Convert calories to therms

1 cal=3.9657e-8thm

Use the converter below to change any calories value into therms instantly — with formula, conversion table, and real-world examples.

You have

Equals

3.9657e-8

Conversion formula

Forward

therms = calories × 3.9657e-8

Reverse

calories = therms × 25,216,440.08

Example: 10 cal × 3.9657e-8 = 3.9657e-7 thm.

About both units

From

Calorie

cal

The gram calorie (small calorie) equals 4.184 joules — the energy to raise 1 g of water by 1 °C. It is a scientific unit, distinct from the nutrition "Calorie" (kcal). Largely replaced by joules in modern science.

Real-world: Raising 1 g of water 1 °C: 1 cal. A 100 kcal snack = 100,000 small calories.

Read full calorie reference →

Therm

thm

The therm equals 100,000 BTU or 105.5 megajoules. Used in US and UK natural-gas billing. A typical UK home uses 200–500 therms per year for heating.

Real-world: UK home heating: 200–500 therms/year. 1 therm = about $1.50 US (2024) or £1.00 UK.

Read full therm reference →

Calorie to Therm conversion table

Common calories to therms values for quick reference.

Calorie (cal)	Therm (thm)
1 cal	3.9657e-8 thm
10 cal	3.9657e-7 thm
100 cal	3.9657e-6 thm
500 cal	1.9828e-5 thm
1,000 cal	3.9657e-5 thm
5,000 cal	0.0001983 thm
10,000 cal	0.0003966 thm
50,000 cal	0.001983 thm
100,000 cal	0.003966 thm
500,000 cal	0.01983 thm

Tips & common mistakes

Quick tips

1 cal = 4.184 J. 1 kcal = 4184 J.
Scientific "calorie" and nutrition "Calorie" differ by 1000×.
Prefer joules in modern scientific writing.

Avoid these

Assuming "calories" on food labels means gram calories — they are kcal.
Mixing gram calories and kilocalories in calculations.
Confusing calorie (energy) with calorimeter (apparatus).

Frequently asked questions

How many therms in a calorie?

One calorie equals 3.9657e-8 therms.

How do I convert calories to therms?

Multiply the calorie value by 3.9657e-8 to get the equivalent in therms.

What is 100 calories in therms?

100 calories equals 3.9657e-6 therms.

Is a calorie bigger than a therm?

No. 1 calorie equals 3.9657e-8 therms, so one calorie is smaller.

How to convert calories to therms without a calculator?

Multiply by 0 for a quick estimate; use a calculator for precise results.

Related energy conversions

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