Convert Calories to Therms
Convert Calories (cal) to Therms (thm) instantly and accurately.
Conversion Formula
thm = cal × 3.965666831e-8
About Calories
A calorie (cal) - the thermochemical calorie - is exactly 4.184 J, defined as the heat to raise 1 g of water by 1°C. Standard since 1954. The calorie is the fundamental unit of heat measurement in thermochemistry: glucose combustion releases 669.9 kcal/mol; water vaporisation requires 539.7 cal/g. Bond dissociation energies in quantum chemistry are often quoted in kcal/mol. Note: the dietary Calorie (capital C) on food labels is 1 kcal = 4,184 J - a factor-of-1,000 difference that causes persistent confusion. 1 cal = 4.184 J = 1.163 × 10⁻³ Wh.
About Therms
A therm is the US natural gas billing unit equal to exactly 100,000 BTU = 105,505,585.262 J ≈ 105.5 MJ. One CCF of average US pipeline gas contains ~1.02 therms. The EIA publishes residential gas prices in $/therm; spot prices at Henry Hub are in $/MMBTU (1 MMBTU = 10 therms). US households average 500-700 therms/year for space heating, water heating, and cooking. A 15 kW domestic boiler running 2 hours delivers ~1 therm of useful heat. 1 therm = 100,000 BTU = 105.506 MJ = 29.307 kWh = 25,200 kcal.
Quick Reference Table
| Calories (cal) | Therms (thm) |
|---|---|
| 1 cal | 3.966 × 10-8 thm |
| 2 cal | 7.931 × 10-8 thm |
| 5 cal | 1.983 × 10-7 thm |
| 10 cal | 3.966 × 10-7 thm |
| 25 cal | 9.914 × 10-7 thm |
| 50 cal | 1.983 × 10-6 thm |
| 100 cal | 3.966 × 10-6 thm |