How many watt-hours are in 1 joule?

1 J equals 0.0002777777778 Wh. This is an exact conversion factor defined by NIST.

How do I convert joules to watt-hours?

Multiply the value in J by the conversion factor. For example, 10 J = 0.002777777778 Wh. Use our calculator above for instant results.

Is the joules to watt-hours conversion exact?

Yes, this conversion is mathematically exact based on the international definition of these units (NIST SP 811).

Can I convert joules to watt-hours offline?

Yes! OmniConvert runs entirely in your browser — no internet connection needed after the page loads. Your data never leaves your device, ensuring complete privacy.

What is the difference between joules and watt-hours?

Joules (J) and Watt-hours (Wh) are both units of energy but belong to different measurement systems. 1 J = 0.0002777777778 Wh. Use the converter above to switch between them instantly.

Joules to Watt-hours (J → Wh) — Free Online Converter

J → Wh Reference Table

J	Wh
0.001 J	2.777777778e-7 Wh
0.002 J	5.555555556e-7 Wh
0.003 J	8.333333333e-7 Wh
0.004 J	0.000001111111111 Wh
0.005 J	0.000001388888889 Wh
0.006 J	0.000001666666667 Wh
0.007 J	0.000001944444444 Wh
0.008 J	0.000002222222222 Wh
0.009 J	0.0000025 Wh
0.01 J	0.000002777777778 Wh
0.02 J	0.000005555555556 Wh
0.03 J	0.000008333333333 Wh
0.04 J	0.00001111111111 Wh
0.05 J	0.00001388888889 Wh
0.06 J	0.00001666666667 Wh
0.07 J	0.00001944444444 Wh
0.08 J	0.00002222222222 Wh
0.09 J	0.000025 Wh
0.1 J	0.00002777777778 Wh
0.2 J	0.00005555555556 Wh
0.3 J	0.00008333333333 Wh
0.4 J	0.0001111111111 Wh
0.5 J	0.0001388888889 Wh
0.6 J	0.0001666666667 Wh
0.7 J	0.0001944444444 Wh
0.8 J	0.0002222222222 Wh
0.9 J	0.00025 Wh
1 J	0.0002777777778 Wh
1.5 J	0.0004166666667 Wh
2 J	0.0005555555556 Wh
2.5 J	0.0006944444444 Wh
3 J	0.0008333333333 Wh
3.5 J	0.0009722222222 Wh
4 J	0.001111111111 Wh
4.5 J	0.00125 Wh
5 J	0.001388888889 Wh
5.5 J	0.001527777778 Wh
6 J	0.001666666667 Wh
6.5 J	0.001805555556 Wh
7 J	0.001944444444 Wh
7.5 J	0.002083333333 Wh
8 J	0.002222222222 Wh
8.5 J	0.002361111111 Wh
9 J	0.0025 Wh
9.5 J	0.002638888889 Wh
10 J	0.002777777778 Wh
11 J	0.003055555556 Wh
12 J	0.003333333333 Wh
13 J	0.003611111111 Wh
14 J	0.003888888889 Wh
15 J	0.004166666667 Wh
16 J	0.004444444444 Wh
17 J	0.004722222222 Wh
18 J	0.005 Wh
19 J	0.005277777778 Wh
20 J	0.005555555556 Wh
25 J	0.006944444444 Wh
30 J	0.008333333333 Wh
35 J	0.009722222222 Wh
40 J	0.01111111111 Wh
45 J	0.0125 Wh
50 J	0.01388888889 Wh
55 J	0.01527777778 Wh
60 J	0.01666666667 Wh
65 J	0.01805555556 Wh
70 J	0.01944444444 Wh
75 J	0.02083333333 Wh
80 J	0.02222222222 Wh
85 J	0.02361111111 Wh
90 J	0.025 Wh
95 J	0.02638888889 Wh
100 J	0.02777777778 Wh
120 J	0.03333333333 Wh
125 J	0.03472222222 Wh
130 J	0.03611111111 Wh
140 J	0.03888888889 Wh
150 J	0.04166666667 Wh
160 J	0.04444444444 Wh
175 J	0.04861111111 Wh
180 J	0.05 Wh
200 J	0.05555555556 Wh
225 J	0.0625 Wh
250 J	0.06944444444 Wh
275 J	0.07638888889 Wh
300 J	0.08333333333 Wh
350 J	0.09722222222 Wh
400 J	0.1111111111 Wh
450 J	0.125 Wh
500 J	0.1388888889 Wh
600 J	0.1666666667 Wh
700 J	0.1944444444 Wh
750 J	0.2083333333 Wh
800 J	0.2222222222 Wh
900 J	0.25 Wh
1000 J	0.2777777778 Wh
1200 J	0.3333333333 Wh
1250 J	0.3472222222 Wh
1500 J	0.4166666667 Wh
1750 J	0.4861111111 Wh
2000 J	0.5555555556 Wh
2500 J	0.6944444444 Wh
3000 J	0.8333333333 Wh
4000 J	1.111111111 Wh
4500 J	1.25 Wh
5000 J	1.388888889 Wh
6000 J	1.666666667 Wh
7000 J	1.944444444 Wh
7500 J	2.083333333 Wh
8000 J	2.222222222 Wh
9000 J	2.5 Wh
10000 J	2.777777778 Wh
15000 J	4.166666667 Wh
20000 J	5.555555556 Wh
25000 J	6.944444444 Wh
50000 J	13.88888889 Wh
75000 J	20.83333333 Wh
100000 J	27.77777778 Wh

Values based on NIST SP 811 conversion factors

Why Convert Joules to Watt-hours?

Converting between joules (J) and watt-hours (Wh) is one of the most common energy conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert J to Wh saves time and prevents errors.

Energy conversions from J to Wh are crucial for dietitians, physicists, and engineers. In nutrition, understanding the link between calories and joules helps individuals manage their diet and energy intake effectively. In the power sector, converting between kilowatt-hours and British Thermal Units (BTU) is necessary for sizing heating and cooling systems for homes and offices. Physicists rely on precise energy unit conversions to calculate work, heat, and thermodynamic processes. Whether tracking fitness goals or analyzing home energy bills, accurate conversion empowers users to make better health and financial decisions.

How to Convert Joules to Watt-hours

To convert joules to watt-hours, use the following formula:

Wh = J × 0.0002777777778

Example: 1 J = 0.0002777777778 Wh

For example, 5 J = 0.001388888889 Wh, 10 J = 0.002777777778 Wh, and 100 J = 0.02777777778 Wh. For larger values, 1000 J = 0.2777777778 Wh. Conversely, 1 Wh = 3600 J. Our calculator above performs this conversion instantly with full precision — no rounding errors.

Common Mistakes to Avoid

Calorie confusion: Food 'Calories' are actually kilocalories (kcal).
Joule scale: 1 kWh is 3.6 million Joules (orders of magnitude difference).
Power vs Energy: mixing up Watts (power) and Watt-hours (energy).

Pro Tips

Food labels: Learn to read kcal; average adult needs ~2000 kcal/day.
Battery capacity: Wh = V * Ah. Useful for comparing different voltage batteries.
Efficiency: Energy cannot be created/destroyed, only converted (with some loss as heat).

What is a Joule?

The joule (J) is the SI derived unit of energy. Defined as the work done by a force of one newton displacing an object by one meter.

Joules are used in science and engineering to measure work, energy, and heat. In nutrition, kilojoules (kJ) are used in many countries instead of calories.

What is a Watt-hour?

A unit of energy equivalent to one watt of power expended for one hour.

Used for battery capacity.

Joules → Watt-hours

Joules to Watt-hours Formula