Battery charge converter
Converts battery charge between mAh, Ah, and coulombs, and to watt-hours at a stated voltage.
5,000 mAh is 5 Ah.
- Input
- Energy
Provenance
- Computed by
- units.charge.convert 1.0.0, core 0.1.0
- Model
- Exact unit definitions; energy = charge × nominal voltage
- Accuracy
- Exact to double precision for charge. Energy is as accurate as the nominal voltage, which varies with state of charge
- Notes
- None
- Cites
- National Institute of Standards and Technology, Guide for the Use of the International System of Units (SI), NIST Special Publication 811
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Exact unit definitions; energy = charge × nominal voltage
Accuracy: Exact to double precision for charge. Energy is as accurate as the nominal voltage, which varies with state of charge
When to use this: Use this for a battery capacity that has to cross units, and for the watt-hour figure a shipping rule or a spec sheet asks for: a 5,000 mAh pack in ampere hours, or in watt hours once you give it the pack's nominal voltage.
Limitations: A charge is not an energy. The watt-hour figure is charge times the nominal voltage you supply, which is a convention for the pack rather than a measurement -- the real voltage falls as the pack discharges, so the delivered energy is typically a few percent either side and is reported to four significant figures for that reason. Give no voltage and no energy is reported, which is the honest answer rather than a guess. Nothing here knows about chemistry, C-rate, temperature or state of health, all of which change what a pack actually delivers.
Worked example: A 5,000 mAh 6S pack (22.2 V) in Ah and Wh. Source: Exact unit definitions (NIST SP 811 Appendix B).
You enter
- To unit
- Ah
- Charge
- 5000 mAh
- Voltage
- 22.2 V
You get
- Converted
- 5 Ah
- Input
- 5,000 mAh
- Energy
- 111 Wh
Review: Not yet independently reviewed by a metrologist.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 22 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, National Institute of Standards and Technology, 2008 edition. Appendix B.8, Factors for units listed alphabetically.