Electrical Calculations
Watts to VA Calculator
Convert real power in watts to apparent power in volt-amperes using power factor.
How to Convert Watts to VA
To convert watts to volt-amperes, divide the real power in watts by the power factor.
The formula is:
VA = Watts ÷ Power Factor
Watts represent real electrical power, while VA represents apparent electrical power. Because the two values are affected by power factor, you need to know the power factor to accurately convert watts to VA.
Example: Convert 800 Watts to VA
Suppose an electrical load uses 800 watts and has a power factor of 0.8.
VA = 800 ÷ 0.8
VA = 1,000
Therefore, 800 watts at a power factor of 0.8 is equal to 1,000 VA.
Example: Convert 900 Watts to VA
For a 900 watt load with a power factor of 0.9:
VA = 900 ÷ 0.9
VA = 1,000
Therefore, 900 watts at a power factor of 0.9 is equal to 1,000 VA.
Watts to VA Conversion Table
The following table shows common watts-to-VA conversions at power factors of 0.8, 0.9, and 1.0.
| Watts | VA at PF 0.8 | VA at PF 0.9 | VA at PF 1.0 |
|---|---|---|---|
| 100 W | 125 VA | 111.11 VA | 100 VA |
| 250 W | 312.5 VA | 277.78 VA | 250 VA |
| 500 W | 625 VA | 555.56 VA | 500 VA |
| 800 W | 1,000 VA | 888.89 VA | 800 VA |
| 1,000 W | 1,250 VA | 1,111.11 VA | 1,000 VA |
| 1,500 W | 1,875 VA | 1,666.67 VA | 1,500 VA |
| 2,000 W | 2,500 VA | 2,222.22 VA | 2,000 VA |
| 3,000 W | 3,750 VA | 3,333.33 VA | 3,000 VA |
| 5,000 W | 6,250 VA | 5,555.56 VA | 5,000 VA |
| 10,000 W | 12,500 VA | 11,111.11 VA | 10,000 VA |
The required VA increases as power factor decreases. Use the calculator above when your watt value or power factor is different from the values shown in the table.
What Is a Watt?
A watt is the standard unit of real electrical power.
Real power represents the electrical energy that is actually converted into useful output such as heat, light, mechanical motion, cooling, computing, or another form of work.
One kilowatt is equal to 1,000 watts.
What Is VA?
VA stands for volt-amperes and measures apparent electrical power in an AC electrical system.
Apparent power represents the total combination of voltage and current supplied to an electrical load.
UPS systems, power supplies, transformers, inverters, and other electrical equipment are often rated in VA or kVA.
One kVA is equal to 1,000 VA.
Why Is Power Factor Required?
Power factor is required because watts measure real power while VA measures apparent power.
The relationship is:
Watts = VA × Power Factor
Rearranging the formula gives:
VA = Watts ÷ Power Factor
Without power factor, you cannot accurately determine apparent power from watts alone.
How Does Power Factor Affect VA?
A lower power factor means more apparent power is required to supply the same real power.
For example, a 1,000 watt load at a power factor of 1 requires:
1,000 ÷ 1 = 1,000 VA
The same 1,000 watt load at a power factor of 0.8 requires:
1,000 ÷ 0.8 = 1,250 VA
This difference is important when comparing real load power with the VA capacity of equipment such as UPS systems and power supplies.
Does Single Phase or Three Phase Affect Watts to VA Conversion?
No. Electrical phase does not change the direct watts-to-VA conversion.
The formula remains:
VA = Watts ÷ Power Factor
Phase and voltage become necessary when current also needs to be calculated, but they are not required for a direct conversion between watts and VA.
Watts vs VA
Watts and VA are both measurements of electrical power, but they represent different types of power.
Watts represent real power, while VA represents apparent power.
At a power factor of 1:
1 watt = 1 VA
At a power factor of 0.8:
800 watts = 1,000 VA
This is why the power factor must be considered when converting between watts and VA.
