How to calculate kWh from Ah? In many cases (batteries, for example), we need to convert amp-hours (Ah) to kilowatt-hours (kWh). This is useful for car batteries, for example. With smaller 2500 mAh AA and 1000 mAh AAA batteries, we need to convert mAh to kWh (we’ll show you how to do that as well).
Further on you will find an Ah to kWh calculator; you just plug in Ah, voltage, and you’ll get kWh. Here’s a screenshot that illustrates how the Ah to kWh convert works (100 Ah 12-volt battery example):
To help you out, we have also calculated the Ah to kWh table (and mAh to kWh table) where you can see how many kWh is a 1 – 500 Ah at 12V. We have also used several examples to illustrate how you can use the Ah to kWh converter to figure out how many kWh can your battery provide.
First, however, let’s define what both of these electrical units are so we know what we’re talking about:
What Is Amp Hour? What Does Ah Mean On A Battery?
All batteries will have ‘Ah’ listed on the specification sheet. For example, the most common bigger battery is a 100 Ah car battery. To understand what does an Ah to kWh conversion actually means, we need to understand this key thing:
What is amp hour?
Amp-hour or ampere-hour is a unit of electric current, multiplied by hours. In essence, it tells us the capacity of a battery; that is, how big a battery actually is or how much juice the battery has.
1 amp hour battery will produce an electrical current of 1 amp for 1 hour (at specified voltage; usually 12V for batteries).
Here are some more examples that illustrate what amp-hours mean:
- 100 Ah is equal to 100A running for 1h, 20A running for 5h, or 1A running for 100h.
- 50 Ah is equal to 50A running for 1h, 20A running for 2.5h, or 1A running for 50h.
- 2500 mAh AAA battery will run at 2.5A for 1 hours, at 1000 mA for 2.5 hours, or at 100 mAh for 25 hours.
- 1000 mAh AAA battery will run at 1000 mA for 1 hours, or at 100 mAh for 10 hours.
The difference between mAh and Ah (milliamp-hours and amp-hours) is simply that 1Ah is equal to 1000 mAh.
What Is kWh?
kWh or kilowatt-hour is a unit of energy, multiplied by hours. A 1,000W electrical appliance running for 1 hour, will spend 1 kWh of electricity. The average US price for 1 kWh is $0.1319.
What’s the difference between Ah and kWh?
Both are units connected with time (hours), but Ah is a measure of electrical current (amps) and kWh is a unit of energy (kilowatts).
To convert Ah to kWh, you need to take voltage into account. That’s because voltage (volts) can convert amps into watts according to this basic electric power equation:
P (watts) = I (amps) × V (volts)
That means that 1 amp at 12V will generate 12 watts of power. It also means that 1 amp-hour at 12V will generate 12 Wh worth of electricity.
This is the key equation we can use to convert Ah to kWh (and mAh to kWh). Further on, we will solve an example for a small AAA battery and for a big 100 Ah battery.
Ah To kWh Calculator
To convert amp-hours to kWh, just input Ah (usually specified on the battery) and voltage (also specified on the battery; usually 12V). This calculator will dynamically calculate the kWh from input Ah and voltage:
You can find a similar calculator that converts kWh to Ah here.
Ah To kWh Table (Calculated kWh For 1-500 Ah 12V Batteries)
We can use the calculator above to calculate how many kilowatts do different size 12V batteries (with different Ah and mAh capacities) have. On top of that, we also specify how long will such a battery theoretically (without the voltage drop) last if it has a 1 amp current output:
| 12V Battery Size (in Ah): | Kilowatts (in kWh): | Running Hours At 1 Amp Output: |
| 1000 mAh (AAA battery) | 0,01 kWh | 1 hour |
| 2500 mAh (AA battery) | 0,025 kWh | 2.5 hours |
| 1 Ah | 0,01 kWh | 1 hour |
| 10 Ah | 0,12 kWh | 10 hours |
| 20 Ah | 0,24 kWh | 20 hours |
| 30 Ah | 0,36 kWh | 30 hours |
| 40 Ah | 0,48 kWh | 40 hours |
| 50 Ah | 0,60 kWh | 50 hours |
| 60 Ah | 0,72 kWh | 60 hours |
| 70 Ah | 0,84 kWh | 70 hours |
| 80 Ah | 0,96 kWh | 80 hours |
| 90 Ah | 1,08 kWh | 90 hours |
| 100 Ah | 1,20 kWh | 100 hours |
| 150 Ah | 1,80 kWh | 150 hours |
| 200 Ah | 2,40 kWh | 200 hours |
| 300 Ah | 3,60 kWh | 300 hours |
| 400 Ah | 4,80 kWh | 400 hours |
| 500 Ah | 6,00 kWh | 500 hours |
For example, a 50 Ah 12V battery has a 0,60 kWh capacity.
