Convert kWh and US therms, then compare the same energy amount in BTU, megajoules, and optional bill costs.
Table of contents
How to use our kWh to Therms Converter
- Choose the Convert direction that matches the energy unit you already have.
- Enter either Energy amount (kWh) or Energy amount (therms); the hidden amount is not used.
- Open Advanced options only if you want cost results, then enter Electricity price ($ per kWh), Gas price ($ per therm), or choose a Number display.
- Select Calculate and read Converted energy first, then use Same energy in BTU and Same energy in megajoules as check values.
- Sanity-check the result: 100 kWh should be about 3.412 therms, and 1 therm should be about 29.307 kWh.
Definitions
kWh: A kilowatt-hour is an energy amount. Electric bills often use kWh for electricity used over time.
Therm: A US therm is an energy amount used on many natural gas bills. This converter uses 1 therm = 100,000 Btu.
BTU: British thermal unit. It is a heat-energy unit, not a speed or rate by itself.
Megajoule: A metric energy unit. One megajoule is 1,000,000 joules.
kW: Kilowatt. This is a power rate, meaning how fast energy is used. It is not the same as kWh.
BTU per hour: A heat rate. It tells how fast heat is delivered, while BTU alone is an energy amount.
Break-even price: The gas or electricity price where the same raw energy amount costs the same before appliance efficiency is considered.
Common mistakes and quick fixes
Mistake: Entering kW in Energy amount (kWh) .
Fix: Use an energy amount in kWh; kW is a rate, not a stored or used amount of energy.
Mistake: Leaving the visible Energy amount (therms) blank after choosing therms to kWh.
Fix: Enter a therm amount greater than 0 before calculating Converted energy .
Mistake: Using cents in Electricity price ($ per kWh) , such as 16 instead of 0.16.
Fix: Enter dollars per kWh, so 16 cents becomes 0.16.
Mistake: Putting a monthly gas bill total in Gas price ($ per therm) .
Fix: Use the delivered price per therm from your bill if you want Cost at your gas price to be meaningful.
Mistake: Treating Lower cost at entered prices as the final heating winner.
Fix: Remember it compares raw energy only; real heating cost also depends on equipment efficiency and losses.
Mistake: Thinking Same energy in BTU means BTU per hour.
Fix: BTU here is an energy amount; BTU per hour is a rate.
Limitations & Key Assumptions / Boundary Conditions
- This converter compares energy amounts, not useful heat delivered into a room or water tank.
- Appliance efficiency is not included. A furnace, heat pump, stove, or water heater can change real operating cost.
- Bill prices can include delivery charges, fixed fees, taxes, tiers, and seasonal rates. Use all-in variable rates when comparing energy costs.
- The therm here is the US therm based on 100,000 Btu. Other billing systems or countries may use different gas units.
- Optional cost cards appear only when the matching price field is entered and valid.
- Very tiny or very large entries are rounded for display, but the conversion uses the stated factors before formatting.
Methodology
Conversion factors
The converter treats kWh and therms as energy units. It uses 1 kWh = 3.6 MJ and 1 therm = 100,000 Btu, then derives the kWh-to-therm factor from those energy conversions [1].
therms = kwh * 0.03412141633
kwh = therms * 29.30710702
btu = kwh * 3412.141633
mj = kwh * 3.6
Cost comparison
If a price is entered, the same energy amount is priced in that unit. The electricity cost uses the kWh equivalent. The gas cost uses the therm equivalent.
electricity_cost = kwh_equiv * electricity_price
gas_cost = therms_equiv * gas_price
Break-even prices show the price where raw energy costs would tie.
break_even_gas_price = electricity_price * 29.30710702
break_even_electricity_price = gas_price * 0.03412141633
Mini example
For 100 kWh, the therm conversion is 100 * 0.03412141633 = 3.412141633 therms. The same energy is 100 * 3412.141633 = 341,214.1633 BTU and 100 * 3.6 = 360 MJ. If electricity is $0.16 per kWh, the raw electricity cost is 100 * 0.16 = $16.00. The matching gas break-even price is 0.16 * 29.30710702 = $4.68913712 per therm.
Calculation choices
Energy amounts must be greater than 0. Optional prices may be blank, but entered prices must be 0 or higher. Commas and spaces are removed before parsing numbers, so 1,250 is read as 1250.