kVA, kW, and amps on a generator nameplate
Published October 6, 2026.
Built by Jeremy Panasuk.
At power factor 1.0 the kilowatt and the kilovolt-ampere are the same number. Amps are that wattage divided by the voltage on the same row. This page does not give a three-phase formula.
What the two Generac sheets print
The owner's manual puts "Rated Power @1.0 Power Factor" on one line: 6.5 kW for the GP6500 / GP6500E column and 8.0 kW for the GP8000E column. The next line is surge power, 8.125 kVA and 10.0 kVA. Rated AC voltage is 120/240. Phase is single phase. Because the rated line is already at power factor 1.0, the rated kilowatt and the rated kilovolt-ampere are the same quantity: 6.5 kW is 6.5 kVA, and 8.0 kW is 8.0 kVA. The surge line is written in kVA. At the same power factor of 1.0, 8.125 kVA is 8,125 W, which is the starting-watts figure on the GP6500 product listing.
That product listing, part number 10000032664, model G007672-3, prints AC rated output running watts 6,500 and AC maximum output starting watts 8,125. Rated 120/240 VAC amperage is 54.2 / 27.0. Check those amps against the running watts, not against the surge: 6,500 / 120 = 54.17, which rounds to the printed 54.2 A, and 6,500 / 240 = 27.08, which rounds to the printed 27.0 A. Dividing the 8,125 W start by those voltages is a different current. The listing does not print that starting current.
The owner's manual also prints current at 240 V and current at 120 V, but a text conversion of that table splits the columns. This page uses the product listing's 54.2 A and 27.0 A for the GP6500 and does not assign a second pair of amps to the GP8000E from that conversion. Do not mix these Generac amps with the Kubota amps below. They are different machines that both happen to print a 6.5 kW line.
The same power factor on Kubota's sheet
Kubota Engine America's GL7000-USA spec sheet lists standby output of 7.0 kVA (7.0 kW) and prime output of 6.5 kVA (6.5 kW) at 120/240 V, power factor 1.0. The printed amperage, 54.2 A at 120 V and 27.1 A at 240 V, matches the 6.5 kW prime rating: 6,500 / 120 = 54.17 rounds to 54.2, and 6,500 / 240 = 27.08 rounds to 27.1. Generac's GP6500 listing rounds the 240 V line to 27.0. Kubota's sheet rounds it to 27.1. Those are not interchangeable. The Kubota page walks the standby-versus-prime trap: Kubota standby generator.
Single-phase amps, and where this stops
On these sheets, at power factor 1.0, kW equals kVA. Single-phase amps equal watts divided by the voltage on that row. A transfer switch uses the same multiplication in the other direction: 30 A × 240 V = 7,200 W, and 50 A × 240 V = 12,000 W. That is the switch's ceiling at 240 V. It is not a generator's rated watts.
A building service, a three-phase set, or a life-safety load is not this division. How to size an industrial generator stops at a jobsite load list and says that case needs an engineer's load study. This page does not add a three-phase formula.
The home calculator still works in watts. Convert a nameplate only after you know which row you are reading: rated versus surge, and 120 V versus 240 V.
Run a portable outdoors only, at least 20 feet from the house, never inside, including a garage with the door open (CPSC). A transfer switch and a permanent connection take a licensed electrician and a permit where local code requires one.
Compiled with AI assistance from the sources below. Spot an error? Email [email protected].