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Coulombs to Ampere-hours Converter

Convert coulomb to ampere-hour instantly. 1 C = 0.0002777777778 Ah, worked steps and a full reference table.

Formula
Ah = C × 0.0002777777778

How to use it

  • Type the value in coulomb — the result updates as you type.
  • Use Swap to flip the direction, or change either dropdown to convert between any two units.
  • Click the result to copy it. The URL updates too, so you can bookmark or share the exact conversion.

Examples

1 C0.0002777777778 Ah
5 C0.001388888889 Ah
10 C0.002777777778 Ah
100 C0.02777777778 Ah

One coulomb equals 0.00027777778 ampere-hours (Ah). To convert coulombs to ampere-hours, multiply by 0.00027777778; to go back the other way, multiply by 3600 instead.

The converter above does it as you type and shows the working underneath, so you can check the arithmetic rather than take the number on trust.

What coulombs and ampere-hours actually measure

Coulomb (C) — The coulomb is the SI unit of charge — one amp flowing for one second. Physics and electrical theory.

Ampere-hour (Ah) — An amp-hour is one amp sustained for an hour — 3,600 coulombs. Car and deep-cycle battery capacity.

Coulombs to Ampere-hours conversion table

The most common values, worked out in advance. Anything not listed can be typed straight into the converter.

CAh
1 C0.00027777778 Ah
2 C0.00055555556 Ah
5 C0.0013888889 Ah
10 C0.0027777778 Ah
25 C0.0069444444 Ah
50 C0.013888889 Ah
100 C0.027777778 Ah

How to convert coulombs to ampere-hours by hand

Multiply the number of coulombs by 0.00027777778.

For example, 25 C × 0.00027777778 = 0.0069444444 Ah.

Going the other way, divide by 0.00027777778 — or multiply by 3600, which is the same thing and easier to do in your head.

Everything runs in your browser

There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.

Questions people ask

How many Ah are in 1 C?

1 C equals exactly 0.0002777777778 Ah. Multiply any value in coulomb by 0.0002777777778 to get ampere-hour.

Is anything uploaded to a server?

No. The whole calculation happens in your browser. Nothing is sent anywhere, and the page keeps working offline once loaded.

Runs entirely in your browser. Nothing you type is uploaded, logged or shared.

Last updated 18 August 2026