Fuel & Engine
Consumption, range, and engine math — what you burn, and what the engine is actually doing.
Drivetrain & Shop
Gearing, tire size, and shop-floor math — how the drivetrain turns, and what it wears out.
Weight & Towing
What you can legally and safely pull or carry — payload, axle limits, and load space.
Road & Business
Planning and running costs for the trip itself — hours, distance, and cost per mile.
Which calculator do you need?
These group the way a working day does rather than by category. Most questions need two of them — what the load weighs and where it sits, or what the run costs and how many hours you have left to drive it.
- Before you hook up. Payload left, maximum tow rating and tongue or pin weight come from the towing and payload calculator. A legal gross weight can still fail a scale, so check the split with the axle weight calculator before you roll.
- Working out whether it fits. Deck space, load volume and pallet counts are in the cargo and load space calculator — which answers whether it fits, not whether it is secured.
- Planning the run. Drive time, arrival and stopping distance are in the trip planner, and the clock you are actually running against is in the hours of service calculator.
- Deciding whether the load pays. Fixed and variable costs become a real floor price in the cost per mile calculator, and the fuel half of that comes from the fuel and fluids calculator, which also covers DEF dose rate and coolant mix.
- Changing tire size or gearing. The gear ratio and tire calculator gives engine RPM at road speed and the speedometer error a size change introduces. Wear and the legal tread minimum are in the tire tread life calculator.
- In the shop. Displacement from bore and stroke is in the engine displacement calculator, and torque conversion, Ohm's law and battery runtime are in shop tools.
What these tools do, and what they do not
- They estimate; the regulation decides. Hours of service, weight limits and tread depth are enforced law. These tools help you plan against them, but an officer at a roadside inspection is reading the regulation, and each calculator links it.
- The manufacturer's plate outranks any rating here. Where a legal limit and a manufacturer limit disagree, the lower one governs, and no calculator can raise either.
- State limits differ from federal ones. Everything on this site is the federal baseline. Bridge formula exceptions, permits and state-specific caps sit on top of it.
- Nothing leaves your device. Recent calculations and saved results stay in your browser. There is no account and nothing is uploaded — see the Privacy Policy.
- They work in the cab. Every calculator switches between imperial and metric, and the reference tables and worked examples stay readable with JavaScript off.
Guides
Longer reference reading behind three of the calculators above.