Sizing a generator to your actual load matters more than the biggest kVA figure on the box.

A generator earns its keep when it is sized to what you actually plug into it. Get that wrong in either direction and you either pay for capacity you never use or run a machine that struggles under its own workload. Reading the spec sheet correctly is what separates the two.

kVA and kW are not the same thing

kVA is the total apparent power a generator can supply. kW is the real power your tools can actually draw from it once losses are accounted for. A generator rated in kVA alone will sound bigger, and sizing against tool loads means working from kW.

Inverter or conventional

An inverter generator converts its output electronically to a cleaner, more stable waveform, which matters for sensitive electronics and for equipment that reacts badly to voltage fluctuation. A conventional generator produces a rougher AC output straight from the alternator. For raw site tools that rarely matters; for anything with sensitive control electronics, it usually does.

Single-phase or three-phase

Most portable site tools and lighting run happily on single-phase output. Larger fixed machinery, and some welding plant, needs three-phase. Confirming which your equipment actually requires is worth doing before the generator turns up.

What happens at partial load

A generator run well below its rated output does not simply use proportionally less fuel. Diesel units in particular run less efficiently at light load, and persistent under-loading causes its own problems over time. Sizing to the load you will genuinely run keeps fuel consumption and wear in line with what the datasheet implies.

Generator buying guides covering these points in full are being written. Welding guides are live now and follow the same approach: what the spec actually means for your working pattern, and where the real trade-offs sit.