Watt Hours to Joules Converter

Convert watt hours to joules instantly with our free online tool. Perfect for batteries, power banks, and electronics. Get accurate Wh to J results.

Energy Converter

1 wh = 3600 j

The quick answer for 1 Watt Hours — type any value below for the exact result

Enter Watt Hours

Watt Hours

Result in Joules

Joules

Wh to J Conversion Formula

To convert watt hours to joules, multiply the Wh value by 3600. One watt hour is the energy of one watt running for 3600 seconds, and since one watt-second equals one joule, the factor is exactly 3600 — a clean definition-based conversion.

1 wh = 3600 j

Watt Hours and Joules Explained

Watt Hours (wh)

The watt hour (Wh) is the energy delivered by one watt of power over one hour, equal to exactly 3600 joules. It is the honest unit for battery capacity because it accounts for voltage, unlike milliamp-hours: a 15 Wh phone battery and a 15 Wh laptop cell carry identical energy despite different mAh ratings. Scales run from 0.7 Wh coin cells through 500 Wh e-bike packs to home batteries in the thousands of Wh.

Where it is used: Standard on battery labels, power bank specs, airline lithium regulations (100 Wh and 160 Wh limits), and energy-density datasheets.

Origin: Companion of the kilowatt hour, devised by early electric utilities in the 1880s to bill energy as power multiplied by time; battery makers kept the smaller watt-hour scale.

Joules (j)

The joule (J) is the SI unit of energy — one watt-second, or the work of one newton over one meter. One watt hour is 3600 J, a smartphone battery about 54,000 J, and a gallon of gasoline roughly 120 million J. Physics equations, chemistry thermochemistry, and engineering simulations all require joules, which is why battery specs in Wh eventually need translating for any SI-based calculation.

Where it is used: Universal across science and engineering; required whenever battery energy enters formulas involving force, heat, velocity, or electrical work in SI form.

Origin: Named for James Prescott Joule, whose experiments in the 1840s unified heat and mechanical energy; the watt-second relationship makes his unit the natural partner of electrical measurement.

Watt Hours to Joules Conversion Table

Watt Hours (wh)	Joules (j)
0.1 wh	360 j
0.25 wh	900 j
0.5 wh	1800 j
1 wh	3600 j
2 wh	7200 j
5 wh	18000 j
10 wh	36000 j
15 wh	54000 j
20 wh	72000 j
50 wh	180000 j
74 wh	266400 j
100 wh	360000 j
200 wh	720000 j
500 wh	1.800000e+6 j
1000 wh	3.600000e+6 j

Joules to Watt Hours Conversion Table

Joules (j)	Watt Hours (wh)
100 j	0.0277777778 wh
500 j	0.1388888889 wh
1000 j	0.2777777778 wh
3600 j	1 wh
5000 j	1.3888888889 wh
10000 j	2.7777777778 wh
36000 j	10 wh
54000 j	15 wh
100000 j	27.7777777778 wh
360000 j	100 wh
1.000000e+6 j	277.7777777778 wh
3.600000e+6 j	1000 wh

Watt Hours to Joules in Everyday Objects

Common real-world examples that make Watt Hours and Joules easy to picture at a glance.

	Watt Hours (wh)	Joules (j)
A CR2032 coin cell	0.7 wh	2520 j
A AA alkaline battery	3.9 wh	14040 j
Charging a smartphone	15 wh	54000 j
A laptop battery	52.6 wh	189360 j
A 20,000 mAh power bank	74 wh	266400 j
An e-bike battery	500 wh	1.800000e+6 j
The airline lithium limit	100 wh	360000 j

When You Need Watt Hours to Joules Conversions

Power Bank Flight Compliance

Airline lithium rules cap carry-on batteries at 100 Wh. Converting that ceiling to 360,000 J and a 74 Wh bank to 266,400 J shows exactly how much margin remains before approval paperwork kicks in.

IoT Device Power Budgets

Embedded engineers size coin cells in joules to match firmware energy-per-transmission figures. A CR2032's 0.7 Wh becomes 2520 J; a radio burst costing 5 J leaves room for about 500 sends before the cell fades.

Drone Flight-Time Engineering

Drone builders mix Wh pack labels with SI motor power draws in watts. A 52.6 Wh pack (189,360 J) against a 260 W hover load predicts roughly 12 minutes of flight, verified before any bench test.

Comparing Battery Chemistries

Datasheets quote energy density in Wh/kg while research papers use J/kg. An alkaline AA at about 3.9 Wh per 23 g cell translates to 14,040 J — directly stackable against Li-ion chemistry tables in SI units.

