Generator guides and free calculators
Size, run and troubleshoot your generator with confidence
Free calculators that show their formulas, plain-English guides and safety-first advice for homeowners, RV owners and small businesses.
- Formulas explained
- Worked examples
- No sign-up
Free generator and electricity calculators
Every calculator shows its formula and a worked example, so you can check the numbers yourself.
Plan your backup power in three steps
Work from what you need to run to what it will cost, in this order.
Add up your load
List the appliances you want to run and total their running watts and starting surge.
Generator Load Calculator →Choose the right size
Turn your load into a minimum generator rating with a sensible reserve for starting loads.
Generator Size Calculator →Plan fuel and runtime
Estimate fuel per hour, how long a tank lasts and what an outage will cost to run.
Fuel Consumption Calculator →Browse by topic
From choosing a generator to keeping it running for years.
Generator won’t cooperate?
Step-by-step fixes for the most common generator problems, with quick diagnosis tables.
Generator Overload: Why the Breaker Keeps Tripping (and How to Stop It)
Overloading is the most common reason a generator's breaker trips or an inverter generator cuts out. The good news is that it is easy…
How to Store a Generator: Short-Term, Long-Term and Reviving One That Sat
Most generator problems are really storage problems. Fuel goes stale, carburetors gum up, batteries die and the generator will not start when the next…
Generator Keeps Shutting Off or Stalling: Causes and Fixes
A generator that starts fine and then cuts out is frustrating, but the cause is usually simple. The pattern tells you a lot: does…
Generator Surging or Hunting: Causes and How to Fix It
When a generator surges (also called hunting), the engine speed rises and falls in a repeating pattern. You hear the revs go up and…
Generator Running But No Power: Causes and Fixes
The engine is running smoothly, but nothing works when you plug in. This is almost always an electrical problem rather than an engine problem.…
Generator Won’t Start: Causes and Fixes (Step-by-Step Checklist)
A generator that will not start almost always has one of four problems: fuel is not reaching the engine, there is no spark, the…
Latest guides
Sizing, fuel, runtime, installation and maintenance explained in plain English.
How Does a Generator Work? Types, Parts and Uses
A generator does not create energy. It converts mechanical energy, usually from a fuel-burning engine, into electrical energy. The principle has been the same…
How to Calculate Generator Runtime
Knowing how to calculate generator runtime can help you determine how long a generator can operate before it needs more fuel. The calculation is…
How Much Fuel Does a Generator Use Per Hour?
A generator's fuel consumption depends on its size, fuel type, electrical load, engine efficiency, and operating conditions. There is no single fuel consumption rate…
How Long Can a Generator Run Continuously?
How long a generator runs on a full tank depends on several factors, including the generator's fuel tank capacity, fuel type, engine efficiency, and…
Generac Home Generators: Types, Features and What to Know Before You Buy
Generac is the best-known name in home standby generators, the permanently installed kind that start by themselves when the power fails. This guide explains…
DeWalt 5700-Watt Generator: Features and Uses
The DeWalt 5700-watt portable generator is aimed at job sites and home backup. This guide covers its main features, where it fits, and what…
Generator safety basics
Every year people are hurt by generators used indoors or connected the wrong way. These three rules prevent most of it.
Read the safety guide- Run it outdoors, away from the house. Carbon monoxide from the exhaust can be fatal within minutes. Keep the generator at least 20 feet from doors, windows and vents.
- Never backfeed through a wall outlet. Use a transfer switch or interlock installed by a licensed electrician. See safe ways to connect a generator to a house.
- Install battery-powered CO alarms on every level of your home and test them regularly.
How we write our guides
Formulas, not guesses
Every calculator shows the math and a worked example, so you can verify any result by hand.
Sources you can check
Figures are based on manufacturer specifications, published fuel data and electrical codes, and we say when something is an estimate.
Independent advice
No manufacturer or retailer pays for rankings, reviews or recommendations on this site.