Unit Conversion Factor Labels

Dimensional-analysis cheatsheet: convert through a base unit, cancel labels, and handle temperature offsets.

Name	Formula	Note
To base unit	`value_base = value_in × factor_in→base` Hop into a shared base before converting to the target.	Hop into a shared base before converting to the target.
From base unit	`value_out = value_base × factor_base→out` Second hop from base into the desired unit.	Second hop from base into the desired unit.
Factor-label cancel	`3 km × (1000 m / 1 km) = 3000 m` Write factors so unwanted units cancel like algebra.	Write factors so unwanted units cancel like algebra.
Length (SI hub)	`1 in = 0.0254 m · 1 ft = 0.3048 m · 1 mi = 1609.344 m` Common length factors via the meter.	Common length factors via the meter.
Mass (SI hub)	`1 lb = 0.45359237 kg · 1 oz = lb / 16` Common mass factors via the kilogram.	Common mass factors via the kilogram.
Celsius ↔ Fahrenheit	`°F = °C × 9/5 + 32` Affine map — scale and offset; not a pure ratio.	Affine map — scale and offset; not a pure ratio.
Celsius ↔ Kelvin	`K = °C + 273.15` Same degree size; only the zero point shifts.	Same degree size; only the zero point shifts.

Open a calculator and put these formulas to work.