Diesel generator hire is priced by kW and by hire length, and the spread is wide: a 20 kW tow-behind sits near $150 to $300 a day, a 100 kW set near $400 to $700, and a 500 kW containerised unit above $1,000. Fuel is the line that surprises people, because a loaded generator burns diesel by the gallon per hour and is billed on top of the rate.
Size on starting load, not running load
Motors draw several times their running current for the first seconds of a start, so a set sized only to the steady load will trip or stall when the first compressor kicks in. List every motor, its horsepower and whether it can be staggered. Yards size from that list; a generator chosen from a total watt figure alone is the classic undersizing mistake.
What the day rate does not include
Cable, camlock tails, a distribution box and a spider box are separate line items and often add a third to the rate on a small set. Fuel is billed by consumption or returned full. A fuel tank or a bunded trailer for a long job is another line, and after-hours refuelling is a call-out charge on most contracts.
Fuel burn is the number to budget
A rough field figure is 0.07 gallons per hour per kW at full load, so a 100 kW set working hard burns near seven gallons an hour and a 500 kW set closer to thirty-five. Sets rarely run at full load, but budget from load rather than from rating and you will not be caught out on a week-long hire.
Tow-behind, skid or containerised
Tow-behind sets to about 100 kW travel on their own trailer and can be dropped by a pickup. Larger skid-mounted sets need a truck with a crane or a forklift on site. Containerised sets above 300 kW need a lowboy and a clear laydown area, which is why delivery on the big ones is quoted per job rather than per mile.
Questions people ask about diesel generator rental
What size generator do I need for a construction site?
A small site running hand tools, lighting and a compressor commonly sits at 20 to 45 kW. Add a tower crane, a concrete pump or temporary heat and you are into 100 kW and above. Give the yard a motor list rather than a wattage total.
Is fuel included in the rental?
No. It is either billed on consumption from the hour meter or handled on a full-to-full basis. On a set running continuously, fuel often costs more over a week than the hire itself.
Can I run a rental generator overnight unattended?
Most rental sets are built for it, with tanks sized for eight to twenty-four hours and automatic shutdowns for low oil and high temperature. Check the run time at your actual load rather than the tank's rated hours, which assume a lighter load.