CAT Scale Tongue Weight Calculator (2-Pass Math)
Enter the axle weights from your certified highway truck-stop CAT scale tickets. This calculator uses 2-pass subtraction moments to isolate exact Tongue Weight, Gross Trailer Weight, and SAE J2807 Percentage.
Pass 1 weighs your truck and trailer connected. Pass 2 weighs your truck alone. The difference in total truck weight between the two passes is your exact tongue weight resting on the hitch ball.
2-Pass Weighing vs. 3-Pass WDH Tuning: What’s the Difference?
Confusion often arises between finding tongue weight versus setting up a Weight Distribution Hitch (WDH):
- 2-Pass Weighing (This Calculator): Specifically designed to find **Tongue Weight** and Gross Trailer Weight. Pass 1 is the combination hitched together; Pass 2 is the tow vehicle by itself. Subtracting truck solo weight from the hitched truck weight isolates the tongue force.
- 3-Pass Weighing (WDH Tuning Only): Used when verifying spring bar tension. Pass 1 is truck + trailer with spring bars tensioned; Pass 2 is truck + trailer with spring bars unhooked; Pass 3 is truck solo. Comparing front steer axle loads across all 3 tickets confirms whether the hitch restores 50% to 100% of front axle weight under vehicle manufacturer specifications (FALR - Front Axle Load Restoration).
Frequently Asked Questions About CAT Scales
How much does it cost to weigh on a CAT scale?
Initial weigh tickets typically cost between $12.50 and $15.00. Each subsequent "reweigh" within 24 hours costs only $2.50 to $3.50. You can pay inside the truck stop fuel desk or through the official Weigh My Truck smartphone app without leaving your cab.
Can standard pickup trucks and campers use commercial CAT scales?
Yes, absolutely. CAT scales are certified legal-for-trade public scales open to anyone. RVers, boaters, and landscapers use them daily. Pull in between commercial 18-wheelers, stop on the yellow lines, and communicate via the intercom box.
Other Towing Verification Tools
Don't have a CAT scale nearby? Use our 2x4 Bathroom Scale Method, verify your payload headroom with the Payload Capacity Calculator, or review the SAE J2807 Percentage Matrix.