# Volts to Watts (V to W) Conversion Calculator

Use our interactive calculator to easily convert volts to watts (V to W).

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watts
Conversion formula: watts = volts × amps

## Volts to Watts Conversion Charts

Here are some tables converting common AC and DC voltages to watts at various levels of current.

## How to Convert Volts to Watts (V to W)

Converting volts to watts is easy — you just need to know the current in amps. To convert volts to watts, simply multiply volts times amps.

Formula: watts = volts × amps

Abbreviated: W = V × A

Occasionally, you may also see watts abbreviated as P instead of W and amps abbreviated as I instead of A. The conversion formula remains the same.

Alternate abbreviation: P = V × I

### Example

Here's a simple example illustrating how to convert volts to watts.

Let's assume you own the following solar panel that is rated at 18.6 volts and 5.38 amps.

To calculate the watts produced by the panel in full sun, you would multiply volts times amps.

`18.6 volts × 5.38 amps = 100.07 watts`

It turns out your panel is a 100 watt solar panel.

### Why Convert Volts to Watts?

Knowing a device's wattage is necessary for estimating how much power it's using at a given moment, as well as how much energy it consumes overall.

For example, let's say you have this portable 12 volt fridge.

You look at its product specifications and see that it has a max current of 5 amps. To estimate its max power consumption in watts, you multiply its voltage by its amperage.

`12 V × 5 A = 60 W`

So, in this example, your 12 volt fridge uses a max of 60 watts.

It's important to know that the current rating listed on a device is usually its max current rating. In other words, the device may not be always using that much current. Fridges, for instance, enter a cooling cycle when the internal temperature gets too high. During a cooling cycle, a fridge is using much more energy than when it's simply insulating.

Knowing the wattage of your devices helps you do three main things when it comes to DIY solar power:

1. Size an inverter
2. Estimate energy usage
3. Size a battery bank

#### 1. Sizing an Inverter

Inverters are rated in watts. If you know the wattage of all your devices, you can sum them together to get your system's total power draw. This is the total watts being used if all your devices were running at peak power simultaneously.

For instance, let's say you plan to run a 200 watt fridge and a 75 watt fan off your inverter. You'd find your system's max power draw by summing the wattage of these two devices.

`200 W + 75 W = 275 W`

Your inverter needs to have a watt rating higher than this total. So a 250 watt inverter would be insufficient, but a 500 watt inverter would work.

#### 2. Estimating Energy Usage

Power is rated in watts, but energy is rated in watt hours or kilowatt hours. To estimate energy usage of your house or DIY electrical system, you need to convert watts to watt hours (or watts to kilowatt hours).

To do so, you need to know the wattage of all your devices as well as how many hours per day each one will run on average.

If you have a 75 watt TV that runs for 2 hours each day, for instance, you can estimate its watt hours (Wh) by multiplying watts by hours.

`75 W × 2 hrs = 150 Wh`

#### 3. Sizing a Battery Bank

The amount of energy a battery stores can also be expressed in watt hours or kilowatt hours. (Though often it is expressed in amp hours, which must be converted to watt hours or kilowatt hours.) So, if you know your estimated energy usage, you can use that number to size your battery bank.

For example, let's say you're designing a small off-grid solar power system. All together, you expect your devices to consume 200 watt hours per day. You want your battery to last for up to 3 days without recharging, so you could size your battery bank by multiplying the two numbers together to get the total energy usage of your system over the course of 3 days.

`200 Wh/day × 3 days = 600 Wh`

In this simplified example, your battery bank needs to have a capacity of at least 600 watt hours to meet your energy requirements.

## How to Convert Watts to Volts (W to V)

To convert watts to volts, divide watts by amps.

Formula: volts = watts ÷ amps

Abbreviated: V = W ÷ A

Alternate abbreviation: V = P ÷ I

### Example

For example, let's say you have a 300 watt solar panel that is also rated at 12.5 amps. You want the panel's voltage. Simply divide watts by amps to get volts.

`300 watts ÷ 12.5 amps = 24 volts`

Turns out your panel is a 24 volt solar panel.

## How to Convert Amps to Watts (A to W)

To convert amps to watts, multiply amps times volts.

Formula: watts = amps × volts

Abbreviated: W = A × V

Alternate abbreviation: P = I × V

### Example

Let's say you have a portable travel oven you want to use while on a road trip in your campervan. The oven is rated at 12 volts and 10.8 amps.

You calculate the maximum watts used by the oven by multiplying amps times volts.

`10.8 amps × 12 volts  = 129.6 watts` 