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How to Use

1

Enter Watt Hours

Type the Wh value from a battery label or datasheet — common entries include 0.7 for a CR2032 coin cell, 15 for a smartphone, and 74 for a 20,000 mAh power bank
2

View Joules

The SI equivalent appears instantly: a 52.6 Wh laptop battery converts to 189,360 J, ready for physics-style energy calculations
3

Copy or Swap

Copy the result or click Swap to convert joules back to watt hours for reverse checks
4

Estimate Runtime

Use the joule figure in power budgets: a device drawing 0.5 W consumes 1800 J per hour, so a 54,000 J (15 Wh) charge runs it for about 30 hours before efficiency losses

Why Use Be Converter?

Instant Conversion

Get precise Wh to joule results in real-time as you type — ideal for battery comparisons and runtime estimates

Exact 3600 Factor

Because 1 Wh = 3600 J by definition, values like 10 Wh always convert to exactly 36,000 J with no rounding at all

Conversion Table

Quick reference across battery sizes — 0.7 Wh coin cell (2520 J), 15 Wh phone charge (54,000 J), 74 Wh power bank (266,400 J), and 1000 Wh (3,600,000 J)

Bidirectional

Easily swap between watt hours and joules with one click when checking datasheets against SI calculations

Free & No Signup

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Frequently Asked Questions

How many joules are in 1 watt hour?

1 watt hour equals exactly 3600 joules — one watt sustained for 3600 seconds, with each watt-second being one joule. In reverse, 1 joule is 1/3600 Wh, about 0.000278 Wh.

How do I convert 100 Wh to joules?

Multiply by 3600: 100 × 3600 = 360,000 J (360 kJ). 100 Wh is also the FAA carry-on limit for lithium batteries, so that ceiling equals a hard 360,000 J of stored energy.

Why do batteries use Wh instead of joules?

Watt hours pair naturally with the watts that devices draw, making runtime mental math easy — a 10 Wh cell runs a 1 W gadget for ten hours. Physics equations, though, need SI joules, and 1 Wh = 3600 J bridges the two views exactly.

How do I convert mAh to watt hours first?

Multiply milliamp-hours by voltage and divide by 1000: a 3000 mAh phone battery at 3.7 V is 11.1 Wh. Then convert to joules: 11.1 × 3600 = 39,960 J. mAh alone cannot cross to energy without the voltage.

Is a watt hour bigger than a joule?

Much bigger — 1 Wh = 3600 J, a factor of 3600 from the seconds in an hour. So converting Wh to J should always enlarge the number roughly 3600-fold; anything else means a slipped factor or unit.

How many joules is a 20,000 mAh power bank?

A 20,000 mAh bank at 3.7 V stores 74 Wh, which is 74 × 3600 = 266,400 J. After voltage conversion losses it delivers roughly 50 Wh usable — about 180,000 J to your devices.

What is 1 kWh in watt hours and joules?

1 kWh = 1000 Wh = 3,600,000 J. The kilowatt hour is simply a thousand watt hours, so the same 3600 factor cascades: 1000 × 3600 = 3.6 million joules, matching every electricity meter.

Do drone and RC hobby packs use Wh?

Yes, and airline rules cap them in Wh too. A typical 4S 5000 mAh drone pack at 14.8 V holds 74 Wh (266,400 J); spare packs above 100 Wh (360,000 J) need airline approval, and 160 Wh is the usual hard ceiling.

About Watt Hours to Joules Converter

Our free online watt hours to joules converter provides instant, accurate energy conversions for batteries, power banks, and electronics design. The watt hour is the battery industry's favorite unit — capacity labels, airline lithium limits, and energy-density specs all quote Wh, because it compares fairly across voltages. The joule is the SI unit every physics formula and engineering simulation expects. The conversion is exact by definition: 1 Wh = 3600 J. Whether you are computing stored energy in joules for a power budget, checking a power bank against the 100 Wh flight limit, or turning mAh-and-voltage specs into SI energy, this tool handles it in one step.

Expert Tips for Wh to J Conversion

The factor 3600 is exact (3600 seconds per hour, one joule per watt-second). Scale it freely: 1 Wh = 3600 J, 1 kWh = 3,600,000 J, 1 mWh = 3.6 J.

Battery benchmarks in joules: CR2032 coin cell 0.7 Wh = 2520 J, AA alkaline about 3.9 Wh = 14,040 J, smartphone 15 Wh = 54,000 J, MacBook-class laptop 52.6 Wh = 189,360 J.

Travel rule: the 100 Wh lithium limit equals 360,000 J and the 160 Wh ceiling is 576,000 J. Converting to joules makes the safety margin tangible when stacking spare packs.

Runtime math in SI: a sensor drawing 10 mW uses 36 J per hour, so a 2520 J coin cell (0.7 Wh) theoretically lasts 70 hours — derate 20-30% for real quiescent draw.

Energy-density comparisons: gasoline at about 12,700 Wh/kg (45.7 million J/kg) versus a Li-ion pack near 250 Wh/kg (900,000 J/kg) — the 50-fold gap is why electric range is hard.