Battery Runtime Calculator
Converts Ah·V·DoD·efficiency into usable watt-hours, then divides by load watts for hours.
Limitation: Educational estimate only.
How to Use the Battery Runtime Calculator
Enter the fields below, then review the educational estimate.
Enter battery Ah and nominal voltage.
Peukert & temperature
High discharge rates and cold temperatures reduce real capacity. This model is linear and optimistic.
What This Calculator Estimates
Linear watt-hour runtime for planning camping, UPS, and DIY power stations—not BMS firmware.
Worked Examples
100 Ah 12 V, 100 W, DoD 0.8, η 0.9
Inputs
Result
Usable Wh = 100·12·0.8·0.9 = 864; 864/100 = 8.64 h.
Safety first
De-energize circuits before measuring. When in doubt, stop and consult a licensed electrician.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorFormulas & Assumptions
Transparent educational arithmetic. Not NEC design software or a wiring permit.
Formula
Usable energy
Wh = Ah · V · DoD · η
Runtime
hours = Wh / load_W
Scientific Background
Lead-acid and lithium chemistries differ in recommended DoD. Inverter efficiency varies with load. Peukert’s law is not applied.
Sources & review
Battery Runtime Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.
Last reviewed
July 22, 2026
Reference
physics.nist.gov
https://physics.nist.gov/cuu/Constants/index.htmlReference
nist.gov
https://www.nist.gov/pml/owm/wire-gauge-and-current-carrying-capacityFree Calculator Hub methodology
Free Calculator Hub
/methodology
See our methodology and corrections policy.