Free tool
Watt Hours to Amp Hours Calculator
Amp-hours are watt-hours divided by voltage. Without the pack voltage there is no conversion — and an AC load's watt-hours are not yet battery watt-hours.
Ah = Wh ÷ volts
Ah = Wh ÷ V. 2,400 Wh at 48 V is 50 Ah; the same energy at 12 V is 200 Ah. When the watt-hours are an AC load, divide by inverter efficiency first; then divide by depth of discharge to get the nameplate pack size that covers the draw.
The inverse is amp-hours to watt-hours. Runtime still needs the load's watts — see watts to kWh.
The energy
Enter 2.4 kWh as 2,400.
Nominal pack voltage — required. Wh alone never give Ah.
LiFePO₄ often ~80–100%; lead-acid often ~50%.
The answer
Amp-hours drawn from the pack
50.00 Ah
Ah = Wh ÷ V → 2,400.00 Wh ÷ 48.00 V
That is the amp-hour quantity removed from the battery for this energy. It is not yet a pack size.
Pack capacity at 80% DoD
62.50 Ah
Nameplate capacity needed so that using only 80% of it still covers the load: 50.00 Ah ÷ 0.80 = 62.50 Ah. At 100% DoD the two figures match.
What this does not tell you
Whether the inverter can start the load — surge current is a different limit. Charge rate or solar recharge time. A wired ampacity or breaker size on the DC bus. Confirm against the battery and inverter nameplates and the battery siting rules.
Informational use only, please verify before you rely on it
This reproduces the standard relationship Ah = Wh ÷ V, with optional depth-of-discharge and inverter-efficiency adjustments. It is a preparation aid, not a determination. It does not size conductors, overcurrent protection, inverters or charge equipment, and it does not decide whether a battery may be installed in a given location. Confirm against the equipment nameplates and applicable codes.
This tool is provided for general informational and educational purposes only. Its output is an illustrative estimate generated from the values you enter and from general assumptions that will not match every deal, market, lender, or homeowner. It is not tax, legal, accounting, financial, or professional advice, and it is not a quote, an offer, a credit decision, or a guarantee of pricing, approval, timing, savings, or eligibility.
You are solely responsible for independently confirming all information presented here including any figures, rates, fees, margins, timelines, tax treatment, and federal, state, local, or utility incentives, with the applicable lender, authority having jurisdiction, and your own qualified tax, legal, and financial advisors before acting on it, relying on it, or presenting it to a homeowner or any third party. Incentive programs, lender terms, and permitting requirements change frequently and vary by jurisdiction.
Seamless Home is not a tax advisor, law firm, lender, or licensed installing contractor, and makes no representation or warranty as to the accuracy, completeness, or currency of the information produced by this tool. To the fullest extent permitted by law, Seamless Home accepts no liability for any decision made or action taken in reliance on it.
Voltage is not optional
Battery marketing mixes Wh and Ah freely, which is fine inside one voltage family and misleading across them. A "100 Ah" 12 V pack holds about 1.2 kWh; a "100 Ah" 48 V pack holds about 4.8 kWh. Convert to watt-hours before comparing packs, and convert back only at the voltage you will actually wire. The home battery siting checker covers where that pack is allowed to live; home battery backup covers the accountability layer around the install.
Frequently Asked Questions
How do you convert watt-hours to amp-hours?+
Divide watt-hours by the battery voltage: Ah = Wh ÷ V. 2,400 Wh at 48 V is 50 Ah. Watt-hours alone never convert — without a voltage there is no amp-hour figure.
Why does voltage matter?+
Because amp-hours measure charge at a specific voltage. The same 2,400 Wh is 200 Ah on a 12 V bank and 50 Ah on a 48 V bank. Comparing Ah across different voltages without converting to Wh is comparing different quantities.
How does depth of discharge change the answer?+
Nameplate Ah assumes you could empty the pack. If you only plan to use 80% of it, you need 50 Ah ÷ 0.80 = 62.5 Ah of nameplate capacity to cover a 50 Ah draw. Lead-acid banks are often limited further; many LiFePO₄ packs allow deeper use — follow the manufacturer.
What if my watt-hours are an AC load?+
Divide by the inverter efficiency first. 2,400 Wh at the AC terminals through a 90% efficient inverter requires 2,667 Wh at the battery, which is 55.6 Ah at 48 V before depth of discharge is applied.
Is 100 Ah the same as 100 amp-hours on every battery?+
As a unit, yes — but only at the voltage the Ah figure was stated for, and only as a nameplate capacity. Usable energy still depends on depth of discharge, temperature and the rate of discharge.
How do I go the other way?+
Multiply amp-hours by voltage: Wh = Ah × V. The amp-hours to watt-hours calculator does that and can apply depth of discharge and inverter efficiency for a usable AC figure.
Is this a determination?+
No. It reproduces the standard relationship between watt-hours and amp-hours as a preparation aid. It does not size an inverter, a charge controller or the wiring, and it does not decide whether a battery may be installed in a given location. Confirm against the equipment nameplates and applicable codes.
Related resources
Amp Hours to Watt Hours Calculator
The inverse — nameplate and usable Wh, with optional inverter efficiency.
Learn more →Watts to kWh Calculator
Energy from a load's watts and runtime — what the battery has to cover.
Learn more →Home Battery Siting Checker
Where a home battery can and cannot be installed.
Learn more →Home Battery Backup
What a battery backup project has to get right beyond the kWh figure.
Learn more →Battery math that matches the install
Seamless Home coordinates home battery projects with clear scope and a single point of accountability. Coverage is confirmed per service area rather than promised as blanket availability.
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