Convert watt-hours to therms

1 Wh=3.4121e-5thm

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

You have

Equals

3.4121e-5

Conversion formula

Forward

therms = watt-hours × 3.4121e-5

Reverse

watt-hours = therms × 29,307.11

Example: 10 Wh × 3.4121e-5 = 0.0003412 thm.

About both units

From

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

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 to Therm conversion table

Common watt-hours to therms values for quick reference.

Watt-Hour (Wh)	Therm (thm)
1 Wh	3.4121e-5 thm
10 Wh	0.0003412 thm
100 Wh	0.003412 thm
500 Wh	0.01706 thm
1,000 Wh	0.03412 thm
5,000 Wh	0.1706 thm
10,000 Wh	0.3412 thm
50,000 Wh	1.70607 thm
100,000 Wh	3.41214 thm
500,000 Wh	17.0607 thm

Tips & common mistakes

Quick tips

1 Wh = 3600 J = 0.001 kWh.
Battery mAh × V = Wh. A 3000 mAh phone battery at 3.7 V = 11.1 Wh.
Airline limits lithium batteries to 100 Wh for carry-on.

Avoid these

Confusing mAh with Wh — need voltage to convert.
Using Wh when kWh is more appropriate for large batteries.
Forgetting the voltage in battery capacity calculations.

Frequently asked questions

How many therms in a watt-hour?

One watt-hour equals 3.4121e-5 therms.

How do I convert watt-hours to therms?

Multiply the watt-hour value by 3.4121e-5 to get the equivalent in therms.

What is 100 watt-hours in therms?

100 watt-hours equals 0.003412 therms.

Is a watt-hour bigger than a therm?

No. 1 watt-hour equals 3.4121e-5 therms, so one watt-hour is smaller.

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

Multiply by 0 for a quick estimate; use a calculator for precise results.

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