Cuts Per Charge Calculator
Estimate how many cuts a cordless saw will make on one charge.
Estimate how many cuts you'll get from one charge with a cordless saw. Time one typical cut with your phone's stopwatch, and the calculator does the rest using the pack's energy: Ah × V = Wh. Everything is worked out in your browser. Nothing is saved or sent anywhere.
1. Your battery pack
Use the voltage and amp-hour rating printed on the pack. "Max" voltages (such as 20V Max) are the fully charged figure; the nominal voltage is lower and is what's used here.
100% for a new pack. An older pack might hold 70–80%.
2. Your saw and your cuts
A guess for the saw's draw is fine. Hardwood, wet timber, deep cuts and a blunt blade all push it up.
Roughly 400–900 W for a 165–185mm cordless circular saw under load.
Time one typical cut from start to finish.
Blade spinning before and after the cut.
3. Results
How it was worked out
What this does and doesn't tell you
- This is an idealised estimate. Real cuts per charge are usually fewer, especially with small packs, cold weather, heavy cuts and older packs.
- Under heavy load a small pack's voltage sags and it may cut out early to protect itself, well before its full energy is used.
- Run-up time uses less power than cutting. This calculator counts it at 30% of the cutting draw.
- Lithium-ion tool packs can short, overheat and catch fire if they're damaged, wired wrongly or charged on the wrong charger. Only use the maker's charger for the pack, and recycle any pack that is swollen, burnt, leaking, crushed or has been in water.
Next steps
Read Cordless Circular Saw: What Pack Size Do You Need?, or work out a recharge with the Pack Charge Time Calculator.