Watts to Amps Calculator: Formula, Examples & Conversion Table
Converting watts to amps is useful when you need to understand how much current a device, appliance, inverter, battery system, or solar setup may draw. Watts measure electrical power, while amps measure electrical current. To calculate amps from watts, you also need voltage.
Basic watts to amps formula
Amps = Watts ÷ Volts
Use this formula when you know power and voltage and want to find current.
This guide explains the watts to amps conversion formula, shows practical examples, and includes a watts to amps calculator for batteries, solar systems, inverters, RVs, and household appliances.
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Watts to Amps Conversion Table for Typical Voltages
Use the table below for quick estimates at common DC and AC voltages. These values assume a power factor of 1.
Quick Conversion Table for 12V, 24V, 48V and 120V
| Watts | Amps at 12V DC | Amps at 24V DC | Amps at 48V DC | Amps at 120V AC |
|---|---|---|---|---|
| 60W | 5A | 2.5A | 1.25A | 0.5A |
| 100W | 8.33A | 4.17A | 2.08A | 0.83A |
| 300W | 25A | 12.5A | 6.25A | 2.5A |
| 600W | 50A | 25A | 12.5A | 5A |
| 1,000W | 83.3A | 41.7A | 20.8A | 8.3A |
| 1,500W | 125A | 62.5A | 31.3A | 12.5A |
| 2,000W | 166.7A | 83.3A | 41.7A | 16.7A |
This table shows why voltage matters. A 1,000 watt load draws about 83.3 amps at 12V, but only about 8.3 amps at 120V.
What Are Watts, Amps and Volts?
Before using a watts to amps calculator, it helps to understand what each electrical term means. Watts, amps, and volts describe different parts of an electrical system.
What Is a Watt?
A watt measures electrical power. It shows how much power a device uses or produces at a specific moment. Appliances, solar panels, inverters, and generators are commonly rated in watts.
For example, a 100W light uses much less power than a 1,500W space heater. Watts help you compare the power demand of different devices.
For a full explanation of watts, power ratings, and energy use, see our guide on What Are Watts and Why Do They Matter?
What Is an Amp?
An amp, short for ampere, measures electrical current. Current is the amount of electricity flowing through a circuit. Amps are important when choosing wires, fuses, breakers, charge controllers, and inverter cables.
Higher amps mean more current is flowing. In low voltage battery systems, large wattage loads can require very high current.
What Is a Volt?
A volt measures electrical pressure. Voltage pushes current through a circuit. Common battery systems include 12V, 24V, and 48V. Standard household outlets in the United States are commonly 120V.
Voltage is required for every watts to amps conversion because the same wattage can draw different current at different voltages.
If you want a clearer explanation of how voltage and current work together, see our guide on volts vs amps. It explains the real difference between voltage and current in simple terms.
Watts to Amps Formula
The standard watts to amps formula is simple. Divide watts by volts to get amps.
Watts to amps formula
Amps = Watts ÷ Volts
This formula works for most simple DC calculations and basic estimates.
For AC devices, especially motors and compressors, power factor may also affect the current calculation.
DC Watts to Amps Formula
For DC systems, such as batteries, solar setups, RV power systems, and marine electronics, the formula is direct.
DC watts to amps formula
A = W ÷ V
Use this formula for batteries, RV systems, solar setups, and most low voltage DC circuits.
Example:
240W ÷ 12V = 20A
A 240 watt load on a 12V battery system draws about 20 amps.
AC Watts to Amps Formula
For AC power, the formula may include power factor.
AC watts to amps formula
Amps = Watts ÷ (Volts × Power Factor)
Use this formula for AC motors, pumps, compressors, and other loads where power factor matters.
If the power factor is not available, a basic watts to amps calculator can still give a useful estimate, but the real current may be different.
If you want a clearer explanation of the diferences of DC and AC see our guide on DC V.S AC?.
Practical Watts to Amps Examples
The easiest way to understand watts to amps conversion is to compare common loads at different voltages. The formula stays simple, but the result changes with voltage.
100 Watts to Amps at 12 Volts
Formula: Amps = Watts ÷ Volts
Calculation: 100W ÷ 12V = 8.33A
So, 100 watts at 12 volts equals about 8.33 amps. This is common for small DC loads, portable power systems, and battery powered devices.
300 Watts to Amps at 12 Volts
Formula: Amps = Watts ÷ Volts
Calculation: 300W ÷ 12V = 25A
So, 300 watts at 12 volts equals about 25 amps. This current level matters when sizing wiring, fuses, and battery output.
1,000 Watts to Amps at 12 Volts
Formula: Amps = Watts ÷ Volts
Calculation: 1,000W ÷ 12V = 83.3A
So, 1,000 watts at 12 volts equals about 83.3 amps before efficiency loss. Large loads on 12V systems can require very high current.
1,000 Watts to Amps at 120 Volts
Formula: Amps = Watts ÷ Volts
Calculation: 1,000W ÷ 120V = 8.33A
So, 1,000 watts at 120 volts equals about 8.33 amps. This is why household AC loads draw much less current than the same wattage load on a 12V battery system.
How to Convert Watts to Amps
To convert watts to amps, you only need two numbers: power and voltage. Once you have them, divide watts by volts.
Step 1: Find the Watts
Look for the watt rating on the device label, appliance manual, inverter display, solar panel label, or product specification sheet. It may be shown as W or watts.
For example, if a device label says 600W, the power is 600 watts.
Step 2: Find the Voltage
Next, identify the voltage of the system. Battery systems are commonly 12V, 24V, or 48V. Household appliances in the United States commonly use 120V AC.
For example, if a device runs on a 12V battery, the voltage is 12 volts.
Step 3: Divide Watts by Volts
Conversion formula
Amps = Watts ÷ Volts
Divide the watt value by the voltage value to get amps.
