DOT Weight Limits Per Axle Calculator
Free ToolEnter your route, axle configuration, and per-axle weights to check federal bridge formula compliance, per-axle limits by state, overweight permit requirements, and seasonal restrictions, across all 50 states.
Loading weight calculator…
DOT Weight Limits Per Axle — Steer, Single, Tandem, Tridem
Federal per-axle weight limits come from 23 USC §127 and are implemented through 23 CFR Part 658. A truck can pass the 80,000 lb gross check and still be cited if any single axle or axle group is over its own limit, so gross weight and per-axle weight need to be checked separately.
~12,000–13,000 lb (tire-rated)
Steer Axle
Set by tire load rating, not 23 USC §127 directly
The federal single-axle number technically allows 20,000 lb, but tire load ratings bring the practical steer axle limit down well below that on almost every tractor.
20,000 lb
Single Axle
23 USC §127(a)(1)
Applies to any axle not part of a tandem or tridem group, measured at the road contact points.
34,000 lb
Tandem Axle Group
23 USC §127(a)(1)
Two consecutive axles spaced between 40 and 96 inches apart, treated as one group.
42,000 lb
Tridem Axle Group
23 CFR §658.17
Three consecutive axles within a defined spread, common on tri-axle dump trucks and some tank trailers.
Variable by axle span
Federal Bridge Formula B
23 USC §127
W = 500 × (LN/(N-1) + 12N + 36). Can make a group illegal even when it passes the flat per-axle number above.
The Federal Highway Administration (FHWA) publishes the official size and weight tables, including state-by-state grandfather exceptions. FHWA 23 CFR Part 658 guidance
Weight compliance runs alongside driver compliance. Before dispatch, also check your driver's hours of service status and DOT physical validity. A legal load with an illegal driver carries the same dispatch liability as an overweight one.
DOT Weight Limits for Pickup Trucks — What Weight Actually Requires a USDOT Number
This is a different question than the per-axle limits above, and it's worth separating clearly. A pickup truck by itself, even a heavy one, essentially never triggers the axle weight limits on this page. What people searching "DOT weight limits for pickup trucks" usually want to know is the registration threshold: at what combined weight does towing a trailer turn into something USDOT cares about, with or without a commercial driver's license.
10,001 lb
USDOT number required
GVWR or GCWR, interstate commerce
26,001 lb
CDL generally required
GVWR or GCWR (single vehicle or combination)
Any weight
USDOT number and often CDL required regardless of weight
Hazardous materials requiring placards, or 9–15 passengers for hire / 16+ passengers
The common case: a 3/4-ton pickup towing a gooseneck trailer crosses 10,001 lb GCWR easily. If that combination ever crosses a state line for business, a USDOT number is required — no CDL needed unless the combined GVWR/GCWR passes 26,001 lb. Purely personal, non-commercial towing (a camper, a personal boat, moving your own household goods) generally falls outside DOT's commercial vehicle definition regardless of weight.
Once a pickup-and-trailer combination is registered and operating commercially, it falls under the same per-axle and gross weight framework covered on this page. Intrastate-only operations sometimes use different, often lower, state-set thresholds instead of the federal 10,001 lb figure, so confirm the applicable number with the state DOT if the vehicle never leaves the state. 49 CFR §390.5 definitions
The Federal Bridge Formula, and Why the Math Matters More Than the Gross Weight
Most dispatchers know the 80,000 lb gross limit. Fewer know that the Federal Bridge Formula can make a load illegal even under 80,000 lb, and legal at more than 80,000 lb with the right axle spacing. The formula sets the maximum weight allowed for any group of axles based on the distance between them:
Formula B: W = 500 × (LN / (N-1) + 12N + 36)
Maximum weight in pounds for the axle group
Distance in feet between outer axles of the group
Number of axles in the group (minimum 2)
Spreading axles farther apart raises the allowable weight. A 5-axle truck with trailer tandems set 41 feet from the drive tandems reaches the 80,000 lb legal limit. The same truck with tandems at 40 feet is limited to a lower gross, even though nothing else about the load changed. A few worked examples, including dump truck configurations:
| Configuration | Axles (N) | Span (L) | Bridge Formula Limit | Notes |
|---|---|---|---|---|
| 5 axles, 51 ft span (standard 18-wheeler) | 5 | 51 ft | 79,875 lb | Standard configuration that reaches the full 80,000 lb legal gross. |
| 5 axles, 40 ft span (tandems set closer) | 5 | 40 ft | 73,000 lb | Tandems slid closer together cuts the legal gross even though nothing else changed. |
| 3 axles, 20 ft span (tri-axle dump truck) | 3 | 20 ft | 51,000 lb | Typical tri-axle dump configuration; well under the 80,000 lb interstate cap. |
| 4 axles, 28 ft span (quad-axle dump truck) | 4 | 28 ft | 60,666 lb | Adding a fourth axle raises the bridge formula ceiling for the same footprint. |
| 6 axles, 51 ft span (5-axle + pusher) | 6 | 51 ft | 84,600 lb | A pusher axle raises the allowance for the same 51 ft outer span — the configuration Iowa's expanded weight program typically requires. |
Source: Federal Bridge Formula calculations per FHWA Federal Bridge Formula reference publication. Values assume standard axle configurations.
