Trailer Tongue Weight Converter
Calculate the proper tongue weight for your trailer based on total weight, using the 10-15% rule for safe towing.
Enter your total loaded trailer weight to calculate the safe tongue weight range.
Understanding Trailer Tongue Weight
Tongue weight is the downward force that the trailer coupler exerts on the hitch ball of the tow vehicle. It is one of the most critical safety factors in towing. Too little tongue weight causes dangerous trailer sway at highway speeds. Too much tongue weight overloads the rear axle of the tow vehicle, reducing steering control and potentially damaging the hitch or vehicle frame.
The 10-15% Rule:
The universally accepted guideline is that tongue weight should be 10-15% of the total loaded trailer weight (also called Gross Trailer Weight or GTW).
Tongue Weight = Total Trailer Weight × Percentage
Minimum: Total Weight × 0.10
Maximum: Total Weight × 0.15
Ideal target: Total Weight × 0.12 (12%)
For example, a trailer with a GTW of 5,000 lbs (2,268 kg):
- Minimum tongue weight: 500 lbs (227 kg)
- Ideal tongue weight: 600 lbs (272 kg)
- Maximum tongue weight: 750 lbs (340 kg)
Why This Range Matters:
- Below 10%: The trailer becomes tail-heavy. This shifts the pivot point and makes the trailer prone to fishtailing (lateral sway). At highway speeds, sway can become uncontrollable and cause a rollover accident.
- 10-15%: The optimal range. The trailer tracks straight, responds predictably to steering inputs, and brakes safely.
- Above 15%: The rear of the tow vehicle is pushed down excessively, lifting the front end. This reduces front-tire traction, making steering sluggish and extending braking distances. It can also exceed the hitch weight rating.
Hitch Class Ratings:
| Hitch Class | Max GTW (lbs) | Max GTW (kg) | Max Tongue (lbs) | Max Tongue (kg) |
|---|---|---|---|---|
| Class I | 2,000 | 907 | 200 | 91 |
| Class II | 3,500 | 1,588 | 525 | 238 |
| Class III | 8,000 | 3,629 | 800 | 363 |
| Class IV | 10,000 | 4,536 | 1,000 | 454 |
| Class V | 17,000 | 7,711 | 1,700 | 771 |
How to Adjust Tongue Weight:
If your tongue weight is too low (below 10%):
- Move heavy cargo forward in the trailer, closer to the axle or slightly ahead of it
- Do not place all heavy items at the rear
If your tongue weight is too high (above 15%):
- Move some heavy items rearward, but not behind the axle
- The heaviest items should be centered over or slightly ahead of the trailer axle
How to Measure Tongue Weight:
- Tongue weight scale: A specialized scale placed under the coupler. Most accurate method. Available at trailer shops for $30-80.
- Bathroom scale method: Place a pipe vertically on a bathroom scale under the coupler. Not perfectly accurate but gives a reasonable estimate for lighter trailers.
- Truck weigh station: Weigh the tow vehicle with and without the trailer connected. The difference is the tongue weight.
Unit Conversions:
- 1 pound = 0.4536 kg
- 1 kg = 2.2046 lbs