How many calories is 1 BTU?

1 BTU (thermochemical) equals approximately 251.996 thermochemical calories. This comes from the thermochemical BTU definition: 1 BTU_th = 1054.35 J, and the thermochemical calorie definition: 1 cal_th = 4.184 J, giving 1054.35 / 4.184 ≈ 251.996 cal.

How do I convert BTU to calories manually?

Multiply the BTU value by 251.996. For example, 5 BTU × 251.996 = 1259.98 cal. To convert in the other direction, divide calories by 251.996 (or multiply by 0.003968).

What is the difference between BTU and calorie?

BTU (British Thermal Unit) is the energy needed to raise 1 pound of water by 1°F. A thermochemical calorie (cal) is the energy needed to raise 1 gram of water by 1°C. Both measure heat energy but are used in different regions and fields — BTU in US HVAC and engineering; calories in chemistry, nutrition, and science.

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

Divide the calorie result by 1000, or multiply BTU directly by 0.251996. For example, 10 BTU × 0.251996 = 2.520 kcal. Since nutrition labels use food Calories (which equal kcal), 10 BTU equals about 2.520 food Calories.

Why would I need to convert BTU to calories?

BTU is the standard energy unit in US HVAC, heating equipment, and appliance ratings, while calories appear in chemistry, nutrition, and European engineering. Converting is common when comparing heating system output to food energy, working with international engineering documents, or solving thermodynamics problems with mixed units.

What is 1000 BTU in calories?

1000 BTU equals 251,996 calories (roughly 252 kcal). This is a useful reference: a window air conditioner rated at 5,000 BTU removes about 1,260,000 cal (1,260 kcal) of heat per hour from a room.

BTU to Calories Converter

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

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

Converter

BTU (British Thermal Units)

Result in calories (cal)

Result in kilocalories (kcal / food Cal)

Reverse: calories to BTU

Calories (cal)

Result in BTU

Reference Table

BTU Calories (cal)

0.001 BTU 0.252

0.01 BTU 2.520

0.1 BTU 25.20

1 BTU 251.996

5 BTU 1,259.98

10 BTU 2,519.96

100 BTU 25,199.6

1,000 BTU 251,996

5,000 BTU 1,259,980

1 kBTU 251,996

Formula: cal = BTU × 251.996 • BTU = cal ÷ 251.996
Based on thermochemical BTU (1 BTU = 1054.35 J) and thermochemical calorie (1 cal = 4.184 J).

Summary

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

How it works

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

Use cases

Convert HVAC heater or air conditioner ratings from BTU to calories for European datasheets.
Translate gas burner output in BTU to calories for chemistry or nutrition comparisons.
Convert food energy values from BTU (used on some US appliance labels) to calories.
Cross-check boiler efficiency specs when source data uses BTU and target report uses cal.
Convert calorimeter experiment results from BTU to cal for thermodynamics homework.
Compare fuel energy density listed in BTU/lb to calorie equivalents.
Convert propane or natural gas energy content from BTU to kcal for dietary comparisons.
Translate air conditioning capacity in BTU/hr to calorie equivalents for HVAC load tables.

Frequently Asked Questions

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