CAT Scale Tongue Weight Calculator
Use three consistent scale weighings to calculate loaded trailer weight, tongue weight and weight-distribution performance.
WDH engaged
Weigh the combination as you normally tow.
WDH disengaged
Keep passengers, fuel and cargo unchanged.
Truck only
Same truck load, trailer disconnected.
How to use the CAT Scale calculator
- Load the rig the way you travel. Fill the truck with the people, fuel and gear you'll have on the trip, and load the trailer the same way. Everything stays put for all three weighs.
- Weigh 1: hitched, with the weight-distribution hitch engaged. Pull on with the truck's front axle on the first platform (steer), the rear axle on the second (drive) and the trailer axles on the third (trailer). Copy those three numbers from the ticket into Weigh 1.
- Weigh 2: hitched, with the hitch disengaged. Pull off, release the spring bars, then drive back on in the same positions. CAT's reweigh price applies to a return trip on the same scale within 24 hours. Enter steer, drive and trailer.
- Weigh 3: truck only. Unhitch nearby, then weigh the truck by itself with the same people and gear aboard. Enter steer and drive. Ask the cashier if this weigh counts as a reweigh.
- Calculate. TowAtlas works out loaded trailer weight, tongue weight, tongue percentage and how much front-axle weight the hitch restored.
If you have no weight-distribution hitch, Weigh 1 and Weigh 2 are the same. Weigh once hitched, enter that ticket in both rows, and ignore the restoration line.
Reading a 3-platform scale ticket
A CAT ticket lists a weight for each platform, then a gross weight.
- Steer axle is the platform under your truck's front wheels. For a pickup, that's the front axle.
- Drive axle is under the truck's rear wheels, where most tongue or pin weight ends up.
- Trailer axle is under the trailer's wheels, whether it has one axle or three.
- Gross weight is all three platforms added together.
The labels come from semi trucks, but the layout works the same for a pickup and travel trailer. The gross line alone doesn't tell you tongue weight. You need the truck-only ticket to see how much weight the trailer added to the truck's axles.
Example: three tickets from one trip
Example numbersThis is a made-up ticket set for a hypothetical truck and trailer. Your ticket layout comes from CAT, so match its lines to these fields.
A couple weighs their half-ton and travel trailer on the way out of town. They do all three weighs at one truck stop in about 20 minutes, without moving anyone or adding fuel between weighs.
| Ticket | Steer | Drive | Trailer | Gross |
|---|---|---|---|---|
| Weigh 1: WDH engaged | 3,840 lb | 4,060 lb | 6,200 lb | 14,100 lb |
| Weigh 2: WDH disengaged | 3,700 lb | 4,350 lb | 6,050 lb | 14,100 lb |
| Weigh 3: Truck only | 3,900 lb | 3,300 lb | n/a | 7,200 lb |
- Loaded trailer weight: 6,900 lb (14,100 − 7,200)
- Tongue weight: 850 lb (3,700 + 4,350 = 8,050, minus 7,200)
- Tongue percentage: 12.3% (850 ÷ 6,900), inside the 10–15% general guidance for travel trailers
- Front axle load lost, WDH off: 200 lb (3,900 − 3,700)
- Front axle restored by WDH: 140 lb (3,840 − 3,700)
- Front axle restoration: 70% (140 ÷ 200)
The two hitched grosses match, which tells you nothing moved between weighs. The calculator rejects a pair that differs by more than 60 lb.
▶ Try these numbers: Weigh 1 steer 3840, drive 4060, trailer 6200 · Weigh 2 steer 3700, drive 4350, trailer 6050 · Weigh 3 steer 3900, drive 3300.
Next, take the 6,900 lb trailer weight and 850 lb tongue weight to Rig Check to compare them with your truck's payload, axle and hitch ratings.
CAT Scale mistakes that throw off the math
Moving the truck differently between weighs.
If the truck's rear wheels end up on the trailer platform in one weigh, the axle split is wrong. Pull on the same way each time, with each axle group centered on its own platform.
Changing the load between weighs.
A passenger who gets out for the truck-only weigh, a top-off at the pump or a drained tank all change the numbers. The difference shows up as fake tongue weight or a bad trailer weight. Keep everything the same for all three.
Reading the gross line as tongue weight.
The gross weight is the whole truck and trailer. Tongue weight is how much the truck's steer and drive axles gain when you hitch up with the bars off. You need Weigh 2 and Weigh 3 to work it out.
Doing only one weigh.
A single hitched ticket gives you axle weights for that moment, but it can't separate trailer weight, tongue weight and hitch adjustment. Do all three, and use the reweigh price to keep the cost down.
Weighing before you load.
An empty trip to the scale tells you little about the weekend you're planning. Weigh when the rig is packed the way you actually travel.
CAT Scale FAQ
How much does it cost to weigh at a CAT Scale?
CAT Scale lists $15.25 for a first weigh at U.S. locations and $5.25 for a reweigh, according to its own FAQ when we checked in November 2026. That means a three-weigh session can cost $25.75 if both later weighs qualify as reweighs. Prices can change and California certificates cost more, so check at the fuel desk before you pull on.
How does the CAT reweigh discount work?
CAT's published policy says a reweigh qualifies when it's the same vehicle, on the same scale, within 24 hours, and you show the full-price ticket so its number goes on the reweigh. The policy describes the same truck and trailer. Ask the cashier before your truck-only weigh whether it counts as a reweigh or a full-price weigh.
Do I need an appointment or a CDL to use a CAT Scale?
No. CAT says no appointment is necessary. Pull onto the scale, press the intercom button and give the cashier your details. Then pull off, park and go inside for your ticket. CAT's free Weigh My Truck app lets you pay and get the ticket on your phone at many locations, so you don't have to go inside.
How do I read the steer, drive and trailer numbers on my ticket?
Steer is your truck's front axle, drive is its rear axle and trailer is the trailer's axles combined. Gross is all three added together. Copy each platform's number into the matching field for that weigh. For a truck-only weigh, the trailer line is blank or zero, so you only enter steer and drive.
How accurate is a CAT Scale?
Accurate enough to plan with. CAT says every scale is certified in its state, and it backs its tickets with a published guarantee against overweight fines. For RV owners, the bigger risk is changing the load between weighs. If your two hitched grosses are more than about 60 lb apart, weigh again.
What does front-axle restoration mean?
It's how much of the weight the trailer lifted off your front axle that the weight-distribution hitch puts back. If hitching up drops the front axle 200 lb and engaging the bars puts back 140 lb, that's 70%. Your truck's owner's manual and the hitch's instructions give the target for your setup, so compare your result with those.
Can I use a different truck scale instead of a CAT Scale?
Yes. Any certified scale with separate platforms for each axle group gives you the same three numbers. Just do all three weighs on the same scale. A single-platform scale also works, but you'll have to pull on and off for each axle group, so it takes more weighs and more care.
Your results come from the scale numbers you enter. Truck ratings in TowAtlas come from manufacturer documents, and the label on your door always wins. How we check our numbers
Verify the rig, then plan an RV-ready route.
Once your loaded weights make sense, RV LIFE Pro can help with RV-specific routing, campgrounds, stops and navigation for the trip ahead.
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