Wh to mAh Calculator

Convert Wh and mAh with explicit nominal voltage, reverse-solve the relationship, compare battery/pack scenarios and model delivered energy without hiding assumptions.

Wave118 · solve + voltage model + scenarios + audit + export

Battery Energy & Charge Studio

Convert watt-hours and milliamp-hours without hiding the voltage assumption. Reverse-solve any one of Wh, mAh or V, compare chemistry/pack voltages, model conversion efficiency, and keep a local evidence trail.

3-way Wh · mAh · V solverEnergy/charge unit normalizationChemistry + series-cell presetsVoltage sensitivity tableEfficiency/output scenarioCSV + Project JSON + local history

Solve forEnergy

Charge

Nominal voltage

PrecisionModel

Battery chemistry / cellSeries cells

Enter the pack nominal voltage directly.

Same Wh across common voltages

This table keeps energy fixed and shows why mAh cannot be compared fairly across different nominal voltages.

Voltage	Typical context	Equivalent mAh	Ah	Round-trip Wh

Voltage sensitivity audit

See the mAh impact if the chosen nominal voltage is 5–10% lower or higher. This is not a discharge-curve simulation.

Scenario	Voltage	Equivalent mAh	vs entered

Conversion/output scenario

Efficiency %Output voltage VOptional load W

Portable evidence

Project JSON includes the current numeric inputs/settings. The settings-only share link deliberately excludes Wh, mAh, voltage values and history.

Saved conversions

Nothing is saved until you choose “Save result locally.” Up to 12 conversions stay only in this browser.

How to use Wh and mAh without mixing unlike battery ratings

Voltage is not optional

Wh measures energy while mAh measures charge. The bridge is voltage: mAh = Wh × 1,000 ÷ V. Use the battery or pack’s stated nominal voltage when comparing label ratings.

Series cells change pack voltage

For a simple series model, nominal pack voltage is nominal cell voltage multiplied by the number of cells in series. Parallel cells increase charge capacity but do not multiply pack voltage.

Power-bank output is a different basis

A power bank may rate internal cells near 3.7 V but deliver USB at 5 V or higher through electronics. Output-equivalent mAh must account for output voltage and conversion loss; it is not the same label basis as internal-cell mAh.

Wh is safer for cross-voltage comparison

Two batteries can have the same mAh and very different energy when their voltages differ. Compare Wh when the goal is stored energy, then convert to mAh only for a specified voltage.

Truth boundary: this is an idealized nominal-voltage energy/charge model. Real battery voltage varies with chemistry, state of charge, temperature, age and load. Efficiency/output/runtime fields are scenarios, not a battery-health test or safety certification. Verify the label/datasheet and use qualified guidance where battery packs or high-energy electrical systems create safety consequences.

Wh to mAh conversion with the voltage assumption visible

Enter watt-hours and nominal voltage to calculate milliamp-hours, or reverse the relationship to solve Wh or voltage. Unit normalization supports mWh, Wh, kWh, mAh, Ah, mV and V without changing the governing equation.

Battery chemistry and pack voltage

Quick profiles cover common nominal cell values such as LiFePO₄, Li-ion/LiPo, high-voltage Li-ion, LTO, NiMH and lead-acid. Series-cell count multiplies nominal cell voltage; always verify the actual battery label or datasheet instead of assuming chemistry from appearance.

Compare the same energy at many voltages

The scenario table holds Wh constant across common battery/system voltages. It makes the central limitation of mAh comparisons visible: the same stored energy maps to a larger mAh number at lower voltage and a smaller mAh number at higher voltage.

Efficiency and output-equivalent capacity

The optional efficiency model estimates delivered energy and output-equivalent mAh at a selected output voltage. This is useful for reasoning about regulated outputs such as power banks, but it does not rewrite the battery manufacturer’s rated internal-cell mAh.

Local evidence and repeat use

Export a voltage scenario CSV or a Project JSON, save up to 12 explicit local conversions, and copy a settings-only link. No account or external calculation API is required.