The calculation, without hidden assumptions
Ah measures electric charge while Wh measures energy. Voltage is the bridge between them. Keeping both directions on one page makes the assumption obvious: a 100 Ah battery does not have one fixed Wh capacity unless its voltage is also known.
How to use this calculator
Choose Ah → Wh or Wh → Ah.
Enter the known capacity and the nominal or relevant battery voltage.
Read the converted capacity, secondary units and reverse check before using the result in a runtime estimate.
Where people use it
- •Battery and UPS capacity comparisons
- •Solar and portable-power planning
- •Checking manufacturer capacity labels
Example: 100 Ah at 12 V
100 Ah × 12 V = 1,200 Wh, or 1.2 kWh. The same 1,200 Wh divided by 12 V returns 100 Ah.
What the result does not assume
- •Nominal voltage is a simplified energy conversion basis. Real battery voltage changes with state of charge and load.
- •Wh capacity does not directly equal usable energy; battery chemistry, discharge limits and conversion losses matter.
Frequently asked questions
Can I convert Ah to Wh without voltage?+
No. Energy depends on both charge and voltage.
Is a 100 Ah 12 V battery the same as 100 Ah 24 V?+
No. The 24 V battery has twice the nominal watt-hour energy at the same Ah rating.
Does this predict runtime?+
No. Use the Battery Runtime Calculator to add load, depth-of-discharge and efficiency assumptions.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
Battery Runtime Calculator — Ah, Wh, DoD & Efficiency
Estimate battery runtime from amp-hours, voltage, load power, usable depth of discharge and system efficiency with all assumptions visible.
OpenElectricity Cost Calculator — kWh & Energy Cost
Estimate energy use in kWh and simple electricity cost from device watts, hours per day, number of days and your own tariff per kWh.
OpenVA to Watts Calculator — Apparent vs Real Power
Convert volt-amperes to watts or watts to VA using an explicit power factor, while keeping apparent power and real power separate instead of treating them as interchangeable.
OpenJoules ↔ Watt-Hours Calculator — J, kJ, MJ, Wh & kWh
Convert joules to watt-hours or watt-hours to joules using the exact 3,600 J per Wh relationship, with kJ, MJ, Wh and kWh equivalents plus visible reciprocal working.
OpenInternal Resistance Calculator — Battery Load Test, Two Points & Voltage Sag
Estimate a source or battery internal resistance from open-circuit and loaded voltage, from two load points, or run the internal-resistance model forward to check sag, loss and efficiency.
OpenOhm's Law Calculator — Volts, Amps, Ohms and Watts
Calculate voltage, current, resistance and power from any two positive electrical values using Ohm's Law and Watt's Law.
OpenReactance Calculator — Inductive XL, Capacitive XC & LC Resonance
Calculate inductive or capacitive reactance, reverse-solve frequency or component value, or find ideal LC resonant frequency with engineering-unit inputs and visible formulas.
OpenThree-Phase Power Calculator — kW, kVA, kVAR & Power Factor
Calculate balanced three-phase apparent, real and reactive power from line-to-line voltage, current and power factor, with phase angle shown for the simplified power triangle.
OpenMore in this calculator collection
Browse nearby calculators in the same topic cluster so related pages reinforce each other instead of sitting as isolated URLs.
Free publisher widget
Put this calculator on your website
Give readers the live calculator without rebuilding the math. Copy the responsive embed in one click, or customize width, height, border and corner radius before publishing. The branded MAXScanner attribution stays visible.
Calculator embed HTML
Paste this code into your page. Focus the code box to select it manually.
Keep the result connected to the real job
MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.