Enter BTU or calories into the calculator to convert to the other value, with support for IT/thermochemical BTU and small-calorie or dietary Calorie (kcal) units.
Common Mistakes Quick tips
- Entering values in both fields; fill exactly one: either BTU or calories.
- 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 (1054.35026444 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).
- All Unit Converters
- Cal to BTU Conversion Calculator
- BTU to Kilocalories Conversion Calculator
- KJ to Calories Calculator
- Cal to kWh Conversion Calculator
- kCal to Wh Conversion Calculator
Btu to Calories Formula
The following formulas convert BTU to calories and back using IT BTU and thermochemical calories as a common reference.
\quad
\mathrm{cal} = \mathrm{BTU}\times\frac{1055.05585262}{4.184}\quad\quad
\mathrm{BTU} = \mathrm{cal}\times\frac{4.184}{1055.05585262}- BTU (IT) = 1055.05585262 J; BTU (thermochemical) = 1054.35026444 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) | Calories (kcal) |
|---|---|
| 1 | 0.252 |
| 2 | 0.504 |
| 3 | 0.756 |
| 4 | 1.009 |
| 5 | 1.261 |
| 10 | 2.522 |
| 15 | 3.782 |
| 20 | 5.043 |
| 25 | 6.304 |
| 30 | 7.565 |
| 40 | 10.087 |
| 50 | 12.608 |
| 75 | 18.912 |
| 100 | 25.216 |
| 250 | 63.041 |
| 500 | 126.082 |
| 750 | 189.123 |
| 1,000 | 252.164 |
| 2,000 | 504.329 |
| * 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
