Battery Runtime Calculator

Estimate runtime, usable energy and average electrical power from battery capacity, voltage and load current.

A simple constant-load runtime estimate for batteries powering electronics, sensors and bench systems.

Start here

  1. Enter battery voltage and capacity, then the load current.
  2. Set the available capacity and conversion efficiency for your setup.
  3. Choose Calculate to read usable energy, load power and estimated runtime.
How to read the results

This uses a constant load. Use the electric UAS endurance calculator for flight reserve and propulsion planning.

Local calculation: values are processed in your browser. Calculation inputs are not transmitted. Optional profiles are stored only in this browser.
Optional aircraft profile: Manual values
Active profile: Manual values
mAh
V
mA
%
The fraction of nameplate capacity you intend to use.
%
Allow for regulator, wiring and conversion losses.

Planning output only. Verify assumptions and results against authoritative data, manufacturer information, approved procedures, test evidence and competent engineering or regulatory review before use.

Calculation basis

Nominal energy is capacity in amp-hours multiplied by nominal voltage. Usable energy applies the entered usable-capacity and conversion-efficiency factors. Estimated runtime is usable capacity divided by average load current.

Limitations and verification

  • Assumes a constant average current and nominal voltage.
  • Does not model voltage sag, discharge-rate effects, temperature, ageing, cell imbalance or battery-management cut-off behaviour.
  • Nameplate capacity should be replaced with measured capacity where evidence is available.

Version and review status

Formula set: v1.2
Staging review date: 17 August 2026
Status: Staging beta pending user acceptance and cross-browser checks.

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