Watts to VA vs Watts to kVA
Watts to VA and watts to kVA calculate the same type of apparent electrical power, but the output units are different.
For VA:
VA = Watts ÷ Power Factor
For kVA:
kVA = Watts ÷ (1000 × Power Factor)
For example, 8,000 watts at a power factor of 0.8 is equal to 10,000 VA or 10 kVA.
For larger apparent power values, you can use our
Watts to kVA Calculator
.
Common Uses of a Watts to VA Calculator
A watts to VA calculator is useful when an electrical load is specified in watts but the equipment supplying it is rated in volt-amperes.
Common applications include UPS systems, computer equipment, servers, networking equipment, power supplies, inverters, transformers, communications equipment, office electronics, and other AC electrical loads.
The calculation can help with preliminary comparisons between a load’s real power requirement and the apparent power capacity of electrical equipment.
Frequently Asked Questions
How do I convert watts to VA?
Divide watts by the power factor.
VA = Watts ÷ Power Factor
How many VA is 100 watts?
At a power factor of 1, 100 watts equals 100 VA. At a power factor of 0.8, 100 watts equals 125 VA.
How many VA is 500 watts?
At a power factor of 0.8, 500 watts is equal to 625 VA.
How many VA is 800 watts?
At a power factor of 0.8, 800 watts is equal to 1,000 VA.
How many VA is 1,000 watts?
At a power factor of 1, 1,000 watts equals 1,000 VA. At a power factor of 0.8, 1,000 watts equals 1,250 VA.
How many VA is 2,000 watts at 0.8 power factor?
2,000 watts at a power factor of 0.8 is equal to 2,500 VA.
How many VA is 5,000 watts at 0.8 power factor?
5,000 watts at a power factor of 0.8 is equal to 6,250 VA.
How many VA is 10,000 watts at 0.8 power factor?
10,000 watts at a power factor of 0.8 is equal to 12,500 VA.
Is VA the same as watts?
Not necessarily. VA measures apparent power, while watts measure real power.
They have the same numerical value only when the power factor is 1.
Can VA be lower than watts?
Under the normal electrical power relationship used by this calculator, no. Because power factor does not exceed 1, apparent power in VA will be equal to or greater than real power in watts.
Do I need voltage to convert watts to VA?
No. Voltage is not needed for a direct watts-to-VA conversion.
Do I need to know whether the system is single phase or three phase?
No. Electrical phase does not affect the direct conversion from watts to VA.
What power factor should I use?
Use the actual power factor of the equipment or connected load whenever possible.
Check the equipment nameplate, technical specifications, manufacturer documentation, UPS display, or a suitable electrical measurement when available.
Can I use this calculator for a UPS?
Yes. A watts to VA calculation can help compare the real power requirement of connected equipment with the VA capacity of a UPS.
However, UPS sizing should consider both the UPS watt rating and VA rating. Battery runtime, overload capability, redundancy requirements, future expansion, and manufacturer recommendations should also be considered.
Can I use this calculator for computer equipment?
Yes. The calculator can help estimate the apparent power of computers, servers, monitors, networking devices, and other electronic equipment when their watt consumption and power factor are known.
Related Electrical Calculators
Continue your electrical calculations with these related tools:
Electrical Calculation Disclaimer
This Watts to VA Calculator is provided for informational, educational, and preliminary planning purposes. Calculated values may be rounded.
Actual electrical conditions may vary because of power factor variation, equipment efficiency, load characteristics, harmonics, voltage conditions, operating conditions, and other factors.
Equipment such as UPS systems, transformers, power supplies, inverters, and other electrical devices should be selected using the manufacturer’s actual ratings and specifications.
Electrical installations may also require consideration of conductor ratings, protective devices, equipment specifications, applicable electrical codes, manufacturer requirements, installation conditions, and safety factors.
Consult a qualified electrical professional when making final electrical installation, equipment selection, wiring, conductor sizing, protection, or power system decisions.
