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Enter Btu or kilocalories into the calculator to convert to the other value.
Assumptions Assumptions
- Conversions are energy-to-energy only; no power or rate conversions.
- Joules (J) are used as the base unit: values use standard constants shown below.
- Supported definitions: Btu (IT) = 1055.05585262 J; Btu (thermochemical) = 1054.35026444 J; kilocalorie (IT) = 4186.8 J; kilocalorie (thermochemical) = 4184 J.
- “Calorie” on food labels (Cal) equals 1 kilocalorie (kcal).
- Results are rounded to 6 decimal places for display.
When to Use This Calculator
- Converting heating/cooling energy between Btu and food/thermal kilocalories.
- Comparing appliance energy ratings or fuel heat content across unit systems.
- Standardizing engineering or nutrition notes without manual lookup tables.
Input Definitions
- Btu — select International Table (IT) or thermochemical definition.
- Kilocalories — select IT or thermochemical definition; 1 kcal = 1 Cal (food calorie).
- Conversions — IT: kcal = Btu × 0.252164401; Btu = kcal × 3.968320719. General: kcal = Btu × (J_per_Btu ÷ J_per_kcal).
Btu to Kilocalories Formula
The following formulas convert between Btu and kilocalories using the International Table (IT) definitions; other definitions are noted below.
\mathrm{kcal}_{\mathrm{IT}} = 0.252164401\,\mathrm{Btu}_{\mathrm{IT}}\mathrm{Btu}_{\mathrm{IT}} = 3.968320719\,\mathrm{kcal}_{\mathrm{IT}}- Btu (International Table) = 1055.05585262 J
- Btu (thermochemical) = 1054.35026444 J
- Kilocalorie (IT) = 4186.8 J
- Kilocalorie (thermochemical) = 4184 J
How do you convert Btu to kilocalories? For IT units, multiply Btu by 0.252164401; for thermochemical, multiply Btu by (1054.35026444 ÷ 4184) ≈ 0.252164.
How do you convert kilocalories to Btu? For IT units, multiply kilocalories by 3.968320719; for thermochemical, multiply kilocalories by (4184 ÷ 1054.35026444) ≈ 3.968321.
Btu to Kilocalories Conversion Table
| Btu (IT) | Kilocalories (IT) |
|---|---|
| 0.5 | 0.126082 |
| 1 | 0.252164 |
| 2 | 0.504329 |
| 3 | 0.756493 |
| 5 | 1.260822 |
| 10 | 2.521644 |
| 15 | 3.782466 |
| 20 | 5.043288 |
| 25 | 6.304110 |
| 30 | 7.564932 |
| 40 | 10.086576 |
| 50 | 12.108220 |
| 75 | 18.162330 |
| 100 | 25.216440 |
| 150 | 37.824660 |
| 200 | 50.432880 |
| 250 | 63.041100 |
| 500 | 126.082201 |
| 1000 | 252.164401 |
| * IT definitions: 1 Btu = 0.252164 kcal; 1 kcal = 3.968321 Btu (rounded). | |
Example Problem
Convert 2,500 Btu (IT) to kilocalories (IT).
Use the IT formula: kcal = Btu × 0.252164401.
kcal = 2,500 × 0.252164401 = 630.411003 ≈ 630.411 kcal
