What matters
Load percentage
A generator rarely uses fuel in a straight line. A lightly loaded diesel set can still burn a meaningful amount of fuel, while a well-loaded set often gives a better cost per kWh. For planning, use the manufacturer fuel curve at 25%, 50%, 75%, and 100% load where available. The Temporium calculator includes verified Atlas Copco QAS example curves, but the exact generator on your site should still be checked before a quote is confirmed.
Run hours
Daily run hours are often the biggest cost driver. A generator used for a short event load has a different cost profile from a welfare or site setup that runs all day, every day, for a season.
Diesel price
Use the latest pump price as a starting point, then adjust for delivered fuel, storage, refuelling labour, and any site-specific handling cost. The Temporium calculator uses the official UK weekly road fuel price where available, with a manual override.
Source quality
A manufacturer datasheet is better than a generic estimate. Retail listings and hire sheets can still help with early planning, but the safest workflow is to keep the calculation editable and attach the source to the enquiry.
Service allowance
Maintenance is easy to ignore in a quick quote. Add a service allowance per hour if you are comparing generator-only running against a battery-supported system.