Wh vs Ah, What is the difference between Wh and Ah?

Article update: The Difference in Watt-hours and Amp-hours


Today we will talk about the difference between Wh vs Ah, How many & How to convert? We know that the Lithium battery has several important parameters, namely the working Voltage (V), Ampere hour (Ah), and Watt hour (Wh), which we often see on laptop batteries. Usually, when we compare the size of the battery capacity, we tend to use Ampere hour (Ah) as the unit of comparison. Such as the battery in the mobile phone and the battery of the mobile power supply.

Watts and Amp Hours: How many & How to convert?
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Wh vs Ah, they are two different concepts

Ah represents the charge of the battery, and Wh represents how much work the battery can do.

For example, Ah can be regarded as the length of a river. A large value of Ah can only mean that the river is very long, but it does not mean that the river is very large. The size of a river depends not only on its length but also on its width. Multiplying the width (voltage) by Ah is the size of the river, That’s Wh

What is the relationship between Wh vs Ah?

I*t=Q and I represent current (A), t represents time, and Q represents the number of charges (Ah). For example: if a battery capacity is marked as 1000mAh, then when the working current is 100mA, it can theoretically supply power for 10 hours.

But there is no voltage involved here. If the voltage is added, the formula should be like this: U*I*t=U*Q=W. Among them, U represents the voltage, and W refers to the electric power, which indicates how much work the battery can do. The unit is expressed in Wh

Wh vs Ah are two different concepts, which cannot be generalized, and they can be converted into each other through formulas. When everyone understands it, it will be much easier when facing doubts about power.

Read more: About PV Power Calculation Formula

How to convert Wh to Ah?

1. The conversion method between Wh vs Ah is as follows:

  1. Watt hour = milliampere hour/1000×voltage, milliampere hour=watt hour/voltage*1000. As long as you know the rated working voltage and the capacity of the battery, you can convert it into Watt Hours. For example, for a 10000mAh mobile power supply, the standard voltage is 1.8V, then 10000mAh/1000×1.8=18Wh.
  2. Watt hour, the unit is Wh. Milliamp hours, the unit is mAh. These are two different units, they cannot be directly converted, and a formula is required.
  3. Watt hours are related to current, voltage, and time, and they are directly proportional. As an indicator of the battery, Ah is related to current and time and is proportional to them. Therefore, there is a relationship between watt hours and ampere hours.

2. Expansion:

Battery capacity:

  • The unit of battery capacity is usually expressed in Ampere hours, which refers to the amount of electricity released by the battery under certain conditions.
  • The classification of battery capacity can be classified according to three conditions: theoretical capacity, actual capacity, and rated capacity.

How to calculate power consumption in one hour?

How much electricity in one hour mainly depends on the power of an electrical appliance, because the calculation of power consumption is one hour of electricity per 1kw, so if we know that the power of an electrical appliance is 1kw, then one The power consumption per hour should be 1 kilowatt hour, and the power consumption of electrical appliances is directly proportional to the power of the electrical appliances.

The power consumption in one hour is Electrical power (kW) multiplied by the usage time of 1 hour, and the result is the power consumption of the electrical appliance in 1 hour.

In daily life, the power of different electrical equipment is different, but the power they consume in one hour is also different. The greater power of the appliance, the more power it consumes per hour, and the smaller power of the appliance, the Less power consumption per hour.

How to calculate the average hourly electricity consumption(convert Ah to Wh)?

1. Calculation formula: power consumption = power (w) * time (h) / 1000, the unit of the result is KWH.

2. Power affects consumption, an electrical appliance of one kilowatt, working for one hour, consumes 1000w/hour of electricity.

3. If the power of the TV is 300w, the power consumption for one hour is: 300w×1h/1000=0.3, that is, 0.3 kWh of electricity.

How to calculate the hourly electricity consumption?

The calculation method of electrical power consumption:

No matter what kind of electrical appliance, the power (watts, represented by the letter W) will be marked on the instruction manual or the nameplate. Usually, what we call the power consumption is how many kilowatt-hours of electricity. This can also be understood as the electricity that 1000 (W) electrical appliances consume in one hour.

The calculation method of electricity consumption:

Power consumption (kWh) = power (W) / 1000X time (hours)

For example, the power of the air conditioner is 1500W, and its power consumption for one hour is:


However, because the air conditioner will stop when it reaches the set temperature, this calculation is not accurate. The calculated power consumption is only accurate if the intermediate downtime is removed.

It is accurate to calculate the power consumption of the rice cooker, for example, the power consumption of a 750W rice cooker for half an hour:


Why is the battery capacity generally used as the unit of Ampere hour (Ah), and not watt hour (Wh)?

The battery capacity has been expressed in Ah for a long time, the inventor of electric current was a French physicist, he made outstanding achievements in the research of electromagnetic interaction and made contributions to mathematics and chemistry. The ampere, the international unit of electric current, is named after his surname. Ampere is a unit of current intensity, hour is a unit of time measurement, and the combination of the two is Ampere-hour.

Watt and watt-hour (Wh) are power calculation units, and the larger unit of watt-hour is kilowatt hour (kWh), which is often used as a unit of electrical energy measurement and has nothing to do with Ampere-hour.

Ah is the battery capacity unit, which is the combined symbol Ah of Ampere (A) and time (h). The ampere hour value (Ah) is an indicator reflecting the capacity of the storage battery. If the storage battery is discharged with a current of 1 ampere (A) for 1 hour, it means that its capacity is 1 ampere-hour (1ah=3600 coulomb).

The capacity unit of the battery is “ampere hour”, referred to as “Ah”. Its meaning is: After the battery is fully charged, it is discharged with a certain current value. After a certain period of time, the voltage drops to the specified final value. The total electricity released is called the capacity of the battery, which is expressed by current and time. That is, Q₁₅=If * tf, Q₁₅ in the formula is the capacity of the battery at a temperature of 15°C;

“If” is the battery discharge current (A);

“tf” is the battery discharge time (hours).

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