Convert BTU to calories or calories to BTU from a single entered value using IT and thermochemical units, including cal, kcal, and dietary Calories.

Choose the unit definitions and enter the energy in BTU.

IT = International Table; th = thermochemical. Changing units converts the entered quantity.

A dietary Calorie is 1 thermochemical kcal, or 1,000 small calories.

Common Mistakes Quick tips
  • Choose the conversion direction, then enter the known energy and select the unit definitions.
  • Confusing small calories (cal) with dietary Calories (Cal or kcal). 1 Cal = 1000 cal.
  • Ignoring the slight difference between IT and thermochemical definitions for BTU and calorie.
  • Using energy conversions to compare temperatures directly—BTU and calories are energy, not temperature.
When to Use This Calculator
  • Converting HVAC/heating values (BTU) to food energy for intuition (kcal/Calories).
  • Standardizing energy units between engineering specs and nutrition references.
  • Switching among IT/thermochemical definitions for BTU and calories for precise work.
Input Definitions
  • BTU — select IT (1055.05585262 J) or thermochemical (approximately 1054.350264489 J).
  • Calories — choose small-calorie IT/thermochemical or dietary Calorie (kcal) options.
  • Conversions — via joules: valuetarget = valuesource × (J per source unit) ÷ (J per target unit).

Btu to Calories Formula

The following formulas convert BTU to calories and back using IT BTU and thermochemical calories as a common reference.

cal = BTU × (1055.05585262) / (4.184) BTU = cal × (4.184) / (1055.05585262)
  • BTU (IT) = 1055.05585262 J; BTU (thermochemical) = approximately 1054.350264489 J.
  • cal (thermochemical) = 4.184 J; cal (IT) = 4.1868 J; 1 Calorie (kcal, dietary) = 4184 J.

How do you convert BTU to calories? Using IT BTU and thermochemical calories, multiply BTU by 1055.05585262 ÷ 4.184 ≈ 252.164401 to get calories; for dietary Calories (kcal), multiply BTU by ≈ 0.252164401.

How do you convert calories to BTU? Multiply calories by 4.184 ÷ 1055.05585262 ≈ 0.00396567 to get BTU; for dietary Calories (kcal), multiply by ≈ 3.96567.

Btu to Calories Conversion Table

BTU (IT) to Calories (kcal, dietary)
BTU (IT) Calories (kcal)
10.252
20.504
30.756
41.009
51.261
102.522
153.782
205.043
256.304
307.565
4010.087
5012.608
7518.912
10025.216
25063.041
500126.082
750189.123
1,000252.164
2,000504.329
* Using IT BTU and dietary Calories (kcal): 1 BTU ≈ 0.252164 Cal; 1 Cal ≈ 3.96567 BTU.

Example Problem

Convert 1,000 BTU (IT) to dietary Calories (kcal).

Use the factor for BTU (IT) to kcal: Cal = BTU × 0.252164401.

Cal = 1,000 × 0.252164401 ≈ 252.164 kcal