Wh = Ah x V. To convert amp hours to watt hours, multiply the amp hour (Ah) rating by the battery’s nominal voltage (V).
In this formula, Wh stands for watt hours, Ah for amp hours, and V for voltage. If your battery capacity is given in milliamp hours (mAh), divide by 1,000 to get Ah before using the formula. Always use the nominal voltage stated in the battery specification, not a rounded or assumed value.
How do I convert amp hours to watt hours for real battery specs?
To help buyers quickly check typical battery ratings, use the table below. Find your battery’s amp hour rating in the left column and voltage across the top row. Multiply to get watt hours (Wh).
| Ah | 12V | 24V | 48V | 51.2V | 96V | 192V |
|---|---|---|---|---|---|---|
| 10 | 120 | 240 | 480 | 512 | 960 | 1920 |
| 20 | 240 | 480 | 960 | 1024 | 1920 | 3840 |
| 50 | 600 | 1200 | 2400 | 2560 | 4800 | 9600 |
| 100 | 1200 | 2400 | 4800 | 5120 | 9600 | 19200 |
| 200 | 2400 | 4800 | 9600 | 10240 | 19200 | 38400 |
| 280 | 3360 | 6720 | 13440 | 14336 | 26880 | 53760 |
| 460 | 5520 | 11040 | 22080 | 23552 | 44160 | 88320 |
| 600 | 7200 | 14400 | 28800 | 30720 | 57600 | 115200 |
What are worked examples of Ah to Wh conversion?
Example 1: A 100Ah battery at 51.2V: Wh = 100 x 51.2 = 5,120Wh.
Example 2: A 200Ah battery at 48V: Wh = 200 x 48 = 9,600Wh.
Example 3: A 24V battery rated at 10,000mAh: First, convert mAh to Ah (10,000 ÷ 1,000 = 10Ah), then Wh = 10 x 24 = 240Wh.
What is the most common mistake in amp hours to watt hours conversion?
The most common mistake is using the wrong voltage or confusing mAh with Ah. For example, using 12V for a 51.2V battery underestimates actual energy by over 75%. Always confirm the nominal voltage in the specification and convert mAh to Ah before calculation. Ask suppliers: “What is the nominal voltage and is the Ah rating at that voltage?”
Why does amp hours to watt hours conversion matter in procurement?
Converting amp hours to watt hours is critical for comparing battery offers, calculating system runtime, and verifying supplier claims. Inaccurate conversion can result in undersized systems, unexpected costs, or non-compliance with project requirements. Careful buyers request both Ah and Wh at the specified voltage and confirm that quoted energy is usable after depth-of-discharge limits.
What should I verify in supplier battery specifications?
Check that the amp hour rating matches the voltage and that both are stated clearly. Ask: “Is the Ah rating at the nominal voltage, and what is the rated Wh at that voltage?” Request the test report or datasheet showing both figures. For large orders, require confirmation that the Wh value accounts for depth-of-discharge and actual usable energy.
Next action: Run the Wh = Ah x V calculation on your own battery specs, and email suppliers to confirm both values before ordering.
Frequently asked questions
Can I use amp hours to watt hours conversion for lithium and lead-acid batteries?
Yes, the formula Wh = Ah x V applies to both lithium and lead-acid batteries, but always use the correct nominal voltage for each chemistry.
What if my battery is rated in milliamp hours (mAh) instead of amp hours (Ah)?
Divide the mAh value by 1,000 to convert to Ah before using the formula. For example, 10,000mAh = 10Ah.
Does depth of discharge affect the watt hour calculation?
The Wh calculation gives total rated energy. Usable energy is lower and depends on the allowed depth of discharge (DoD). Ask suppliers for usable Wh at your required DoD.
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