Watt to Joule/s Converter
Enter the value that you want to convert watt (W) to joule/s (J/s) or joule/s to watt.Also written as W to J/S conversion.
1 watt = 1.0000000 joule/s
Formula: joule/s = watt value × 1.0000000
W to J/S — watt to joule/s
10 watt = 10.00000 joule/s
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Watt to Joule/s: The Essentials
About the Watt
Watt (W) is a unit of power measurement. 1 watt is equal to 1.0000000 joule/s.
What is Joule/s?
Joule/s (J/s) is a unit of power measurement. 1 joule/s is equal to 1.0000000 watt.
Power Measurement Across Applications
Power units span from milliwatts in electronics to megawatts in power plants. Engine output is still quoted in horsepower (mechanical, metric, and electrical — all slightly different). HVAC systems rate cooling in tons of refrigeration or BTU/hour. Solar panels specify watts peak. Electric motors list watts or kilowatts. Each industry carries its historical unit preferences, making conversion between them a daily necessity.
watt to joule/s metric conversion table
| 0.01 W | = | 0.01000 J/s |
| 0.1 W | = | 0.10000 J/s |
| 1 W | = | 1.00000 J/s |
| 2 W | = | 2.00000 J/s |
| 3 W | = | 3.00000 J/s |
| 4 W | = | 4.00000 J/s |
| 5 W | = | 5.00000 J/s |
| 6 W | = | 6.00000 J/s |
| 7 W | = | 7.00000 J/s |
| 8 W | = | 8.00000 J/s |
| 9 W | = | 9.00000 J/s |
| 10 W | = | 10.00000 J/s |
| 11 W | = | 11.00000 J/s |
| 12 W | = | 12.00000 J/s |
| 13 W | = | 13.00000 J/s |
| 14 W | = | 14.00000 J/s |
| 15 W | = | 15.00000 J/s |
| 16 W | = | 16.00000 J/s |
| 17 W | = | 17.00000 J/s |
| 18 W | = | 18.00000 J/s |
| 19 W | = | 19.00000 J/s |
| 20 W | = | 20.00000 J/s |
| 30 W | = | 30.00000 J/s |
| 40 W | = | 40.00000 J/s |
| 50 W | = | 50.00000 J/s |
| 60 W | = | 60.00000 J/s |
| 70 W | = | 70.00000 J/s |
| 80 W | = | 80.00000 J/s |
| 90 W | = | 90.00000 J/s |
| 100 W | = | 100.00000 J/s |
| 200 W | = | 200.00000 J/s |
| 300 W | = | 300.00000 J/s |
| 400 W | = | 400.00000 J/s |
| 500 W | = | 500.00000 J/s |
| 600 W | = | 600.00000 J/s |
| 700 W | = | 700.00000 J/s |
| 800 W | = | 800.00000 J/s |
| 900 W | = | 900.00000 J/s |
| 1000 W | = | 1000.00000 J/s |
How to Convert W to J/S (Watt to Joule/s)?
We can convert watt to joule/s by using an example.
Example:
Convert 20 Watt to Joule/s?
We know 1 Watt = 1.0000000 joule/s; 1 Joule/s = 1.0000000 watt.
20 watt = ___J/s
20 × 1.0000000 = 20.00000 J/s (we know 1 watt = 1.0000000 joule/s)
Answer:
20 watt = 20.00000 joule/s
Watts and Joules per Second: Understanding They Are the Same Unit
One watt is defined as exactly one joule per second (1 W = 1 J/s). They are not just equivalent — they are the same physical quantity expressed two ways. The watt is a derived SI unit created specifically to represent the rate of energy transfer of one joule every second. This conversion exists because some physics problems express power in J/s while engineering uses watts.
- Recognize that watts and joules per second are identical by definition.
- The numeric value in watts equals the numeric value in J/s.
- No multiplication or division is needed.
- Simply relabel: 500 W = 500 J/s.
Power Expressed as Watts and Joules per Second
These are the same values with different unit labels — shown to illustrate the 1:1 relationship:
| Watt | Joule/s |
|---|---|
| 1 W | 1 J/s |
| 60 W | 60 J/s |
| 100 W | 100 J/s |
| 500 W | 500 J/s |
| 1,000 W | 1,000 J/s |
| 2,000 W | 2,000 J/s |
| 100,000 W | 100,000 J/s |
Solved Examples: Watts and Joules per Second
Question 1: A laser outputs 5 W of power. How many joules of energy does it deliver per second?
Solution:
Since 1 W = 1 J/s by definition:
5 W = 5 J/s
Answer: The laser delivers 5 joules of energy every second.
Question 2: A physics experiment measures heat flow at 350 J/s. Express as watts.
Solution:
1 J/s = 1 W (identical units)
350 J/s = 350 W
Answer: The heat flow rate is 350 W.
Question 3: A runner expends energy at 800 J/s during sprinting. What is their power output in watts?
Solution:
Power in watts = energy rate in J/s
800 J/s = 800 W
Answer: The runner produces 800 W of power — comparable to a professional cyclist at peak effort.
Quick Check: Watts and J/s Equivalence
Try solving these on your own to test your understanding:
- A motor outputs 2,200 J/s. What is that in watts? (Answer: 2,200 W)
- Express 45 W in joules per second. (Answer: 45 J/s)
- A chemical reaction releases energy at 150 J/s. Convert to watts. (Answer: 150 W)
- A phone charger delivers 18 W. How many J/s is that? (Answer: 18 J/s)
- An industrial heater produces 50,000 J/s. Express in kW. (Answer: 50 kW)
Why Both Units Exist
The joule per second explicitly shows power as "energy per time" which is useful in thermodynamics and physics derivations where you need to track energy flow. The watt is a convenient shorthand used in electrical engineering, product labels, and everyday life. Both are valid SI representations — the watt is simply the special name assigned to J/s to honor James Watt.
Connecting Watts to Other Energy Rates
While W and J/s are identical, other energy-rate units require conversion: 1 calorie/second = 4.184 W, 1 BTU/hour = 0.2931 W, and 1 kcal/minute = 69.78 W. The joule-per-second foundation helps you understand these conversions: they all describe how quickly energy moves, just measured in different energy units divided by different time units.
Key Takeaways
- 1 watt ≡ 1 joule per second — they are the same unit by definition.
- No multiplication or division needed; just relabel.
- Physics texts often use J/s to emphasize energy flow rate.
- Engineering and product labels use watts for convenience.
- The watt is the special SI name for the derived unit kg·m²·s⁻³ = J/s.
Watt to Joule/s Conversion Formula
joule/s = watt × 1.0000000
1 watt = 1.0000000 joule/s
1 joule/s = 1.0000000 watt
Reverse: watt = joule/s × 1.0000000
Frequently Asked Questions
How many joule/s are in 1 watt?
There are 1.0000000 joule/s in 1 watt. To convert watt to joule/s, multiply the value by 1.0000000.
How do I convert watt to joule/s?
Multiply your watt value by 1.0000000 to get the equivalent in joule/s. For example, 5 watt = 5 × 1.0000000 = 5.00000 joule/s.
How do I convert joule/s to watt?
Multiply your joule/s value by 1.0000000 to get the equivalent in watt. Alternatively, divide by 1.0000000.
What is 10 watt in joule/s?
10 watt is equal to 10.00000 joule/s.
What is 100 watt in joule/s?
100 watt is equal to 100.00000 joule/s.