Example:
600W ÷ 12V = 50A
This means the device may draw about 50 amps from a 12V system before efficiency loss.
How to Convert Amps to Watts
Sometimes you need to work in the opposite direction. This is useful when a device label shows amps, but you want to know the wattage.
Amps to Watts Formula
Amps to watts formula
Watts = Amps × Volts
Use this formula when you know current and voltage and need to calculate power.
Amps to Watts Example
Example 1:
10A × 12V = 120W
A 10 amp load on a 12V system uses about 120 watts.
Example 2:
10A × 120V = 1,200W
The same 10 amp current at 120V equals 1,200 watts.
This shows why both current and voltage are needed when converting between watts and amps.
| Amps | Watts at 12V | Watts at 24V | Watts at 48V | Watts at 120V |
|---|---|---|---|---|
| 1A | 12W | 24W | 48W | 120W |
| 5A | 60W | 120W | 240W | 600W |
| 10A | 120W | 240W | 480W | 1,200W |
| 20A | 240W | 480W | 960W | 2,400W |
| 30A | 360W | 720W | 1,440W | 3,600W |
Need to convert in the opposite direction? Read our full guide on ampere to watt calculation to learn how to convert amps to watts with formulas, examples, and common voltage tables.
Watts to Amps Calculator
Use this watts to amps calculator to quickly convert electrical power into current. Enter the watts and volts, then select DC or AC. For AC loads, you can also enter the power factor if you know it.
Result: Please enter watts and volts.
How to Use the Watts to Amps Calculator
First, enter the power value in watts. Next, enter the system voltage. Then choose DC or AC. For AC loads with motors or compressors, enter the power factor if you know it.
For most DC systems, the calculator uses this formula:
Calculator formula for DC power
Amps = Watts ÷ Volts
This is the most common formula for batteries, RV systems, solar systems, and other DC circuits.
For AC systems, the calculator can include power factor:
Calculator formula for AC power
Amps = Watts ÷ (Volts × Power Factor)
This gives a better estimate for AC loads where power factor is known.
When to Use a Watts to Amps Calculator
Use a watts to amps calculator when sizing wires, choosing fuses, checking breaker capacity, estimating battery current, sizing inverter cables, or planning RV and off grid power systems.
It is also useful when a device label shows watts, but you need to know how much current it may draw from a 12V, 24V, 48V, or 120V system.
Watts to Amps for Batteries, Solar and Inverters
Watts to amps conversion is especially important for battery systems, solar setups, and inverters. These systems often use low voltage DC power, so large wattage loads can create high current demand.
Battery Load Example
If a 12V battery system powers a 1,200W load, the current draw is:
Calculation: 1,200W ÷ 12V = 100A
A 1,200 watt load on a 12V battery system may draw about 100 amps before efficiency loss.
To estimate runtime, convert battery capacity into watt hours first.
Battery energy formula
Watt Hours = Amp Hours × Volts
This helps estimate how much energy a battery can store.
Example:
100Ah × 12V = 1,200Wh
A 12V 100Ah battery stores about 1,200 watt hours before real world losses.
Battery runtime formula
Runtime Hours = Battery Watt Hours ÷ Load Watts
This gives a basic runtime estimate before real world losses.
Example:
1,200Wh ÷ 120W = 10 hours
Real runtime may be lower because of inverter loss, temperature, battery age, and usable capacity limits.
Solar Charge Controller Example
A solar charge controller rated by amps can support different wattage depending on battery voltage. You can also reverse the calculation to estimate required controller current.
| Solar Output | Required Amps at 12V | Required Amps at 24V | Required Amps at 48V |
|---|---|---|---|
| 360W | 30A | 15A | 7.5A |
| 720W | 60A | 30A | 15A |
| 1,440W | 120A | 60A | 30A |
Always check the controller manual because rated solar input may depend on panel voltage, battery voltage, temperature, and controller design.
Inverter Current Example
An inverter changes DC battery power into AC household power. A 1,200W appliance may draw about 10 amps at 120V AC, but the battery side current can be much higher.
Example:
1,200W ÷ 120V = 10A on the AC side
1,200W ÷ 12V = 100A on the DC battery side before inverter loss
This is why inverter cables, fuses, and battery banks must be sized carefully.
FAQs About Watts to Amps
How do you convert watts to amps?
Use the formula Amps = Watts ÷ Volts. For example, 1,200 watts at 12 volts equals 100 amps.
How many amps is 100 watts?
It depends on voltage. At 12V, 100 watts is about 8.33 amps. At 24V, it is about 4.17 amps. At 120V, it is about 0.83 amps.
How many amps is 1,000 watts?
At 12V, 1,000 watts is about 83.3 amps. At 24V, it is about 41.7 amps. At 48V, it is about 20.8 amps. At 120V, it is about 8.3 amps.
How many amps is 1,500 watts?
At 12V, 1,500 watts is about 125 amps. At 24V, it is about 62.5 amps. At 120V, it is about 12.5 amps.
Can I convert watts to amps without voltage?
No. Voltage is required for watts to amps conversion. Watts measure power, while amps measure current. The formula needs both watts and volts.
Is DC watts to amps the same as AC watts to amps?
DC watts to amps usually uses Amps = Watts ÷ Volts. AC watts to amps may also require power factor, especially for motors, pumps, compressors, and power tools.
Conclusion
Watts to amps conversion is easy when you know the voltage. The main formula is Amps = Watts ÷ Volts. For AC devices, power factor may also be needed for a more accurate result.
Use the examples, tables, and watts to amps calculator above for quick estimates. For batteries, solar systems, and inverters, always check watts, current draw, voltage, and real operating conditions before choosing cables, fuses, charge controllers, or power equipment.
