How many BTU is 1 calorie?

1 thermochemical calorie (cal) equals approximately 0.003966 BTU. Equivalently, 1 BTU equals about 252.164 thermochemical calories. The exact factor is 1 cal = 4.184 J and 1 BTU = 1055.06 J, giving 4.184 / 1055.06 ≈ 0.003966 BTU per calorie.

What is the difference between a calorie and a kilocalorie (kcal)?

1 kilocalorie (kcal) equals 1,000 calories (cal). Nutrition labels use "Calories" (capital C) to mean kilocalories — so a 200-Calorie food contains 200 kcal or 200,000 cal. This tool handles both: enter cal in the top field or kcal in the dedicated kcal field.

Which calorie definition does this converter use?

This converter uses the thermochemical calorie (cal_th), defined as exactly 4.184 joules. It is the most common definition in chemistry and engineering. The International Table calorie (4.1868 J) differs by less than 0.07% — negligible for most practical conversions.

How do I convert food Calories (kcal) to BTU?

Multiply the kcal value by 3.96567. For example, a 500 kcal meal contains 500 × 3.96567 ≈ 1982.8 BTU. The kcal input field on this page does this automatically.

Why would I need to convert calories to BTU?

The BTU is the standard energy unit in US HVAC, heating equipment, and appliance ratings, while calories appear in chemistry, nutrition, and European engineering. Converting between them is common when comparing food energy to fuel energy, sizing heating systems, or working with mixed-unit datasheets.

How many BTU are in 1 kcal?

1 kilocalorie (kcal) = 3.96567 BTU. Since food Calories are kcal, a 2,000 Calorie daily diet equals about 7,931 BTU — roughly equivalent to burning one-fifth of a cubic foot of natural gas.

Calories to BTU Converter

Name: Calories to BTU Converter
Availability: InStock
Author: Nham Vu

Enter a calorie value and get the BTU equivalent instantly, with reverse BTU-to-calorie conversion and a quick-reference table.

Converter

Calories (cal)

Result in BTU

Kilocalories (kcal / food Calories)

Kilocalories (kcal)

Result in BTU

Reverse: BTU to calories

BTU

Result in calories (cal)

Reference Table

Calories (cal) BTU

1 cal 0.003966

10 cal 0.039657

100 cal 0.39657

252 cal 0.99936

500 cal 1.9828

1,000 cal 3.9657

1 kcal 3.9657

2,000 cal 7.9313

5,000 cal 19.828

10,000 cal 39.657

100,000 cal 396.57

1,000 kcal 3,965.7

Formula: BTU = cal × 0.0039657 • cal = BTU × 252.164
Based on thermochemical calorie (1 cal = 4.184 J exactly).

Summary

Enter a calorie value and get the BTU equivalent instantly, with reverse BTU-to-calorie conversion and a quick-reference table.

How it works

Enter a calorie (cal) value in the top input field.
The BTU result appears instantly — no button press needed.
Use the kilocalorie (kcal) field to convert food Calories (the kind on nutrition labels).
Use the reverse field to convert BTU back to calories.
Click "Copy" next to any result to copy it to your clipboard.
Check the reference table for common cal-to-BTU values at a glance.

Use cases

Compare food energy values between calorie-based nutrition labels and BTU-based fuel ratings.
Estimate heat output of a burner or stove in BTU from a known calorie rating.
Cross-check HVAC load calculations when source data is in calories.
Convert chemistry experiment heat values from calories to BTU for US engineering reports.
Translate dietary energy in kilocalories (kcal) to BTU for building energy modeling.
Verify boiler or water heater efficiency specs when units differ between manufacturers.
Convert calorimeter readings from cal to BTU for thermodynamic problem sets.
Compare propane or natural gas energy content listed in BTU to calorie equivalents.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu