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Battery Ah to kWh converter

Battery capacity is sold in amp-hours (Ah), but solar energy is measured in kilowatt-hours (kWh). Enter your battery's Ah and voltage to convert between them — and see how much of that energy you can actually use.

Amp-hours from the battery label or spec sheet.
Nominal voltage — usually 12, 24, or 48 V.
How much you safely use — ~50% lead-acid, ~80–90% lithium.
0 total energy (Wh)
0 total energy (kWh)
0 usable energy (kWh)
0 usable capacity (Ah)

kWh = Ah × volts ÷ 1000. Usable energy = total energy × depth of discharge. Don't plan to use 100% of a battery — draining it fully shortens its life.

How amp-hours convert to kilowatt-hours Amp-hours multiplied by voltage gives watt-hours, divided by 1000 gives kilowatt-hours, and multiplied by the depth of discharge gives the usable energy. What you enter Capacity amp-hours (Ah) Voltage volts (V) Ah × V ÷ 1000 = kWh total stored energy × depth of discharge = usable kWh the energy you can really use
Amp-hours become kilowatt-hours through voltage — then depth of discharge sets what's usable.

How usable energy changes with depth of discharge

This curve updates with your inputs. It shows how much of your battery's energy is usable as you allow a deeper discharge — the marker shows your chosen depth of discharge.

Usable energy rises with the depth of discharge you allow.

Batteries are rated in amp-hours, but everything else in a solar system — your daily use, your panel output, your bill — is in kilowatt-hours. Converting between them is simple once you bring voltage into the picture, and it's the step that lets you compare a battery to your actual energy needs.

The conversion

Amp-hours only tell you half the story; you also need the voltage. Multiply them to get watt-hours, then divide by 1000 for kilowatt-hours: kWh = Ah × V ÷ 1000. A 200 Ah battery at 12 V holds 200 × 12 = 2400 Wh, or 2.4 kWh. The same 200 Ah at 48 V holds four times as much — 9.6 kWh — which is exactly why larger systems use higher battery voltages.

Why usable capacity is less than the label

You can't safely use all of a battery's rated capacity. Depth of discharge (DoD) is the fraction you can draw before recharging: around 50% for lead-acid and 80–90% for lithium. Draining deeper than that repeatedly shortens the battery's life. So usable energy is the total times the DoD — a 2.4 kWh battery at 80% DoD gives about 1.9 kWh you can actually count on.

Putting it to use

Once your battery is in kWh, you can match it to your daily energy use and see how long it will last. To size a battery bank for your loads, use the battery calculator; to see how long a bank will run a given load, the battery runtime calculator; and for a full off-grid design, the off-grid system wizard.

Related tools

Pair this with the battery calculator, the battery runtime calculator, and the energy production calculator to see how your panels, battery, and daily use fit together.

Frequently asked questions

How do I convert amp hours (Ah) to kilowatt hours (kWh)?

Multiply amp-hours by voltage for watt-hours, then divide by 1000: kWh = Ah × V ÷ 1000. A 200 Ah, 12 V battery is 2400 Wh = 2.4 kWh.

What is usable battery capacity and depth of discharge?

Depth of discharge is the share you can safely use — ~50% for lead-acid, 80–90% for lithium. Usable capacity is total capacity × DoD; going deeper shortens battery life.

How many kWh is a 200Ah 12V battery?

2.4 kWh total (200 × 12 ÷ 1000). At 80% depth of discharge, about 1.9 kWh is usable.