Generator size calculator
Add the equipment that has to keep running. This estimates your running load, the peak when your largest motor starts, and the generator size that fits.
Talk it through with usTwo figures matter. The first is running load — the sum of everything drawing power at once. The second is the starting peak, which is what happens when your largest motor kicks in while the rest is already running. Motors started across the line pull several times their running current for a moment, and that surge is what actually decides the size.
The calculator takes the running total, adds the extra draw from the single largest starting load, applies 25 percent headroom, then rounds up to a size gensets are actually built in. It deliberately does not assume every motor starts simultaneously, because in practice they rarely do.
What this cannot see: your service voltage and phase, whether a soft starter or VFD is fitted, the duty cycle, the ambient conditions, or whether the generator you are looking at is standby or prime rated. Those change the answer. Read the full sizing guide for what each of them does, then call and we will confirm it against the real equipment.
It adds the running watts of everything you select, then adds the extra current drawn when your single largest motor starts while the rest is already running. It applies 25 percent headroom to that peak and rounds up to the next standard generator size.
It is a planning estimate, good enough to tell you whether you are shopping for a 30 kW or a 150 kW machine. It is not an electrical specification. Real sizing uses your actual nameplates, service voltage and phase, whether motors are soft-started, and the rating basis of the specific generator.
Motors draw several times their running current for a moment at startup, commonly three to six times. That brief surge is what stalls an undersized generator, so it drives the size even though it lasts a second or two.
Running a generator at its absolute limit leaves nothing for adding equipment later and no margin for error in the estimate. Headroom of around 25 percent is a sensible allowance. Going far beyond that is its own problem, because a lightly loaded diesel can wet stack.
Call us with it. We will check it against your actual equipment, tell you what is genuinely available in that range, and quote it delivered to your Florida address.
Generator sales and delivery in Florida