Plan your backup power: runtime, size, and cost in one place.
These calculators use typical values and conservative assumptions to help you think through generator runtime, approximate size, and estimated fuel cost for home backup, camping, or RV use.
They are planning tools only and do not replace manufacturer specifications, local codes, or professional advice.
Generator calculators
Start with a calculator that matches what you're trying to plan. You can always come back and switch tools.
1. Generator runtime calculator
Estimate how long your generator may run on a tank of fuel based on fuel type, tank size, usage level, and optional real-world conditions.
2. Rough generator size planner
Get a ballpark generator size based on your home size, how much of it you want to power, and whether you plan to run central air conditioning.
3. Generator fuel cost calculator
Estimate how much it costs to run your generator per hour and per day based on fuel type, usage level, and your local fuel price.
How to use these tools safely
- Not model-specific: These calculators use typical values, not brand-specific data. Always check your generator’s manual for official wattage, runtime, and fuel consumption information.
- Rough sizing and cost only: The size and cost planners are intentionally conservative and are meant to give you ballpark ranges. They are not a substitute for an electrician’s load calculation, fuel supplier advice, or local electrical code requirements.
- Plan with margin: It’s generally better for a generator to be slightly larger than you think you need and to have extra fuel on hand, especially for extended outages.
- Safety first: Always use proper transfer equipment, never backfeed a panel without a transfer switch, and never run a generator indoors or in enclosed spaces.
More generator calculators
Explore additional planners and comparison tools for RV setups, propane runtime, appliance loads, and more.
Generator guides & articles
Deeper walkthroughs that pair with the calculators above. Start with the topic that matches your situation.
- What size generator do I need for my house? – how to match generator size to your home and backup goals.
- How long will a generator run on 5 gallons of gas? – typical runtimes by generator size and load level.
- What can a 5000-watt generator run? – common appliances and circuits you can power with a mid-size portable unit.
- Best generator options for apartments & condos – safer backup approaches when you don't have a garage or yard.
- What can a 3,500-watt generator run? – smaller, popular size for basic backup and RV use.
- How long will a generator run on propane? – propane runtime basics and typical cylinder & tank sizes.
- What size generator do I need for RV & camping? – quiet, right-sized options for RVs, travel trailers, and campsites.
- How to connect a generator to your home safely – transfer switches, interlocks, and safe connection options.
- Portable vs. standby generator: which is better? – pros, cons, and costs of each approach.
- Whole-home generator sizing guide – bigger picture planning if you want to power most or all of your home.
- How loud is a generator? – typical noise levels, distance effects, and neighbor-friendly choices.
- Can you run a generator in the rain? – safety basics for wet weather and storm use.
- Where should you place a generator? – safe distance, ventilation, and placement tips.
- What size extension cord do you need? – cord gauge basics for generator loads and distance.
- Can a generator damage appliances? – power quality, surges, and protection ideas.
- Generator fuel storage guide – planning gasoline and propane storage for outages.
- Generator wattage chart – quick reference wattage ranges for common appliances.