Calculating your inverter size needed is straightforward once you know the Inverter Size formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Inverter Size Calculator.
What is Inverter Size?
The Inverter Size calculation tells you your inverter size needed from a few simple inputs. The figure you are solving for here is the inverter size needed.
The Inverter Size formula
The core formula is:
Inverter size needed = Total load ÷ Power factorHere is what each input means:
- Total load — a value measured in W. Example: 800 W.
- Power factor — a number. Example: 0.8.
How to calculate it step by step
- Write down the total load (for example, 800 W).
- Write down the power factor (for example, 0.8).
- Apply the formula above to get your inverter size needed.
- Double-check the result with the Inverter Size Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Total load | 800 W |
| Power factor | 0.8 |
| Inverter size needed | 1,000 |
With total load of 800 W and power factor of 0.8, the inverter size needed works out to 1,000.
Example 2
With total load of 1,600 W and power factor of 0.8, the inverter size needed works out to 2,000.
| Result | Value |
|---|---|
| Inverter size needed | 2,000 |
Example 3
With total load of 400 W and power factor of 0.8, the inverter size needed works out to 500.
| Result | Value |
|---|---|
| Inverter size needed | 500 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Inverter Size Calculator does it instantly, for free, with the formula and a worked example built in.
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