Amp-Hours To Watt-Hours (Ah To Wh): Calculator + Chart

To calculate watts-hours from amp-hours, we need to use the following formula:

Watt-hours = Amp-hours × Volts

As we can see, amp-hours multiplied by voltage equals watt-hours.

Using this equation, we can accurately convert watt-hours from amp-hours. Below the calculator, you can also check an Ah to Wh conversion chart for 120V and 220V circuits, and the battery amps hours chart for 12V and 24V batteries.

You can find the Ah to Wh calculator here:


We have also used the calculator to produce an amp-hour to watt-hour conversion chart for the most common Ah values (at 120V and 220V):

Ah To Wh Conversion Chart (120V And 220V)

Amp-Hours (Wh) Watt-Hours (at 120V): Watt-Hours (at 220V):
0.1 amp hour to watt hours: 12 Wh 22 Wh
0.2 amp hours to watt hours: 24 Wh 44 Wh
0.3 amp hours to watt hours: 36 Wh 66 Wh
0.4 amp hours to watt hours: 48 Wh 88 Wh
0.5 amp hours to watt hours: 60 Wh 110 Wh
1 amp hour to watt hours: 120 Wh 220 Wh
2 amp hours to watt hours: 240 Wh 440 Wh
5 amp hours to watt hours: 600 Wh 1100 Wh
10 amp hours to watt hours: 1200 Wh 2200 Wh
20 amp hours to watt hours: 2400 Wh 4400 Wh

Batteries run on 12V or 24V voltage. Here is the full battery amps hours chart:

Battery Amps Hours Chart

Battery Amp Hours (Ah) Battery Watt Hours (At 12V) Battery Watt Hours (At 24V)
100 mAh 1.2 Wh 2.4 Wh
1000 mAh or 1 Ah 12 Wh 24 Wh
2 Ah 24 Wh 48 Wh
3 Ah 36 Wh 72 Wh
4 Ah 48 Wh 96 Wh
5 Ah 60 Wh 120 Wh
10 Ah 120 Wh 240 Wh
20 Ah 240 Wh 480 Wh
30 Ah 360 Wh 720 Wh
40 Ah 480 Wh 960 Wh
50 Ah 600 Wh 1200 Wh
60 Ah 720 Wh 1440 Wh
70 Ah 840 Wh 1680 Wh
80 Ah 960 Wh 1920 Wh
90 Ah 1080 Wh 2160 Wh
100 Ah 1200 Wh 2400 Wh
120 Ah 1440 Wh 2880 Wh
140 Ah 1680 Wh 3360 Wh
160 Ah 1920 Wh 3840 Wh
180 Ah 2160 Wh 4320 Wh
200 Ah 2400 Wh 4800 Wh
250 Ah 3000 Wh 6000 Wh
300 Ah 3600 Wh 7200 Wh
350 Ah 4200 Wh 8400 Wh
400 Ah 4800 Wh 9600 Wh
450 Ah 5400 Wh 10800 Wh
500 Ah 6000 Wh 12000 Wh
600 Ah 7200 Wh 14400 Wh
700 Ah 8400 Wh 16800 Wh
800 Ah 9600 Wh 19200 Wh
900 Ah 10800 Wh 21600 Wh
1000 Ah 12000 Wh 24000 Wh
2000 Ah 24000 Wh 48000 Wh

Example: Let’s say you have a 100 Ah battery running on 12V. What is the battery capacity in Wh? You can just consult this battery amp hours chart and see that a 100 Ah battery has a 1200 Wh battery capacity.

Knowing how to convert Ah to Wh is quite a useful trick. We have an interesting article about how long will a 100Ah battery last here with a 400W appliance example. Once you convert amp-hours into watt-hours, the calculation becomes much much easier.

19 thoughts on “Amp-Hours To Watt-Hours (Ah To Wh): Calculator + Chart”

  1. I have a 300 amp hour LiFePo4 battery and the label on the side of the battery says that there are 3840 watt hours fully charged, I am guessing at 120V. In the chart above it says that 20 amp. hours equal 2400 watt hours at 120 V. If that is correct I don’t understnad why a 300 amp hour battery would not give 15 times that. (20 amp hours times 15 equals 300 amp hours) or 15 x 2400 watt hours, equalling 36,000 watt hours. Sorry for my confusion, please explain. Thanks, Jim

    • Hello Jim, here’s how you can figure this out: The 300 Ah battery contains 3,840 Wh when fully charged. That means that the voltage is 3,840Wh/300Ah = 12.8V. That’s a standard 12V battery voltage. You don’t have to guess the voltage, you can simply calculate it by dividing the watt-hours by amp-hours; the result is the voltage.

