cal Other
Measures: Energy — how much work can be done
Calorie (thermochemical)
The heat unit food labels made famous — with a twist.
EnergyHow it's defined
Defined as exactly 4.184 joules. The twist: food "Calories" (capital C) are kilocalories — 4,184 J each. A 2,000-Calorie diet is 8.4 megajoules; the capital letter hides a factor of a thousand.
1 cal = 4.184 J — exact1 food Calorie (kcal) = 4,184 J — exact
Convert — honestly
cal equals
4.184 J
Joule · factor exact — the base unit itself
0.00000116222222 kWh
Kilowatt-hour · factor exact — exact by definition
Conversions run through the joule using the stated factors — no rounding beyond display precision, and every factor says whether it's exact or measured.
Where you meet it
- Every nutrition label (as kcal)
- Nutrientii-to-be — its energy column
Other ways to measure energy
Source
This page is an authored summary of the authoritative definition — checkable one click away.
NIST Special Publication 811 — Guide for the Use of the SI