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What is a therm?

The US and UK gas-billing unit — 100,000 BTU

Definition

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.

Common uses

  • US residential gas bills
  • UK commercial gas billing
  • Industrial natural-gas contracts

🌍 Real-world scale

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

Convert from therms

9 conversions
Therm to Joule1 thm = 105,505,585.3 JTherm to Kilojoule1 thm = 105,505.59 kJTherm to Megajoule1 thm = 105.506 MJTherm to Kilowatt-Hour1 thm = 29.3071 kWhTherm to Watt-Hour1 thm = 29,307.11 WhTherm to Calorie1 thm = 25,216,440.08 calTherm to Kilocalorie1 thm = 25,216.44 kcalTherm to British Thermal Unit1 thm = 100,000 BTUTherm to Electronvolt1 thm = 6.5851e26 eV

Convert to therms

9 conversions
Joule to Therm1 J = 9.4782e-9 thmKilojoule to Therm1 kJ = 9.4782e-6 thmMegajoule to Therm1 MJ = 0.009478 thmKilowatt-Hour to Therm1 kWh = 0.03412 thmWatt-Hour to Therm1 Wh = 3.4121e-5 thmCalorie to Therm1 cal = 3.9657e-8 thmKilocalorie to Therm1 kcal = 3.9657e-5 thmBritish Thermal Unit to Therm1 BTU = 1.0000e-5 thmElectronvolt to Therm1 eV = 1.5186e-27 thm

Tips

  • 1 therm = 100,000 BTU = 105.5 MJ = 29.3 kWh.
  • UK bills often quote both therms and kWh.
  • In metric-dominant EU, gas is billed in kWh or m³.

Common mistakes

  • Comparing therms and kWh without conversion on a mixed-unit bill.
  • Assuming therms are used globally — only US and UK.
  • Using BTU when bill shows therms — factor of 100,000.

FAQ about the therm

What is a therm?
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.
Where is the therm used?
The therm is commonly used for: US residential gas bills; UK commercial gas billing; Industrial natural-gas contracts.
What is an example of a therm in real life?
UK home heating: 200–500 therms/year. 1 therm = about $1.50 US (2024) or £1.00 UK.
What category does the therm belong to?
The therm is a unit of energy, part of the 10-unit energy category on UnitConv.
How accurate are therm conversions?
All conversion factors follow NIST and BIPM international standards to 8 significant figures — the highest practical accuracy.
Explore all 10 energy units and their conversions.⚡ Energy hub →