Enter both values to calculate watts
Volt-Amperes (VA)
Power Factor (PF)
Common:
Watts (W)
Result will appear here
Understanding Apparent vs Real Power
VA and watts differ by the power factor:
- Real Power (W) = Apparent Power (VA) × Power Factor
- Apparent Power (VA) = Real Power (W) ÷ Power Factor
- Power Factor ranges from 0 to 1 (1 = perfectly efficient)
For Inverter Sizing
Understanding these relationships helps you:
- Size inverters correctly - Always size for VA, not watts
- Understand UPS ratings - VA tells the full story
- Account for motors - They have low power factor (0.6-0.8)
- Plan for inductive loads - Electronics often have PF around 0.9
Real-World Solar Examples
3,000VA Inverter Real Power
A 3,000VA inverter with power factor 0.8 delivers a maximum of 2,400W usable power. To keep solar matched, you need at least 2,400W of panels at peak.
Workshop with Mixed Loads
Resistive loads (lights, heaters) at PF ~1.0: 1,000VA = 1,000W. A 1,500W table saw at PF ~0.7 draws ~2,143VA. A 5,000VA inverter at PF 0.8 delivers 4,000W, but motor loads can push VA above 5,000 even when watts are under 4,000.
UPS for Solar Monitoring
A 1,000VA UPS at PF 0.6 delivers only 600W real power. At PF 0.9: 900W. A 500W monitoring setup at PF 0.7 needs 714VA — a 1,000VA/0.6PF UPS barely covers it.
When You'll Need This Conversion
- Buying an Off-Grid Inverter — Inverters are marketed in VA, but appliances are rated in watts. A 2,000VA inverter does not deliver 2,000W — multiply by power factor (0.8 typical, 0.6 for budget units) to find actual usable watts.
- Calculating True Hybrid Inverter Load — A 5,000VA hybrid inverter with PF 0.8 delivers 4,000W. Adding 4,500W of appliances triggers overload protection. The VA-to-watts conversion reveals the mismatch before it causes problems.
- Comparing Inverter Brands — Brand A sells a "5000W" inverter (5,000VA at PF 0.8 = 4,000W real). Brand B sells a "5000W" at PF 1.0 = 5,000W real. Always check the spec sheet for both VA and watt ratings.
Solar Tips & Common Mistakes
Read the Inverter Spec Sheet Carefully: Many solar inverters, especially budget off-grid models, advertise VA prominently while the watt rating is buried. A "5kW inverter" at 5kVA and PF 0.8 delivers only 4,000W.
Power Factor Varies by Load Type: Resistive loads (heaters, kettles): PF ~1.0. Motors (pumps, tools): PF 0.5–0.85. Electronics: PF 0.55–0.95. Mostly resistive loads mean more usable watts from the same VA-rated inverter.
Surge VA vs Continuous VA: Inverters have a surge (peak) VA rating, typically 2× continuous for 5–10 seconds. A 3,000VA continuous / 6,000VA surge inverter can start a motor drawing 5,000VA at startup.
Solar Calculators
Related Conversion Calculators
Last updated: January 5, 2026
