Know the right size before you buy.
Free guided calculators for generators, power stations, trailers, air compressors, concrete, gravel, extension cords, shop equipment, and more.
Popular tools
Start with the calculators most likely to prevent buying the wrong size equipment or materials.
Home Generator Size
Estimate the generator size needed for essential home backup loads during a power outage.
Open calculator → Power & BackupCamping & RV Generator
Estimate generator wattage for RV, camping, cabin, and outdoor power needs.
Open calculator → Power & BackupPower Station Runtime
Estimate how long a portable power station can run common devices.
Open calculator → Power & BackupBattery Runtime
Estimate battery runtime from watt-hours, load, and efficiency.
Open calculator → Towing & TrailersTrailer Payload
Estimate remaining trailer payload after trailer weight, cargo, and reserve margin.
Open calculator → Towing & TrailersTongue Weight
Estimate target trailer tongue weight from loaded trailer weight and tongue-weight percentage.
Open calculator →Designed for normal people, not spec sheets.
Each calculator uses plain-English inputs, common presets, clear units, and optional advanced settings. You can start with what you know, then refine the estimate if you have exact ratings.
Calculator categories
Tools are grouped by the kind of decision you are trying to make.