Quick Answer: Kilowatt-hours to Therms
One kilowatt-hour is approximately 0.03412 therms (1 kWh ≈ 0.03412 thm).
Conversely, 1 thm ≈ 29.31 kWh.
Formula: therms (US) = kWh ÷ 29.307107
Worked examples
- 29.3 kWh ≈ 0.9998 thm
- 100 kWh ≈ 3.412 thm
- 293 kWh ≈ 9.998 thm
Method and limitations
Divide kilowatt-hours by 29.307107 to express energy in US therms — useful when comparing a gas boiler against a heat pump on a common unit. The UK therm (105,506,000 J = 29.307222 kWh) differs by four parts per million. Calculations use full-precision constants; answers in this box are rounded for readability (≈ marks a rounded value) and the calculator shows up to 9 significant figures. The therm here is the US therm, defined as 100,000 International Table BTU.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
Divide kilowatt-hours by 29.307107 to express energy in US therms — useful when comparing a gas boiler against a heat pump on a common unit. The UK therm (105,506,000 J = 29.307222 kWh) differs by four parts per million.
Complete Guide to Kilowatt-hours to Therms Conversion
What is a kilowatt-hour?
A kilowatt-hour (kWh) is one kilowatt sustained for one hour and the universal unit of electricity billing, battery capacity and solar production.
What is a therm?
A therm is 100,000 BTU of energy. US gas utilities bill in therms; older British bills also used therms (with a slightly different UK definition) before UK bills moved to kWh.
How the Conversion Works
Because one BTU is 1,055.06 J and one kWh is 3,600,000 J, 100,000 Btu(IT) works out to 29.307107 kWh. Gas meters measure volume; the utility multiplies by a calorific value to arrive at therms, then bills that figure.
Why This Conversion Matters
Comparing gas heating with electric heating or a heat pump needs both in the same unit first, then each adjusted: gas energy × boiler efficiency gives delivered heat, and delivered heat ÷ SCOP gives a heat pump's electricity use.
Scientific Context
The energy content (calorific value) of natural gas per cubic metre or cubic foot varies with its composition. Where gas is metered by volume, utilities apply a stated calorific value to convert volume into therms or kWh, which is why the same volume can produce slightly different energy readings month to month.
Step-by-Step Conversion Guide
Follow these steps to convert kilowatt-hours to therms manually:
Start with your value in kilowatt-hours
Example: You want to convert 293 kWh
Apply the conversion formula
Use the formula: therms (US) = kWh ÷ 29.307107
Calculate the result
293 kWh = 9.9976 thm
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Divide kilowatt-hours by 29.307107 to express energy in US therms — useful when comparing a gas boiler against a heat pump on a common unit. The UK therm (105,506,000 J = 29.307222 kWh) differs by four parts per million.
Common Conversions
| Kilowatt-hours (kWh) | Therms (thm) | Therms → Kilowatt-hours |
|---|---|---|
| 29.3 kWh | 0.999757 | 29.3 thm = 858.698 kWh |
| 100 kWh | 3.41214 | 100 thm = 2,930.71 kWh |
| 293 kWh | 9.99757 | 293 thm = 8,586.98 kWh |
| 500 kWh | 17.0607 | 500 thm = 14,653.6 kWh |
| 1000 kWh | 34.1214 | 1000 thm = 29,307.1 kWh |
| 2930 kWh | 99.9757 | 2930 thm = 85,869.8 kWh |
| 5000 kWh | 170.607 | 5000 thm = 146,536 kWh |
| 10000 kWh | 341.214 | 10000 thm = 293,071 kWh |
When You'll Need This Conversion
Gas versus heat pump decisions
Convert your gas bill into kWh to compare it directly against electric heating costs.
Mixed-fuel energy totals
Express gas and electricity use in one unit (kWh) to see a building's total energy use.
Annual heat demand estimate
A year of therms × 29.307107 × boiler efficiency estimates the annual heat (kWh) a replacement must supply. Equipment size (kW) needs a heat-loss calculation, not annual energy.
Energy literacy
Understand what a utility statement actually charges for.
Pro Tips for Accurate Conversions
Always adjust for efficiency
Multiply gas kWh by your boiler's seasonal efficiency, from its datasheet or energy label, to get delivered heat before comparing with a heat pump.
Use a whole heating season
Single-month comparisons are distorted by weather. Twelve months of therms gives a usable baseline.
Check the calorific value on your bill
It shifts by a few percent between suppliers and seasons, which changes your therm total.
Common Mistakes to Avoid
Comparing gas and electricity unit prices directly
A therm contains 29.3 times the energy of a kWh, so gas always appears cheaper per unit.
Convert to a common unit, then divide by appliance efficiency or COP.
Assuming 100% boiler efficiency
No boiler turns all of the gas energy into useful heat; part is lost in the flue gases.
Use the appliance efficiency rating printed on the unit.
Ignoring standing charges
Fixed daily gas charges continue even after switching most heating to electricity.
Include standing charges in any switching calculation.
History & Background
Gas is billed by energy content rather than volume because the energy in a given volume of gas varies with its composition. The therm — 100,000 BTU — is the energy billing unit used in the US and, historically, in Britain.
Key Milestones
The International Table BTU (1,055.05585262 J) is adopted; the US therm is 100,000 of these.
Global Usage Today
US gas bills commonly use therms. Many European bills, including current UK bills, state gas in kWh; some Australian bills use megajoules.
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.