SettingsSettings for this calculationUS
The real power demand in kilowatts.
The load's demand in kW, from a load schedule or the equipment's ratings. A lower power factor means more kVA for the same kW, so a motor-heavy load needs a larger supply than its kW figure suggests.
The load's power factor: 1 for resistive heating, lower for motors. It opens on 0.8, the factor three-phase generator sets are rated at; a single-phase set is rated at 1.
Take it from the equipment's nameplate, a load schedule or a power-quality meter. The kVA answer is the kW divided by it, so the lower the power factor the more apparent power the supply has to carry for the same work — at 0.7, about 43% more than at 1. Lightly loaded induction motors fall well below their full-load figure, which is worth remembering on a site where machines idle.
Apparent power
100 kVA
kVA = kW ÷ power factor. The kvar row is the reactive part the supply carries on top of the working current; a generator has to be checked against its kVA as well as its kW, taking whichever binds first. Motor inrush frequently determines generator size rather than running load, so check starting current separately.
- Real power entered
- 80 kW
- Power factor applied
- 0.8
- Reactive power, kW × tan(arccos PF)
- 60 kvar
They open the calculator with your figures already in it
kW to kVA Calculator: 100 kVA — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- Apparent power = real power / power factor; kVA = kW / PF, and the reactive part is kW x tan(arccos PF)
- Cummins Inc., 2022 Global Product Guide — Power Generation Products (GLM-5763-EN): the diesel sets are listed with their kWe at 0.8 of their kVA (the C20D6 at 25 kVA and 20 kWe standby, the C30D6 at 37.5 kVA and 30 kWe), the three-phase convention the opening 0.8 follows; the single-phase sets are listed in kW with a current that is the kW divided by the volts, so their kVA and kW are the same number (the RV QG 2800 at 2.8 kW and 23.3 A on 120 V, the RV QG 2300 at 2.3 kW and 10 A on 230 V, the QD5000 at 4.8 kW and 21 A on 230 V)
- Cummins Inc., Pre-Configured Diesel generator sets, specification sheet NAS-6437-EN (12/19): the C20 D6 set for 120/240 V, 1 phase, is 20 kW and 20 kVA standby at 60 Hz — the model the 2022 guide lists at 25 kVA and 20 kWe
Inputs used
- Real power (kW)
- 80
- Power factor
- 0.8
Intermediate steps
- Real power entered
- 80 kW
- Power factor applied
- 0.8
- Reactive power, kW × tan(arccos PF)
- 60 kvar
Confidence note: kVA = kW ÷ power factor. The kvar row is the reactive part the supply carries on top of the working current; a generator has to be checked against its kVA as well as its kW, taking whichever binds first. Motor inrush frequently determines generator size rather than running load, so check starting current separately.
What this calculation does not cover
- The answer scales inversely with the power factor entered, and the field opens on 0.8 for a set's badge, not because any load runs there. Three-phase generator sets are conventionally rated at 0.8 — Cummins lists the C20D6 at 25 kVA and 20 kWe — while single-phase sets are rated at 1, where kVA and kW are the same number. A motor-heavy site below 0.8 needs more kVA than the opening answer shows, and a corrected or largely resistive one needs less.
- This is a unit conversion, not a load calculation. It takes the kW figure you type at face value and applies no diversity, no demand factors and no maximum-demand assessment, so it does not stand in for a proper load assessment before ordering a supply, transformer or generator set.
- Steady-state only. Motor inrush, step-load acceptance and transient voltage dip are not modelled, and on a generator these frequently set the machine size well above the running kVA calculated here.
- No voltage, current or phase comes out of this. The result does not size conductors, protective devices or switchgear; the current at a given voltage, single-phase or three-phase, is a separate step on the watts, amps and kVA page.
- Distorting loads such as variable-speed drives, UPS and some LED and IT supplies draw harmonic current that a single power factor does not describe. Nothing here derates the machine for that content, or for altitude and ambient temperature on a generator.
Add the equipment this sizes
This result is a specification — 100 kVA — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-10-05 · v1.1.0
Regulatory standards & verification citations3
- Apparent power = real power / power factor; kVA = kW / PF, and the reactive part is kW x tan(arccos PF)
- Cummins Inc., 2022 Global Product Guide — Power Generation Products (GLM-5763-EN): the diesel sets are listed with their kWe at 0.8 of their kVA (the C20D6 at 25 kVA and 20 kWe standby, the C30D6 at 37.5 kVA and 30 kWe), the three-phase convention the opening 0.8 follows; the single-phase sets are listed in kW with a current that is the kW divided by the volts, so their kVA and kW are the same number (the RV QG 2800 at 2.8 kW and 23.3 A on 120 V, the RV QG 2300 at 2.3 kW and 10 A on 230 V, the QD5000 at 4.8 kW and 21 A on 230 V)
- Cummins Inc., Pre-Configured Diesel generator sets, specification sheet NAS-6437-EN (12/19): the C20 D6 set for 120/240 V, 1 phase, is 20 kW and 20 kVA standby at 60 Hz — the model the 2022 guide lists at 25 kVA and 20 kWe
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Sizing a generator, transformer or supply from a known load means working from real power back to apparent power, because it is apparent power that the conductors and switchgear actually have to carry. Dividing by the power factor does that, and the worse the power factor the larger the required capacity for identical useful output — current flows and heats cables whether or not it is doing work. The field opens on 0.8, the factor three-phase sets are conventionally badged at — a single-phase set is rated at 1, its kVA and kW the same number — and the load's own figure belongs in it once it is known. Two checks belong alongside the arithmetic. A generator should be assessed against both its kW and its kVA rating, taking whichever binds first. And motor starting current, which can be several times the running figure, frequently sets the machine size regardless of what the steady-state calculation says.