If we turn this around and ask ourselves what size 12V battery do I need for 1 kWh, we can calculate that as well using the electric power equation:
P (watts) = I (amps) × V (volts)
We just express the I (amps) like this:
I (amps) = P (watts) / V (volts)
1 kWh is equal to 1000 Wh; we just insert 1000 watts like this:
I (amps) = 1000W / 12V = 83.33 A
That means that we need an 83.33 Ah 12 battery for 1 kWh.
Hope this helps a bit. If you haven’t got an answer, you can use the comments below to pose a question and we’ll try to help you out with your Ah to kWh conversion.
There’s a little confusion in your explanations:
“kWh or kilowatt-hour is a unit of energy, multiplied by hours.”
The part before the comma is right, but the part after it throws a wrench in the works. A kilowatt is a unit of power. Multiplying kW by hours makes kWh, a unit of energy.
“What’s the difference between Ah and kWh?
Both are units connected with time (hours), but Ah is a measure of electrical current (amps) and kWh is a unit of energy (kilowatts).”
Your terminology’s loose again. Ah is a measure not of current but of electrical ENERGY (amperes times time). Amps are indeed a measure of current. kWh is indeed a unit of energy, but it it isn’t (kilowatts); it’s kilowatt hours.
Hello Jim, you are correct, we’ll try to correct this.
hi. i am trying to work out 0.2 kwh/24hrs to amp hrs. i have a 170ah battery and looking at 12v fridges, some say 0.52Ahr and another is saying 0.2kwh/24hrs. any help would be very much Appreciated. kind Regards
Hello Craig, if you run a fridge that uses 0.2 kWh per hour for 24 hours, you use 4.8 kWh. A 170Ah 12V battery holds 2,040 Wh. If you run such a fridge with this battery, you would need 4,800 Wh to run it for 24h. 2,040 Wh battery you have will run it for a little bit over 10 hours. Hope this calculation helps.
Another option is to use a power generator. You can check here what size generator you need to run a refrigerator and freezer.
You state, incorrectly, that 1AH @ 12V = 12kWh. It equals 12Wh. That’s a very important k to be throwing around, please fix this.
Hello John, thank you for noticing the mistake. It was a typo; it’s corrected now.
How many what’s do I use for 15 hours with my 100ah 24v lithium ion battery
Hello Tatenda, a 100Ah 24V battery has a capacity of 2400Wh. Here’s how you can calculate what wattage device you can run for 15 hours with this battery: 2400Wh / 15h = 160W. In short, you can run a device with a maximum wattage of 160W.
I have 200Ah 12v lithium battery. The total appliances in the house is 800 Watts. How many hours in total would I get from the battery. Thanks
Hello Ola, a 200Ah 12V battery has capacity of 200Ah × 12V = 2,400Wh. If we presume 100% discharge, this battery has enough juice to run 800W appliances for 3 hours.
Hi Bro I have 4 liquid batteries of 12 volt And 195Ah my Question is that if I use 1000watts per hour how time it will last notice( I have installed it with inverter 6kva in series for 48 Volts
Hi there, one 12V 195Ah has a capacity of 2340 Wh. It can run a 1000W unit for 2.34 hours. So, 4 of them could run the 1000W for a bit more than 9 hours.
I have batteries with varying ah, how many kW does it take to charge 1 ah. The machinery is 40v.
Hi Lyndon, alright most batteries are 12V. That means that 1Ah is equal to 12Wh. 1 kWh of electricity, for example, is thus equal to 83.3 Ah. Hope this helps a bit.
Because the majority of home owner is not “electrical boffins” they are led to believe that they need a massive eg 10 kWh installation.
The average household uses less than 50% of the capacity and intermittently.
Average specified availability for a town house is 3,5 kWA
Why do solar companies suggest such a large installation?
Hi Joseph, maybe it’s just this relationship: bigger unit = higher price? Profit motive, basically.