Engineering tools
Generator Engineering Calculators
Free tools for application and facilities engineers spec'ing backup power. Sizing, fuel runtime, NEC voltage drop, and motor starting — all browser-side, no signup, no tracking of inputs.
Generator Sizing Calculator
Estimate the standby kW you need from a basic load profile — continuous load, HVAC tons, and largest motor.
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Fuel Runtime Calculator
How long will your generator run on a tank? Estimate runtime by load percent for diesel, or BTU/hr demand for natural gas.
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NEC Voltage Drop Calculator
NEC Chapter 9 Table 9 voltage drop for copper or aluminum, single- or three-phase, with 3% / 5% guidance verdicts.
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Motor Starting kVA Estimator
Estimate locked-rotor kVA from motor HP and NEMA code letter, then size the alternator's starting capability.
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These calculators are estimates intended as starting points for design conversations and budgetary spec'ing. For final sizing on regulated occupancies (NFPA 110 Level 1 healthcare, OSHPD-certified installations, hyperscale data centers), always verify with a formal load study and the OEM's sizing tool (Cat Diesel SpecSizer, Cummins GenSize, Kohler PowerSize, etc.).
Need help running a load study?
Our application engineers help size, spec, and source backup power for commercial, industrial, and mission-critical sites.