How do I convert Ah to Wh?

Multiply amp-hours (Ah) by the battery voltage. A 100Ah 12V battery stores 1,200 Wh (1.2 kWh). A 100Ah 24V battery stores 2,400 Wh (2.4 kWh).

How many Wh is a 100Ah 12V battery?

A 100Ah 12V battery stores 1,200 Wh (1.2 kWh) total. With LiFePO4 chemistry at 80% depth of discharge, the usable capacity is 960 Wh. With lead acid at 50% DoD, usable capacity is 600 Wh.

What is the difference between Ah and Wh for solar batteries?

Amp-hours (Ah) describe charge capacity at a specific voltage. Watt-hours (Wh) describe energy content regardless of voltage. Use Wh to compare batteries at different voltages — a 200Ah 12V battery and a 100Ah 24V battery both store 2,400 Wh.

Battery Wh Calculator

Convert amp-hours (Ah) to watt-hours (Wh) and kWh. Compare capacity across 12V, 24V, and 48V systems.

Battery specifications

Battery capacity?

Battery voltage?

Battery energy content

1,200 Wh (1.20 kWh)

Watt-hours1,200 Wh

Kilowatt-hours1.200 kWh

Usable (LiFePO4, 80% DoD)0.96 kWh

Usable (lead acid, 50% DoD)0.60 kWh

Equivalent Ah at 12V100.0 Ah

Equivalent Ah at 24V50.0 Ah

Equivalent Ah at 48V25.0 Ah

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How to Use This Calculator

Enter your battery's amp-hour (Ah) capacity and nominal voltage. The calculator instantly converts to watt-hours (Wh) and kilowatt-hours (kWh), and shows the equivalent capacity at 12V, 24V, and 48V — useful when comparing batteries across different system voltages.

Finding your battery's Ah and voltage

Both values are printed on the battery label. A common 12V lithium battery might say "12V 100Ah." A 48V LiFePO4 pack might say "48V 50Ah." The formula is always the same: Wh = Ah × V.

Usable capacity

The calculator also shows usable capacity — the energy you can actually extract without damaging the battery. Lead-acid batteries are limited to 50% depth of discharge (DoD). LiFePO4 (lithium iron phosphate) batteries allow 80% DoD, making them the preferred choice for solar systems.

The Formula

Wh = Ah × V kWh = Wh ÷ 1000 Usable Wh (LiFePO4) = Wh × 0.80 Usable Wh (lead acid) = Wh × 0.50 Equivalent Ah at 12V = Wh ÷ 12 Equivalent Ah at 24V = Wh ÷ 24 Equivalent Ah at 48V = Wh ÷ 48

The equivalent Ah at different voltages helps when comparing battery banks. A 200Ah 12V bank and a 100Ah 24V bank both store 2,400Wh — but the 24V system uses half the current, reducing wire heat loss and allowing thinner cables.

Example

RV with two 12V 200Ah LiFePO4 batteries in series (24V system)

Battery voltage24V

Capacity200Ah

Total Wh4,800 Wh

Total kWh4.8 kWh

Usable (LiFePO4, 80% DoD)3.84 kWh

Equivalent at 12V400Ah

Equivalent at 48V100Ah

This 24V system running 1,500Wh/day can power the RV for about 2.6 days without recharging. Adding two 200W solar panels provides roughly 1,700Wh/day in good sun — covering daily usage and keeping the batteries topped up.

FAQ

What is the difference between Ah and Wh? ▼

Amp-hours (Ah) measure electric charge — how many amps a battery can deliver for one hour. Watt-hours (Wh) measure energy — the actual work a battery can do. To convert: multiply Ah by voltage. A 100Ah battery at 12V stores 1,200Wh. The same 100Ah capacity at 24V stores 2,400Wh. Always use Wh when comparing batteries at different voltages.

Why does voltage matter for battery storage? ▼

Higher voltage systems store more energy per amp-hour and operate at lower currents for the same power output. This means thinner, cheaper wiring, less heat loss, and more efficient inverters. A 48V system delivering 3,000W draws only 62.5A, while a 12V system delivering the same power draws 250A — requiring massive cables and heavy busbars.

LiFePO4 vs lead acid — which is better for solar? ▼

LiFePO4 is the clear winner for solar storage: 3-5× more cycle life (3,000-6,000 cycles vs 300-500 for lead acid), 80% usable capacity vs 50%, faster charge acceptance, and no maintenance. The upfront cost is 2-3× higher, but the total cost over 10 years is typically lower. Lead acid still makes sense for seasonal or backup use where you won't cycle it daily.

How do I build a 24V or 48V battery bank from 12V batteries? ▼

Connect batteries in series to increase voltage. Two 12V batteries connected + to - in series = 24V. Four 12V batteries in series = 48V. The Ah capacity stays the same as a single battery. To add more Ah, connect identical strings in parallel. Always use identical batteries (same age, brand, and state of charge) when building battery banks.