Axle & centre-of-gravity compliance
Know your load is legal before the truck rolls.
Check axle weights, the Federal Bridge Formula and per-state limits on every load — and get the exact tandem slide when you're over. Built for dispatchers, 3PLs and carriers.
Free · no card · one overweight fine can cost $1,000–$10,000+
Free axle weight US compliance calculator
Enter your scale-ticket weights. We check federal single-axle, tandem-axle and gross weight limits plus the exact bridge formula — instantly, in your browser, no signup.
Imperial (lb / ft) · USD pricing
Federal limits: single 20,000 · tandem 34,000 · gross 80,000 · Bridge Formula W = 500(LN/(N−1) + 12N + 36).
Want axle weights before you load, the slide-to-legal fix, state limits or an API? → that's the platform.
From cargo to verdict in three steps
Describe the load
Pack a container of boxes in 3D — or enter the trailer geometry and weights directly.
Get the verdict
Per-axle-group loads, centre of gravity, gross weight and the bridge formula — federal and state rules — legal or not.
Make it legal
Overweight? We compute the exact number of holes to slide your tandems. No guesswork at the scale.
Everything you need to stay legal
True axle + CoG compliance
Not just gross weight — real per-axle-group loads solved from the load's centre of gravity.
Federal Bridge Formula
The exact formula on every axle group — the check most loads fail even when gross weight passes.
“Make it legal” solver
The precise tandem slide, in holes and inches, that brings every group within limits.
3D load packer
Pack boxes into a container and derive total weight + CoG automatically — then check it.
Import from your manifest
Already have a load sheet? Upload an Excel, CSV, Word table or text PDF and we read the box dimensions, weights and quantities straight into the packer — no re-typing. Review, then pack.
US & Canada
US Federal Bridge Formula plus verified states (TX, CA incl. 40-ft kingpin, FL, IL, PA), and Canada: interprovincial MOU limits in kg with Ontario, Quebec, Alberta & BC rules — one API for both countries.
Compliance certificates
Every check becomes a branded PDF certificate with a QR code anyone can scan to verify it's authentic. Email it to the driver, broker or shipper in one click.
Your trucks, your numbers
Save trailer profiles — axle positions, tares, slider geometry — so every verdict is computed on your rig, not a generic one. Plus reusable load templates.
API-first
One endpoint returns the verdict. Hosted docs, live + test keys, request logs and webhooks — drop compliance into your TMS, ERP or load board.
White-label
Your brand, colours and domain. Manage client companies, transfer credits at wholesale and set your own per-load price — resell compliance as a service.
See it in action
Pack the trailer in 3D, then get the axle-by-axle verdict in one click — exactly what your dispatchers see inside LoadLegit.
Also runs per-state and Canadian rules, exports a verifiable PDF certificate, and drops into your TMS via API.
Pay per load. No seats.
Start free, then buy credits as you go. One credit = one compliance check.
Free trial
Starter
Growth
Scale
One avoided fine pays for roughly 2,000–20,000 checks.
Dispatchers & 3PLs: resell it as your own
Offer weight compliance to every carrier you dispatch — under your brand, your domain, your pricing. Manage all your client companies from one dashboard, or embed the API straight into your TMS.
- ✔ Your logo, accent colour and custom domain
- ✔ One dashboard for all your client companies
- ✔ Per-load pricing you set and mark up
- ✔ API for TMS / ERP / load-board integration
Truck weight limits, explained
What is the Federal Bridge Formula?
The Federal Bridge Formula (23 CFR 658.17) limits how much weight any group of axles may carry based on how far apart they are: W = 500(LN/(N−1) + 12N + 36), where L is the spacing in feet and N the number of axles. A truck can be under 80,000 lb gross and still be illegal on the bridge formula — which is why our calculator checks it explicitly.
What are the federal axle weight limits for trucks?
On the Interstate: 20,000 lb on a single axle, 34,000 lb on a tandem axle group, and 80,000 lb gross vehicle weight — plus the bridge formula on every axle group. Individual states can set different limits on non-Interstate roads, which the LoadLegit platform tracks per jurisdiction.
How much is an overweight truck fine?
It depends on the state and how far over you are — typically from a few hundred dollars to $10,000+, often assessed per pound over the limit. The out-of-service order, reloading, missed delivery windows and liability exposure usually cost more than the ticket itself. Checking a load costs cents.
How does sliding the trailer tandems change axle weight?
Sliding the tandems moves the trailer's support point relative to the load's centre of gravity: slide back to take weight off the trailer tandems (onto the drives), slide forward for the reverse. Each hole is typically 4–6 inches. LoadLegit computes the exact hole count to make an overweight load legal — no trial and error at the scale.
Do I need to install sensors or onboard scales?
No. Onboard scale systems weigh the truck after it's loaded and need hardware installed and calibrated on every unit. LoadLegit is pure software — it predicts axle weights from the load plan before anything is loaded, works on any truck in your fleet instantly, and costs per load instead of per vehicle.
Can I prove a load was checked?
Yes — every check produces a branded PDF compliance certificate with a unique report number and a QR code. Anyone who scans it lands on a verification page confirming the certificate is authentic, what the verdict was, and when it was issued. Email it to drivers, brokers or shippers straight from the app.
Do you check state weight limits, or just federal?
Both. Every check runs the full federal rule set, and we ship verified state rules for Texas, California (including the 40-foot kingpin-to-rear-axle rule), Florida, Illinois and Pennsylvania — with more states being verified. We also publish free reference guides for all 50 states.
Do you support Canada?
Yes. LoadLegit checks Canadian loads against the interprovincial MOU limits in kilograms — steer 5,500 kg, tandem 17,000 kg, tridem 21,000–24,000 kg by spread, gross to 46,500 kg for a six-axle tridem — with province rules for Ontario, Quebec, Alberta and British Columbia. Canada has no federal bridge formula; axle-group limits and spacing govern instead. Work in metric or imperial, and one API covers both countries. See our province guides.
Is this axle weight calculator free?
Yes. The on-page federal calculator is free with no signup. The paid platform adds axle-load prediction from load placement (before you load), the slide-to-legal fix, per-state limits, a 3D load packer, an API for your TMS, and white-label for dispatch agencies — with 25 free checks to start.
Stop guessing. Start knowing.
Your first 25 compliance checks are free.