      When you reduce that guessed 120V to 12V, you get the results in the chart. Hope this helps.

  2. So here’s an example: If I have a 1.5kw solar panel, to 2 x 20 amp batteries – how long can I run a 300w heater (through a 220v inverter)?

    • Hello Neil, here’s how you go about figuring that out: 300W heater requires 300W every hour to run (so that’s 300Wh). Now, two 2×20 amp batteries (they are probably 12V batteries) can produce 40A*12V = 480W. That means that the 300W heater will run for 480W/300W = 1.6 hours just on batteries.

      If you can use the solar panels to continuously supply 1.5 kW of electricity to a 300W heater, it will easily run for as you as you’re capable to supply that power. Does this answer the question? Maybe you can specify a bit more and we can help you out further.

  3. Can someone help me with the calculations on this please. I have a 12V 41ah car battery. This goes to an alternator which then outputs 220v-240v to a device which uses 1500w. How long would this device last running off the fully charged battery?

    • Hello George, of course. First, you calculate the capacity of the battery in Wh; 12V*41Ah = 492 Wh. Now, this capacity can run a 492W device for 1 hour. If you have a 1,500W device, you do this calculation: 492Wh/1,500W = 0.328 h or about 20 minutes. This is how long a fully charged 12V 41Ah car battery can sustain 1,500W output. Hope this helps.

    • Hi George. I have a led acid 12v 200ah tubular battery. Running a embroidery mechine 300 watt how long can I run this mechine with this battery off an inverter

  4. Please help me I can’t until any of this. I bought a solar panel kit. Panels are 100wh each to two 12v/ 20AH batteries connected to a 600 wh solar inverter. I plugged a space heater into the inverter and it could not power but I was told this setup could power my travel trailer.

    • Hello Kathryn, space heaters usually run on 1,500W. The setup with 100W panels and 600Wh solar inverter might be a bit too small to run a 1,500W device. You could try running the heater on the lowest possible setting and see if that works.

    • I have a fordexpition 2002 comper and I was trying run a 840watts A/c but works for few minutes the than the battery gets low the alternator is charging good and the battery is good

  5. i just want my fridge to work for 12 hours a day..what do i need? how many solar panels, how big the inverter..what else i need..i have the in P.R…..please heeeelp…i cannot deal with all those numbers..just tell me what do i need to buy. thank you…

    • Hello Danielle, sadly there is no one-size-fits-all answer here. An average fridge runs from 1 kWh to 2 kWh per day. If you want to use it for 12 hours per day, it will require at most 1 kWh. If you are using 100W solar panels in a location with 5 peak hours, one such panel will generate 0.5 kWh per day. To run your fridge on 100W solar panels, you would need 2 of these smaller panels. 1 300W panel should do the job as well. Hope this helps.

  6. I have a backup power device with a capacity of 2016Wh 50.4v, if I plug a load of 6 Amps at 120v, for how long will it last?

    Thank you

    • Hello Hernan, alright, we have a backup capacity of 2,016 Wh, and 6A*120V = 720W load. Here is how you can calculate this: 2,016Wh/720W = 2.8h. Basically, your backup power device will last 2 hours and 48 minutes when powering a 720W device. Hope this helps.

  7. Ok It looks like I found a site that can help me…Sweet!
    I have (6) 2VDC (UPS DEEP CELL) 165 Ah batteries wired in series to a12vdc string.
    I have (4) of those 12vdc strings wired in series-parallel to 48vdc.
    is my capacity doubled
    My calcs say I have (4) 165ah battery strings to 48vdc. 4 x165= 640Ah.
    Is this correct?
    Below does not consider only 50% max depletion of batteries
    my run time for simplicity if at 640Ahs 10amps @ 48vdc= 64hours run time.
    Need help My Brain hurts…LOL

    • Hello Stan, the calculations are the theoretical estimates, yes. As you have correctly suggested, you have to factor in the losses that are specific to different batteries (lead batteries may have max depletion of 50%).


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