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Single conversion
To convert from Joule (J) to Watt-second (Ws), use the following formula:
Let's convert 5 Joule (J) to Watt-second (Ws).
Using the formula:
Therefore, 5 Joule (J) is equal to Watt-second (Ws).
Here are some quick reference conversions from Joule (J) to Watt-second (Ws):
| Joules | Watt-seconds |
|---|---|
| 0.000001 J | Ws |
| 0.001 J | Ws |
| 0.1 J | Ws |
| 1 J | Ws |
| 2 J | Ws |
| 3 J | Ws |
| 4 J | Ws |
| 5 J | Ws |
| 6 J | Ws |
| 7 J | Ws |
| 8 J | Ws |
| 9 J | Ws |
| 10 J | Ws |
| 20 J | Ws |
| 30 J | Ws |
| 40 J | Ws |
| 50 J | Ws |
| 100 J | Ws |
| 1000 J | Ws |
| 10000 J | Ws |
For all Energy converters, choose units using the From/To dropdowns above.
The joule (J), as part of the International System of Units (SI), is a fundamental unit used to measure energy.
Whether you're discussing the electricity that powers your home, the work done by a machine, or the energy you get from food, the joule is the universal standard.
Key Takeaways:
A joule (J) represents the amount of work done when a force of one newton moves an object by one meter.
This is formally expressed as:
1 J = 1 N·m
To make that simpler, think of it this way: lifting a small apple (which weighs about one newton) one meter straight up requires about one joule of energy.
This direct link between force, distance, and energy makes the joule a cornerstone unit in physics and engineering.
It's easy to mix up joules and watts, but the key difference is time.
Specifically, one watt is equal to one joule of energy transferred per second (1 W = 1 J/s).
For example, a 100-watt light bulb uses 100 joules of electrical energy every second it is on.
While many food labels use calories (specifically kilocalories, or kcal), the official SI unit for food energy is the joule.
The conversion is straightforward:
1 food calorie (kcal) ≈ 4,184 joules or 4.184 kilojoules (kJ)
Using joules and kilojoules (kJ) provides a universal, scientific standard for measuring the energy we get from food. This is why you will often see "kJ" on nutrition labels in many parts of the world.
A Watt-second (Ws) is a unit of energy in the International System of Units (SI), equal to exactly one Joule (J).
It is a fundamental measurement used to quantify energy transfer, especially in fields like physics and photography.
The relationship is simple: one Watt-second is precisely equal to one Joule.
This 1:1 equivalence means the two units are entirely interchangeable. So, if you have 100 Ws of energy, you also have 100 J of energy.
This makes it a straightforward and reliable unit for any precise energy calculation.
In photography, the Watt-second is the standard for measuring the maximum energy output of a studio strobe or electronic camera flash.
Essentially, a higher Watt-second rating means a more powerful flash.
For example, a 500 Ws strobe has more flash power than a 200 Ws unit, allowing it to produce a much brighter burst of light.
This extra power is crucial for illuminating larger scenes or overpowering ambient light, like bright sunshine.
The name "Watt-second" perfectly describes its own formula.
It is the amount of energy used when one Watt of power is applied for exactly one second.
This gives us the fundamental equation for energy transfer:
Energy (Ws) = Power (W) × Time (s)
To sum up, while the Watt-second is a universal unit of energy equivalent to a Joule, its most common practical use is in photography.
When choosing a studio strobe or camera flash, a higher Ws rating gives you more lighting power, offering greater creative control over your shots.