"Bridge Law" by State — the Kingpin-to-Rear-Axle Rule
When drivers search for a "bridge law chart by state," most aren't looking for the Bridge Formula B math above. They mean the kingpin-to-rear-axle spacing rule: the maximum distance a state allows between a trailer's kingpin and its rear axle, or the center of its rear axle group, before a permit is required. It's a length measurement tied to how the trailer's tandems are set, not a weight calculation, and it gets confused with the Bridge Formula constantly because both rules exist to control how weight loads onto a bridge span.
California
40 ft
Measured to the center of the rear axle group. One of the tightest limits in the country.
Alabama
41 ft
Kingpin to center line of the rear axle group on a 53-foot semitrailer.
New York
41–43 ft
Varies by route: 41 feet on some roads, 43 feet on others.
These three states are well-documented examples, not a complete chart. Even published sources disagree on some states' exact numbers, and the distance can differ by road class within a single state. A trailer can be legal on an interstate and out of compliance a mile later on a state route. Start from the trailer manufacturer's kingpin setting plate, then confirm the current distance with the state DOT for any route you're not already running regularly.
Steer Axle Weight Limit by State — Why There Isn't a Simple Chart
Searches for a steer axle limit "by state" usually don't turn up a clean state-by-state table, because the number that actually gets enforced isn't set state by state. The federal single-axle limit of 20,000 lb technically covers the steer axle, but almost no tractor can put that much weight on its steer tires without exceeding their load rating first. Tire load rating, not axle position, is what caps the number in practice.
Alabama's published standard is a common reference point: 600 lb per inch of tire width, which works out to about 13,200 lb on 11-inch tires. That is a tire-rating limit, not a separate state weight law.
States With Different Weight Limits Than Federal Standards
Congress has let several states allow higher weights than federal limits on their own designated routes, not on the Interstate System. A smaller number of states set lower limits than federal standards, and a few states that get searched by name — Texas, Georgia, Wisconsin — mostly just confirm the federal standard rather than deviate from it. Michigan is the state that matters most for carriers running the Midwest, and Iowa's expanded weight program is worth knowing if you run its non-interstate network.
Oklahoma
Higher gross90,000 lb
Highest base gross limit in the US on state highways
Iowa
Higher gross (permit)~90,000 lb
Expanded weight program on non-interstate state highways; requires an annual permit and enough axles to satisfy the Bridge Formula at the higher weight
Kansas
Higher gross85,500 lb
State highway gross limit exceeds federal interstate standard
New Mexico
Higher gross + axles86,400 lb
Also allows single 21,600 and tandem 34,320 lb on NM roads
Florida
Higher tandem44,000 tandem
Florida allows tandem axle groups up to 44,000 lb, 29% above federal
Texas
Highest permit ceiling254,300 lb permit max
Standard 80,000 lb federal limit applies without a permit; Texas issues some of the highest maximum permit weights in the US, billed by the mile
Georgia
Minor axle variance20,340 lb single
Standard federal limits apply; single-axle figure is sometimes listed slightly above 20,000 lb due to a state rounding allowance
Michigan
Lower axle32,000 tandem
Lower than federal — tandem limit is 32,000 and single is 18,000 lb
Maine
Spring restriction17,000 spring
Most aggressive spring restriction — single axle drops to 17,000 lb
Wisconsin
Standard + seasonal80,000 lb
Standard federal limits, but layers on an aggressive spring thaw restriction period (Mar–May)
Michigan trap: A fully legal 34,000 lb tandem load under federal law is 2,000 lb over Michigan's 32,000 lb limit. Carriers running Chicago-to-Detroit routes get cited at Michigan weigh stations for loads that were legal in Illinois, Indiana, and Ohio. Michigan enforces its lower limits actively.
Spring Weight Restrictions by State
During spring thaw, roads that were frozen all winter start thawing from the top while staying frozen underneath, leaving a weak layer that can't support normal axle weights. States respond by temporarily cutting allowable weights, sometimes by more than a third, on secondary and state routes.
