric ton)	1000 kg
Da	dalton	1.66053906892e-27 kg
eV	electronvolt	1.602176634e-19 J

📏 Additional Metric Units

Unit	Description	Definition
are	area unit	100 m²
dioptre	lens power	1/m
bar	pressure unit	100000 Pa

🧪 Other Predefined Units

Unit	Description	Definition
year	Calendar year (approximate)	365.25 d
month	Month (approximate)	1/12 year
week	Week	7 d
Wh	Watt hour	W*h

🇬🇧 Imperial and US Customary Units

Unit	Description	Definition
in	inch	0.0254 m
ft	foot	12 in
yd	yard	3 ft
mi	mile	5280 ft
mil	thou (thousandth of inch)	0.001 in
ac	acre	43560 ft²
gal	US gallon	3.785411784 L
qt	US quart	gal / 4
pt	US pint	qt / 2
cup	US cup (approximate)	0.24 L
floz	US fluid ounce	gal / 128
tbsp	tablespoon	floz / 2
tsp	teaspoon	tbsp / 3
lb	pound	0.45359237 kg
oz	ounce	lb / 16
st	stone	14 lb
ton_us	US ton	2000 lb
ton_uk	UK long ton	2240 lb
lbf	pound-force	4.4482216152605 N
psi	pounds per square inch	lbf / in²
atm	standard atmosphere	101325 Pa
°F	Fahrenheit (differential)	5/9 K
mph	miles per hour	mi / h
fps	feet per second	ft / s
kt	knot	1852 m / h
BTU	British thermal unit	1055.05585262 J
cal	calorie	4.184 J
Cal	calorie on food labels	1 kcal

☕Implicit Units / User Defined Units

Calcumber treats any undefined unit as a base unit — even if it’s something like coffee, EUR, or bean. These units don’t need to be pre-defined, and Calcumber will still allow meaningful calculations and unit cancellations.

7 coffe/day * 0.5 EUR/coffee ➔ 3.5 EUR/day

use year ➔ 1278.375 EUR/year

Even though coffee and EUR are not built-in units, Calcumber:

Cancels out coffee correctly

Recognizes day and converts it to year

So yes — you can calculate your yearly caffeine budget, even in undefined units. Coffee may come at a price — but at least it’s healthier than 1278 lbpy (liters beer per year 😉).

🪄Commands for Unit Manipulation

ubase

Converts to base units:

ubase 5 N → 5 kg*m^2/s^2

Without arguments, ubase coverts the last result to base units:

10 m/s^2 * 0.5 kg → 5 N ubase → 5 kg*m/s^2

use

Tells Calcumber what unit to use.

Syntax:

use unit, [expression]

Writes expression using a power of the specified unit times a base unit remainder:

expression → magnitude unit^n*remainder.

Examples:

use N, 30 J → 30 m*N

use kWh, 9 MJ → 2.5 kWh

use A, 9 MJ → 9000000 kg*m^2/s^2 (Joule does not contain Ampère in its definition)

use s, 50 Hz → 50 1/s

use m, 200 L → 0.2 m^3

If expression is omitted, use applies to the last result:

50 L/min * 34 min → 1700 L

use m → 1.7 m^3