Convert Watts to Volt Amps
Enter load details to calculate VA, kVA, VAR, and an optional current estimate.
Example Data Table
These examples show how power factor changes apparent power. The same watt load can require different VA capacity.
| Watts | Power Factor | System | Calculated VA | Current Example |
|---|---|---|---|---|
| 600 W | 1.00 | DC | 600 VA | 5.00 A at 120 V |
| 900 W | 0.90 | Single-Phase AC | 1,000 VA | 4.35 A at 230 V |
| 1,200 W | 0.80 | Single-Phase AC | 1,500 VA | 12.50 A at 120 V |
| 9,000 W | 0.90 | Three-Phase AC | 10,000 VA | 14.43 A at 400 V |
Formula Used
AC apparent power: VA = Watts ÷ Power Factor
DC apparent power: VA = Watts
Three-phase current: Current = VA ÷ (√3 × line-to-line voltage)
Power factor is the relationship between real power and apparent power. It is normally written from zero to one. A value closer to one means watts and VA are closer together.
For example, 1,000 watts at a 0.80 power factor gives 1,250 VA. Divide 1,000 by 0.80. The answer shows the capacity required from the supply.
How to Use This Calculator
- Enter the real power rating in watts.
- Enter power factor as a decimal or percentage.
- Select DC, single-phase AC, or three-phase AC.
- Add voltage when you also need an estimated current.
- Choose a rounding level and select the calculate button.
- Review VA, kVA, VAR, and the applied formula.
- Save the result as CSV or print it as PDF.
Watts and Volt Amps Explained
Real Power and Apparent Power
Watts and volt amps describe different parts of electrical power. Watts measure real power. Real power performs useful work. It produces heat, motion, light, or computing output. Volt amps measure apparent power. Apparent power is the total electrical capacity supplied to a load.
The difference matters in alternating current systems. Many loads do not use voltage and current perfectly together. Motors, transformers, compressors, and power supplies often create a timing shift. That shift is called the power factor. A lower power factor means the equipment needs more volt amps for the same watt output.
A watts to volt amps calculation helps select generators, inverters, transformers, cables, and circuit protection. It prevents undersized equipment. It also helps compare nameplates. Some devices list watts. Others list volt amps. This calculator connects both ratings through power factor.
DC and Single-Phase Results
For a DC circuit, watts and volt amps are normally equal. Voltage and current have no phase shift. The power factor is treated as one. A 600 watt DC load therefore uses 600 volt amps. This simple relationship does not usually apply to AC loads.
For single-phase AC, divide watts by power factor. A 900 watt appliance with a 0.90 power factor needs 1,000 volt amps. The same appliance at 0.60 power factor needs 1,500 volt amps. The real power remains 900 watts. However, the supply must carry more apparent power.
Three-Phase and Current Estimates
Three-phase calculations use the same apparent-power relationship. The current estimate changes because three phases share the load. Enter line-to-line voltage when calculating current. The calculator divides apparent power by the voltage times the square root of three. This gives a useful planning estimate for balanced loads.
Power factor can appear as a decimal or a percentage. A value of 0.85 equals 85 percent. Residential resistance heaters often have power factors near one. Inductive machinery may have lower values. A nameplate, manufacturer sheet, or power meter can provide the best value. Avoid guessing for critical design work.
Use Results With Care
The optional voltage field adds an estimated current result. This helps with conductor and breaker planning. It is not a complete engineering design. Starting current, harmonics, temperature, code rules, and load diversity can change the final selection. Consult a qualified electrician for permanent installations.
Choose a suitable rounding level for your task. Two decimals work well for estimates. More decimals can help when checking equipment data. Fewer decimals make labels easier to read. Keep the original watts and power factor with your saved result. They show how the apparent-power value was obtained.
Use the calculator as a quick conversion tool. Then confirm ratings against equipment documentation. Match the system type carefully. Check whether voltage is single-phase or line-to-line three-phase. Use apparent power for supply capacity. Use watts when estimating consumed energy. These two values work together for safer electrical planning.
Review results after loading changes. Confirm voltage before choosing final equipment sizes. Record assumptions for later checks.
Frequently Asked Questions
What does volt amps mean?
Volt amps, written VA, measure apparent power. They describe the voltage-current capacity a source, transformer, inverter, or generator must provide.
How do I convert watts to volt amps?
For AC loads, divide watts by power factor. For DC loads, VA normally equals watts because the power factor is one.
What power factor should I use?
Use the value on the equipment nameplate or technical sheet. When no value is available, use a cautious estimate and confirm before choosing permanent equipment.
Are watts and VA always equal?
No. They are equal for DC and many resistive AC loads. They differ when an AC load has a power factor below one.
Can this calculator estimate current?
Yes. Enter voltage to receive an estimated current. Single-phase and DC use VA divided by voltage. Three-phase uses VA divided by voltage times the square root of three.
Which voltage should I enter for three phase?
Enter the line-to-line voltage for a standard three-phase system. Verify the supply rating before using the current estimate for installation planning.
Why does a low power factor increase VA?
A low power factor means voltage and current are less aligned. The circuit must carry more apparent power to deliver the same real watts.
Can I use this for generators and inverters?
Yes. VA is useful when comparing supply capacity. Include startup surge, load changes, and the manufacturer rating before selecting a generator or inverter.
Does this replace electrical design work?
No. It provides a fast planning estimate. Final equipment selection must consider codes, conductor limits, protection, harmonics, temperature, and installation conditions.
What rounding option should I choose?
Use two decimals for general estimates. Use more decimals for technical checks. Use fewer decimals when you need simple labels or summary reports.
Can I save my calculation?
Use the CSV button to save values. The print option can create a PDF through your browser. It supports consistent planning, clearer checks, and better decisions.