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Amp Hour Calculator

Amp Hour Calculator

The calculator will calculate amp hours needed to drive a certain load.

Select :

I want to calculate:



Battery Capacity






Load Size

Load Duration

Temperature Adjustment :
Age Adjustment :


Table of Content

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How easy was it to use our calculator? Did you face any problem, tell us!

Make use of this free amp hour calculator that is specifically designed to calculate amp hours from watts that corresponds to the battery amp hour calculations.

So without wasting your precious time, let’s move down to the article below that will let you calculate Ah battery manually as well. Else, you can fasten your computations with the help of this battery capacity calculator.

What Is Amp Hour?

In the dictionary of electrical engineering science:

“One Amp Hour is the amount of charge flowing through battery in one single hour”

Our free battery amp hour calculator is specially designed for this purpose.

How to Calculate Amp Hours?

Battery Ah calculations are quite easy if you understand the following physical equations:

Now before we move further, let’s recall the Ohms law that states the product of current and voltage equivalent to that of the maximum power provided by the electrical circuit.

P = V*I


E = V * I * T (As Power multiplied by Time equals Energy)


E = V*Q (As current rate over time is equal to the charge flowing through battery)

The same equation is utilised by our amp hours calculator to calculate battery Ah.The ampere and the flow of current can be variable in an area. Measure the amperage in your area and then install electrical appliances. It can be cost saving to measure the electric utilization of each appliance by the electric cost calculator. This can save your overall electricity cost of the apartment.


Go through the example below that is intentionally resolved to make your concept more clearer. Stay focused!


Suppose you have just bought a battery of 20 V and the charge stored in it is approximately 20Wh. Then how to calculate battery amp hours in this case?


By using the formula, we can better do battery power calculations in terms of its amp hour as follows:

E = V*Q

E = 20*20

E = 400

The free battery Ah calculator also does the same computations but saving you a lot of time.

Amp Hour Running Chart:

The following chart has been arranged after recording the amp hours of various electrical devices operating for different time durations (1h, 2h, 4h, 8h). Let’s go through these!

Device Wattage

Ah Needed For 1h Run Time Ah Needed For 2h Run Time Ah Needed For 4h Run Time Ah Needed For 8h Run Time
10 Watt 0.83 Ah (830 mAh) 1.67 Ah 3.33 Ah

6.67 Ah

20 Watt

1.67 Ah 3.33 Ah 6.67 Ah 13.33 Ah
50 Watt 4.17 Ah 8.33 Ah 16.67 Ah

33.33 Ah

100 Watt

8.33 Ah 16.67 Ah 33.33 Ah 66.67 Ah
150 Watt 12.50 Ah 25.00 Ah 50.00 Ah

100.00 Ah

200 Watt

16.67 Ah 33.33 Ah 66.67 Ah 133.33 Ah
250 Watt 20.83 Ah 41.67 Ah 83.33 Ah

166.67 Ah

300 Watt

25.00 Ah 50.00 Ah 100.00 Ah 200.00 Ah
350 Watt 29.17 Ah 58.33 Ah 116.67 Ah

233.33 Ah

400 Watt

33.33 Ah 66.67 Ah 133.33 Ah 266.67 Ah
450 Watt 37.50 Ah 75.00 Ah 150.00 Ah

300.00 Ah

500 Watt

41.67 Ah 83.33 Ah 166.67 Ah 333.33 Ah
600 Watt 50.00 Ah 100.00 Ah 200.00 Ah

400.00 Ah

700 Watt

58.33 Ah 116.67 Ah 233.33 Ah 466.67 Ah
800 Watt 66.67 Ah 133.33 Ah 266.67 Ah

533.33 Ah

900 Watt

75.00 Ah 150.00 Ah 300.00 Ah 600.00 Ah
1,000 Watt 83.33 Ah 166.67 Ah 333.33 Ah

666.67 Ah

1,500 Watt

125.00 Ah 250.00 Ah 500.00 Ah 1,000.00 Ah
2,000 Watt 166.67 Ah 333.33 Ah 666.67 Ah

1,333.33 Ah

2,500 Watt

208.33 Ah 416.67 Ah 833.33 Ah 1,666.67 Ah
3,000 Watt 250.00 Ah 500.00 Ah 1,000.00 Ah

2,000.00 Ah

4,000 Watt

333.32 Ah 666.68 Ah 1,333.33 Ah 2,666.68 Ah
5,000 Watt 416.65 Ah 833.35 Ah 1,666.67 Ah

3,333.35 Ah

10,000 Watt

833.33 Ah 1,666.67 Ah 3,333.33 Ah

6,666.67 Ah

You can also let this battery amp hour calculator provide swift aid in cross verification of all the values in the table above. How does it sound to you?

How Amp Hour Calculator Works?

This battery capacity calculator requires some simple inputs in order to calculate the results. Let’s go through these!


Simple Mode:

  • From the first drop-down list, select the parameter you wish to calculate
  • After this, enter the required ones in their respective fields
  • Now tap the calculate button

Advanced Mode:

  • Enter the load size and load current in designated fields
  • You can also set the battery age and heat adjustments along with its type
  • After you are done with the stuff, it’s time to hit the calculate button


The free ah battery calculator provides the following reactions to your actions:

  • Calculate battery capacity, runtime to full capacity, and discharge current ratio
  • Also, the battery Ah calculator displays the amps of battery that would be enough to run your desired load


How long will a 100 amp hour battery last?

Well, it depends upon the appliance that is attached to the battery. Let us take an example here for your ease. If you attach a load of 10W, the battery will continue to supply voltage up to 120 hours. But if you attach a load of 2000W, the same battery would only be able to provide current for 36 minutes. Further for battery capacity calculations, we better suggest you utilise the amp hours calculator for this purpose.

How many Ah is a 12V car battery?

Such a battery has an amp range of about 50Ah that you could also verify by using this calculator.

How long can a 100Ah battery run a TV?

A 100Ah battery would be able to run a 32-inch LED TV for 30 minutes and 50-inch LED TV for up to 15 minutes.

Is a higher Ah battery better?

The higher the Ah of the battery, the higher the amount of the current it will deliver. On a general tone, a higher Ah battery would be capable of producing more CCA (Cold Cranking Amps).

How many Ah is a normal car battery?

A normal car battery can provide current within the range of 50 to 60 Ah per hour. For better calculations, you can confirm the ratings with our online amp hour calculator.

How many solar panels does it take to charge a 100Ah battery?

A 610 Wattage solar system would be sufficient to charge a 100Ah battery that is lithium based ionised. But remember that the rating is true only when there are peak sun hours running.

How many amps can a 12v battery supply?

A local 12v battery would produce 600 Amperes per hour that could be also verified by this battery calculator Ah.

Why are Ah batteries important?

The only reason behind the demand of Ah batteries is the amount of steady current provided by them with respect to the time.


Coming to the point directly, batteries are designed depending upon their wattage ranges. And this wattage or amperage ranges do let you know which is the best product you need to buy to run a specific load. This is why we have programmed this battery amp hour calculator so as to get an instant confirmation about the battery amps sufficient to run your desired appliance. Moreover, you can also utilise the electricity cost calculator to estimate the actual cost you are bearing against each electrical device being operated.


From the source of Wikipedia: Ampere hour, Use, Other measures of electric charge,

From the source of Khan Academy: Defining the standard electrical units, Electric current, Current direction

From the source of Lumen Learning: Current, Drift Velocity

From the source of Libretexts: Electric Current Current and Voltage Measurements in Circuits, Drift Speed