Convert therms to watt-hours

1 thm=29,307.11Wh

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

You have

Equals

29,307.11

Conversion formula

Forward

watt-hours = therms × 29,307.11

Reverse

therms = watt-hours × 3.4121e-5

Example: 10 thm × 29,307.11 = 293,071.07 Wh.

About both units

From

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 →

Watt-Hour

The watt-hour equals 3600 joules — 1 W delivered for 1 hour. Used for phone, laptop and small-battery capacities. A typical smartphone battery is 10–20 Wh; a laptop is 50–100 Wh.

Real-world: iPhone battery: 12 Wh. MacBook Pro: 70 Wh. Power bank: 20 Wh–100 Wh. Airplane carry-on limit: usually 100 Wh.

Read full watt-hour reference →

Therm to Watt-Hour conversion table

Common therms to watt-hours values for quick reference.

Therm (thm)	Watt-Hour (Wh)
1 thm	29,307.11 Wh
10 thm	293,071.07 Wh
100 thm	2,930,710.7 Wh
500 thm	14,653,553.51 Wh
1,000 thm	29,307,107.03 Wh
5,000 thm	146,535,535.14 Wh
10,000 thm	293,071,070.28 Wh
50,000 thm	1,465,355,351.39 Wh
100,000 thm	2,930,710,702.78 Wh
500,000 thm	14,653,553,513.89 Wh

Tips & common mistakes

Quick 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.

Avoid these

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.

Frequently asked questions

How many watt-hours in a therm?

One therm equals 29,307.11 watt-hours.

How do I convert therms to watt-hours?

Multiply the therm value by 29,307.11 to get the equivalent in watt-hours.

What is 100 therms in watt-hours?

100 therms equals 2,930,710.7 watt-hours.

Is a therm bigger than a watt-hour?

Yes. 1 therm equals 29,307.11 watt-hours, so one therm is larger.

How to convert therms to watt-hours without a calculator?

Multiply by 29,307.11 for a quick estimate; use a calculator for precise results.

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