Milliamp Hours to Watt Hours (mAh to Wh) Conversion Calculator

Updated:

May 23, 2023

Watt-Hours Results:

mAh × V / 1000 =

0.00 Wh

Conversion formula: Wh = mAh × V / 1000

What Is Milliamp-Hours (mAh)?

Milliamp-hours is short for milliampere-hours. It is a unit that measures how much electric charge a power source will discharge over a one hour period at a specific voltage.

Milliamp-hours, sometimes written as mAh, is usually used as a measure of battery capacity. It gives a general idea of how long a battery will last/give off electric charge before it needs a recharge. For instance, a battery rated 5000 mAh would be expected to last longer than a 3800 mAh when used to power the same device.

What Is Watt-Hours (Wh)?

Watt-hours is a unit of energy (more times than not, electrical energy). It is a measure of how much energy is absorbed or discharged by an electrical device when the device produces or uses a certain amount of power over time.

In essence, one watt-hours is the amount of electrical energy produced when one watt of is power generated or used over one hour.

Like milliamp-hours, watt-hours may be used as a measure of battery capacity. However, in many cases, battery makers opt for milliamp-hours or amp-hours.

Why Convert Milliamp-Hours to Watt-Hours?

Converting milliamp-hours (mAh) to watt-hours (Wh) is useful when comparing the capacity of batteries, especially when the batteries have different voltages.

If we compare the mAh of batteries with different voltages directly, we’d only be comparing the amount of electric charge they give off over one hour. But such comparison may be limiting. If we want an encompassing comparison, we have to compare the batteries’ energy storage capacity.

For clarity, say we have two batteries A & B and A is rated 2000 mAh 5 volts while B is 2000 mAh 8 volts. Both batteries will discharge the same amount of electric charge (2000 mA) over one hour. However, battery B will store more energy than A since its Wh would be 16 Wh while that of A is 10 Wh.

How to Convert Milliamp-Hours to Watt-Hours (mAh to Wh)

mAh to Wh Conversion Formula

To derive the mAh to Wh conversion formula, we need the formula for electrical energy (Wh).

Electrical energy is a product of power and time. Going by that, we can represent it as:

electrical energy (Wh) = power (W) x time (h) (1)

Now, that we have the formula for electrical energy, we need the formula for power. With the formula for power, we’ll expand W into quantities that can show the relationship between Wh and mAh.

Power equals voltage multiplied by current (amperage). So, we can represent it as:

power (W) = voltage (v) x current (A) (2)

Now, we’ll substitute power for voltage x current into (1):

electrical energy (Wh) = voltage (v) x current (A) x time (h) (3)

(3) can be rewritten as:

Wh = v x Ah (4)

In (4), we have the formula for converting amp-hours (Ah) to watt-hours (Wh). But to get the formula to convert mAh to Wh, we need the formula to convert milliamp-hours to amp-hours.

Amp-hours equals the milliamp-hours divided by 1000:

Ah = mAh/1000 (5)

So, if we substitute Ah for mAh/1000 into (4), we’ll get the formula for an mAh to Wh conversion:

Wh = v x mAh/1000

Basically, to convert milliamp-hours (mAh) to watt-hours (Wh), we’ll multiply milliamp-hours times voltage then divide by 1000. Then to do the reverse – convert watt-hours to milliamp-hours – we’ll multiply watt-hours by 1000 then divide by voltage.

So, to convert Wh from mAh, enter voltage and mAh in their corresponding fields on our mAh to Wh calculator & mAh becomes Wh.

Conversion Examples

What’s the battery capacity of a 5000 mAh, 3 v average C battery in watt-hour?

To get this battery’s capacity in watt-hours, all we have to do is multiply 5000 milliamp-hours times 3 v then divide by 1000:

3 x 5000/1000

= 15 Wh

A 12 v battery has an amperage of 360 mA and an average battery life of 7 hours when it powers a solar flood light. What is the energy in watt-hours the flood light consumes?

To solve this, we’ll calculate the battery capacity in milliamp-hours (mAh) by multiplying the battery’s amperage by battery’s life:

360 x 7 = 2520 mAh

Next, we’ll calculate energy e in watt-hours (Wh) by multiplying milliamp-hours times voltage and dividing by 1000:

2520 x 12/1000 = 30.24 Wh

How much energy in watt-hours is stored in a power bank rated 30,000 mAh and 24 volts?

We can solve this by simply multiplying milliamp hours times volts before dividing by 1000:

30,000 x 24/1000 = 720 Wh

Milliamp Hours to Watt Hours Conversion Chart

As mentioned earlier, to convert to Wh from mAh, enter voltage in the given spaces on our mAh to Wh calculator & mAh becomes Wh. But what if a conversion calculator is not readily available?

When a milliamp-hours to watt-hours conversion calculator is not available, quick conversion charts like those below can come in handy:

For a 12v battery:

mAh	Wh
1000	12
2000	24
3000	36
4000	48
5000	60
6000	72
7000	84
8000	96
9000	108
10,000	120

For a 20v battery:

mAh	Wh
1000	20
2000	40
3000	60
4000	80
5000	100
6000	120
7000	140
8000	160
9000	180
10,000	200

For a 24v battery:

mAh	Wh
1000	24
2000	48
3000	72
4000	96
5000	120
6000	144
7000	168
8000	192
9000	216
10,000	240

The Difference Between Amp-Hours (Ah) and Milliamp-Hours (mAh)

Amp-hours and milliamp-hours are both units that represent battery capacity. They are typically used as a measure of how much electric charge a battery can store. Better still, they define how much electric charge a battery can discharge over one hour at a specific voltage.

While very similar, Ah and mAh differ in magnitude. While amp-hours (Ah) measures in units, milliamp-hours (mAh) measures in thousandths (1/1000). Basically, the values Ah represents are generally larger than those mAh represents.

Charles Noble

Here at Spheral Solar, I’m a hands-on solar power enthusiast, constantly exploring and experimenting with DIY solutions. I’m dedicated to sharing my discoveries, insights, and even the bumps I hit along the way, all in the pursuit of a more sustainable future.