A = W / V
1000 W at 12 V is about 83 A; the same 1000 W at 230 V is just over 4 A.
Calculator
Watts to amps calculator
Pick your voltage and enter watts or amps. The result is the current you use for the rest of your wire size and fuse calculations.
- Free, no account needed
- 12V, 24V, 48V and 230V
- Result while you type
- Carries over into your diagram
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System voltage
The result is guidance based on your input. Manufacturer instructions and local regulations always take precedence; you remain responsible for the installation.
Why current matters more than watts
Cables and fuses are chosen on amps, not watts. The same power draws four times the current at 12 V as it does at 48 V, and therefore a far thicker cable. That makes this conversion almost always the first step.
W = V × A
If the label only lists a current, this gives you the power.
Losses count
A 230V load behind an inverter draws more on the battery side than this conversion suggests: include the inverter efficiency.
From calculation to complete diagram
Designing a complete electrical system? In WireElectric you do not convert per load: the app knows the power of each component and works out the current per connection itself.
You can start drawing without an account.
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Questions about watts and amps
- How many amps is 1000 watts at 12V?
- About 83 A: 1000 W divided by 12 V. At 24 V that is roughly 42 A and at 230 V just over 4 A.
- Does A = W / V also apply to 230V?
- For a purely resistive load, yes. Motors and switching supplies add a power factor, which makes the actual current higher.
- Which current do I use for my cable and fuse?
- The continuous current of the load, with margin for inrush. Enter that value in the wire size or fuse calculator.
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