Trailer Weight Calculator 🚛
Calculate total trailer weight, tongue weight, and check if your tow vehicle can safely tow your boat. Includes safety margin check.
How to Use the Trailer Weight Calculator
Enter boat dry weight, trailer weight, and gear/fuel weight to calculate total weight and tongue weight.
Tongue weight is approximately 12% of total weight. Never exceed your tow vehicle's maximum towing capacity.
Always check tire pressure, lights, and brakes before towing. Safety first.
Boat & Marine Calculator - Introduction
Add up boat, trailer, fuel, and gear into one number you can compare against your tow vehicle's rating, then estimate tongue weight so you know how much the hitch will load the rear axle. The check prevents the two most common towing mistakes: exceeding the tow rating, and rigging tongue weight outside the safe 10–15% band that causes sway at highway speed.
How It Works
Total trailer weight = boat dry weight + trailer weight + fuel + gear. Tongue weight is estimated at 12% of total — the midpoint of the recommended 10–15% range. The tool then compares total to your vehicle's tow rating and flags anything within 80% (safe), 80–100% (close to limit), or over 100% (do not tow).
Usage Scenarios
- Pre-trip rig check: 3,200 lb boat + 850 lb trailer + 180 lb of fuel + 250 lb of gear = 4,480 lb total. Tongue weight ≈ 538 lb, which fits a Class III hitch (max 800 lb tongue) and lands at 75% of a 6,000 lb-rated SUV's capacity.
- Spotting an undersized tow vehicle: A 4,500 lb sedan rated to tow 3,500 lb cannot legally pull a 4,480 lb rig — the calculator flags 128% of rating. Either rent a larger vehicle for the trip or downsize the boat being towed.
- Re-balancing for highway stability: Same 4,480 lb rig measured at the scale shows only 6% tongue weight (270 lb). Move the spare anchor and battery forward of the axle to bring tongue weight up into the 10–15% range and stop the trailer fishtailing at 60 mph.
Frequently Asked Questions
How do I calculate total trailer weight?
Total trailer weight = Boat dry weight + Trailer weight + Gear/fuel weight. Tongue weight should be 10-15% of total trailer weight. For example: 3,000 lb boat + 800 lb trailer + 200 lb gear = 4,000 lb total. Tongue weight = 400-600 lbs.
What is tongue weight and why does it matter?
Tongue weight is the downward force the trailer hitch exerts on the tow vehicle. Too little tongue weight (under 10%) causes trailer sway. Too much (over 15%) overloads the rear axle and reduces front wheel traction. Proper tongue weight is critical for safe towing.
How do I know if my vehicle can tow my boat?
Check your vehicle's tow rating in the owner's manual. Never exceed this rating. Also check the Gross Combined Weight Rating (GCWR) — the maximum weight of vehicle + trailer + cargo. Ensure your hitch, ball, and wiring are rated for the load.
What safety checks should I do before towing?
Before every tow: check tire pressure on trailer and tow vehicle, verify all lights work (brake, turn, running), ensure safety chains are crossed and connected, check that the boat is properly secured with straps, verify the winch strap is attached, and confirm the drain plug is in.
How do I prevent trailer sway?
Trailer sway is caused by improper tongue weight, speed, crosswinds, or passing trucks. Prevention: ensure proper tongue weight (10-15%), use a weight distribution hitch for heavy loads, install a sway control device, maintain proper tire pressure, and never exceed 55 mph when towing.