Runtime vs surge: what matters and when
Understand average load vs startup surges. Use the right calculator for sizing vs estimating runtime.
Quick take
Use these quick rules to get a reliable answer, then fine‑tune with the calculators linked below.
How to use the calculator
- Open the calculator linked below.
- Enter the numbers that match your setup.
- Use our rules of thumb to sanity-check the result.
Rules of thumb
- LiFePO₄ inverters are ~85–92% efficient.
- Fridges average 40–70W but spike 400–1200W for a second.
- Runtime = (Wh × efficiency) ÷ average W.