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AA & AAA Battery Life Calculator

Estimates how long AA, AAA, C, D or 9V cells will run a device from its average current draw.

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Enter your figures and press Calculate.
In short AA & AAA Battery Life Calculator is a free online tool on inputtesthub.com that estimates how long AA, AAA, C, D or 9V cells will run a device from its average current draw. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the AA & AAA Battery Life Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the AA & AAA Battery Life Calculator

The AA & AAA Battery Life Calculator estimates how long AA, AAA, C, D or 9V cells will run a device from its average current draw. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Working out how often a wall clock or remote needs new cells.
  • Comparing alkaline against rechargeable for a device.
  • Estimating battery cost per year for a gadget.

Details

AA alkaline≈ 2,500 mAh
AA NiMH≈ 2,000 mAh
9V PP3≈ 550 mAh
In seriesVoltage adds, capacity does not

The maths behind it

This tool uses Runtime = cell capacity ÷ average draw, multiplied by a usable fraction. Cells in series raise voltage; only cells in parallel add capacity. Every intermediate value is shown on screen, so the result can be checked by hand.

Four AA cells in a torch give 6 V for the same 2,500 mAh, not 10,000 mAh. Alkaline capacity is also load-dependent — a high-current device may extract barely half the rated figure, which is where NiMH does better despite its lower number.

Frequently asked questions

Does the AA & AAA Battery Life Calculator cost anything?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the utility.
Is the AA & AAA Battery Life Calculator safe to use with private information?
No. The AA & AAA Battery Life Calculator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
Can I check the maths myself?
It uses Runtime = cell capacity ÷ average draw, multiplied by a usable fraction. Cells in series raise voltage; only cells in parallel add capacity. The full working is printed under the result, so you can follow every step rather than trusting a black box.
When would I actually need the AA & AAA Battery Life Calculator?
In practice it gets used for three things: working out how often a wall clock or remote needs new cells. Comparing alkaline against rechargeable for a device. Estimating battery cost per year for a gadget. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there a catch?
Four AA cells in a torch give 6 V for the same 2,500 mAh, not 10,000 mAh. Alkaline capacity is also load-dependent — a high-current device may extract barely half the rated figure, which is where NiMH does better despite its lower number.
What figures does the AA & AAA Battery Life Calculator work from?
AA alkaline is ≈ 2,500 mAh. AA NiMH is ≈ 2,000 mAh. 9V PP3 is ≈ 550 mAh. These are printed on the page itself, so you do not have to take them on trust.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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