Free practical sizing tools
Choose the right size before you buy.
RightSizeTools helps you estimate equipment size, battery runtime, trailer payload, generator wattage, and other practical buying decisions with simple calculators.
Featured calculators
Power
Generator Size Calculator
Estimate the generator wattage you need based on running watts, starting watts, and a safety margin.
Towing
Trailer Payload Calculator
Calculate remaining trailer payload after trailer weight, cargo, tongue weight, and safety margin.
Power
Battery Runtime Calculator
Estimate how long a battery or power station may run a device based on watt-hours, load, and efficiency.
Built for practical decisions
These calculators are meant for quick planning and comparison, not final engineering, code, or safety approval. Always verify product ratings, manufacturer specs, and local requirements before buying or using equipment.