About this trailer axle capacity calculator
Trailer GVWR and axle ratings are related but they are not interchangeable. This tool estimates the weight carried by the axle group after accounting for estimated tongue weight, then compares it with installed axle capacity.
How the calculation works
- Enter loaded trailer weight and tongue-weight percentage.
- Enter axle count and the rating of each axle.
- The calculator estimates weight on the axle group.
- It compares estimated axle load with combined axle rating and reports a margin.
Get a better result
- Axles can be unevenly loaded even when the group total is below its rating.
- Verify the axle tag, tire/wheel ratings and trailer certification label.
- Scale individual axles when precise distribution matters.
Important: Tow Capacity Lab provides planning math, not a certification that a combination is safe, legal or manufacturer-approved. The lowest applicable rating always controls.
Frequently asked questions
Can I determine trailer GVWR by adding axle ratings?
Not reliably. GVWR is assigned by the trailer manufacturer and depends on the complete design, not only the sum of axle ratings.
Why subtract tongue weight from axle load?
Part of the trailer's total weight is carried by the tow vehicle through the hitch, so the trailer axle group carries the remainder.
