Steer, drives, trailer in. Holes and notches out.

Type the three weights from your scale ticket. AxleSet tells you exactly how many holes to slide the tandems and how many fifth-wheel notches to move — for your trailer, in your state, with no signal needed.

STEER	11,500
DRIVES	35,000
TRAILER	32,000
GROSS	78,500

Slide tandems 3 holes forward → Steer 11,370 · Drives 33,883 · Trailer 33,247 ✓

Worked by the app for a typical 53-ft van (6-inch holes, tandems at 40 ft). Your trailer gives its own number.

Free to useAxleSet Pro: 7-day free trial Works offlineNo data collected English · Español · Français · Русский · ਪੰਜਾਬੀ

Free, and what AxleSet Pro adds. Free, with no counter and no account: the whole calculation against the federal limits — bridge formula, tandem and fifth-wheel slide, the advice in full — plus your rig with its calibration, how it works and the scale directory. The free card never says just "legal": it says you are within the federal limits and that your state can be stricter. AxleSet Pro opens your state — all 50 and the District of Columbia with their citation, the kingpin and APU rules, the road classes — plus the saved-ticket file and scale correction. It is a subscription: US$6.99 a month or US$39.99 a year, with a 7-day free trial. It renews on its own until you cancel it in your Apple account settings, and a Restore button brings it back on a new phone. If you bought the earlier one-time unlock, you keep it.

No bars at the scale house? It still works. The state limits, the fine schedules and the CAT Scale list are inside the app, not on a server — nothing to load, no ad to wait for. AxleSet does not save you the weigh. It saves you the reweigh.

And the reweigh is the cheap part. Of the 167,118 weight citations written in 2025, 89,883 were on an axle and 27,331 on gross — 3.3 axle tickets for every one on gross. What gets written up is the spread, not the total, and the spread is what sliding fixes.

Not a rule of thumb

"About 400 pounds a hole" is a guess. The real number depends on your trailer: the weight the tandems carry, the hole spacing on the rail, and the kingpin-to-tandem distance. AxleSet takes your rig's measurements once and works every hole and every fifth-wheel notch from the geometry — then shows you what happens at each one, so you can see why the answer is what it is.

The checks the other calculators skip

Federal Bridge Formula (23 CFR 658.17) on every group of consecutive axles, including the 36-foot two-tandem exception everywhere it applies (New Mexico's own bridge law governs there instead). Verified cell by cell against the published table.
Kingpin-to-rear-axle rules — California's 40 feet and the other states that have one, including the ones that measure differently. Some of those statutes tie the rule to the length of the semitrailer; put your trailer's length in the rig profile and AxleSet judges it the way each one writes it: on a trailer the statute never covered it says the rule does not apply, not that you are legal. Where the law makes no distinction by length, it is judged with any trailer.
All 50 states and the District of Columbia: single, tandem, gross, bridge, and the fine schedule, each read on the state's own statute or DOT page — or on an archived copy of that official page — and cited. Every state screen says which one it was and the date it was read; nothing is guessed, and a fine table that is not on an official source is not shown at all. Where a state's own servers stayed shut and the text could only be read on a legal publisher, the state screen says so in as many words.
Interstate vs. state highway where the limits differ — and where a state writes a lower limit for a class of road (a Georgia county road, a Wisconsin Class B road, Kentucky's AA and A, a gravel road in Minnesota), that road class is a choice of its own on the state screen, judged with its own limit and its own citation.
The APU allowance as each law writes it: the federal 550 lb on the Interstate, 400 lb where the state writes that figure, and none at all where its law writes none — and the screen tells you which of the three you are getting.
Two readings, where the law has two. Where a state's own number is lower than the federal rule, or a 1956 grandfather figure has no statute to point to, the verdict uses the number that cannot get you a ticket and shows the other reading beside it, with the rule it comes from.

Built for the scale house

Scan the scale ticket with the camera; the numbers are read on the phone.
Save tickets with the photo, reweigh and compare, export a PDF.
Several rigs saved — switch trailers in one tap, each with its own length.
Straight trucks too, with no trailer: dump, box and mixer.
Tell it whether your drive group carries a lift axle: Alaska writes two bridge formulas and the answer is worth 3,000 lb.
Calibrate the kingpin-to-tandem distance from two weighings, no tape measure.
CAT Scale locations near you, with directions.
Your own target — 60/40, or "drives at 33,500" — on top of fewest moves, balanced, max trailer, max drives.
Pounds or kilograms, for a ticket printed in metric — the limits AxleSet judges by are the United States ones, for all 50 states and the District of Columbia.
Scanned numbers are shown to you before they are used.
Export your tickets as CSV for the dispatcher.
Every state screen shows its source and the date the rules were checked.
Dark mode for the night shift. Big numbers, big buttons.

Coming to the App Store for iPhone. Questions or a number you think is wrong? See the support page.

AxleSet is a reference and a calculator, not legal advice. Laws change, permits change things, and the officer's table wins at the roadside. CAT Scale is a trademark of its owner; AxleSet is not affiliated with CAT Scale Company. Scale locations © OpenStreetMap contributors (ODbL).