Vermont
Mar–MaySingle drops to 18,000 lb
Maine
Mar–MaySingle drops to 17,000 lb
Michigan
Mar–MayAlready lowest in the US; up to 15,000 lb further reduction
Iowa
Feb–MayUp to 12,000 lb reduction
Minnesota
Mar–MayUp to 12,000 lb reduction
Idaho
Feb–MayUp to 12,000 lb reduction
Pennsylvania
Feb–AprUp to 10,000 lb reduction
Wisconsin
Mar–MayUp to 10,000 lb reduction
Oregon
Jan–AprUp to 8,000 lb reduction
Colorado
Mar–MayMountain pass restrictions
Restriction dates and reduction amounts shift year to year with winter severity. Verify current status with each state DOT before dispatching heavy loads from February through May.
How to Get an Overweight Truck Permit
An overweight permit authorizes a vehicle to run above normal weight limits for a specific load, route, and time window. States issue their own permits; there is no federal overweight permit. A route crossing three states while overweight needs three separate permits.
Confirm you need a permit
Run this calculator to see which states require one. A load legal in Texas may be overweight in Oklahoma at the same axle configuration.
Determine permit type
Single-trip permits cover one load and one route. Annual blanket permits cover unlimited trips on pre-approved routes and cost less for repeat lanes.
Apply before departure
Most states want the permit before the truck moves. Same-day permits exist in some states but not all; budget 1 to 3 business days for complex loads.
Check escort requirements
Very overweight or oversize loads may need escort vehicles or law enforcement escort. Requirements vary by state and load dimensions.
Carry the permit in the cab
The original permit needs to be in the vehicle during transport. A photo on a phone isn't legally sufficient in most states.
Stay on the permitted route
Overweight permits are route-specific. Leaving the permitted route, even for fuel, invalidates the permit and can result in a citation.
For multi-state permits, the IFTA clearinghouse and each state's permit system handle the administrative side. The FMCSA carrier registration portal covers carrier-specific guidance for overweight operations, including USDOT number registration for newly-qualifying vehicles.
An overweight vehicle with brake or tire defects faces compounded liability. Use our FMCSA OOS Risk Assessment to check the vehicle will pass a roadside inspection before dispatching any heavy load.
Overweight Fines by State
Fine structures differ across states, and most aren't linear: being 5,000 lb over doesn't cost twice what 2,500 lb over costs in most of them. Fines are assessed at the weigh station, so knowing where the next one is on your route matters as much as knowing the limit — most state DOT sites publish a weigh station location list alongside their permit portal.
| State | Fine Structure | Example: 10,000 lb over | Additional Consequences |
|---|---|---|---|
| California | $0.01–$0.40/lb over (tiered) | ~$2,000–$4,000 | May require offloading before movement |
| Michigan | $0.10/lb over + escalating | ~$1,000–$3,000 | Mandatory court appearance for severe violations |
| Texas | $100 base + $0.05–$0.25/lb | ~$600–$2,600 | May require escort or permit obtained roadside |
| Ohio | $0.05/lb over on state roads | ~$500 | CSA violation, increased inspection frequency |
| Georgia | $0.03–$0.15/lb over | ~$300–$1,500 | Points on carrier safety record |
| Florida | Flat fee $0–$500 + $0.05/lb | ~$500–$1,000 | Must have permit or offload |
A $2,000 fine plus a $500 towing cost if offloading is required plus one lost day of revenue at $1,500 comes to $4,000 total. A multi-state overweight permit for the same load runs $100 to $400. The permit pays for itself the first time it prevents one roadside stop.
Weight violations feed into FMCSA's Vehicle Maintenance BASIC, the same BASIC affected by mechanical defects found at roadside inspections. Check our FMCSA OOS Risk Assessment and Annual DOT Inspection Calculator to manage that exposure together.
About This Calculator
Built by TruckComplianceHQ, a DOT compliance software platform. Federal limits are based on 23 USC §127 and 23 CFR Part 658; DOT-number registration thresholds are based on 49 CFR §390.5. State weight, permit, and kingpin data comes from individual state DOT publications and is checked periodically; verify current limits directly with the state DOT for loads near a limit. State permit costs are estimates and can change without notice. Browse the full free DOT compliance tools library.
State weight, permit, and kingpin data last verified September 6, 2026.
This tool is for pre-dispatch planning. Weight limits on specific bridges, posted roads, or local ordinances can be lower than state-standard limits and aren't reflected here. Route breakdowns use a shortest state-hop path and may not match your exact highway route. Kingpin-to-rear-axle distances vary by road class within a state; the examples above are reference points, not a complete chart. DOT-number and CDL weight thresholds can differ for intrastate-only operations. Verify with the relevant authorities for critical loads.
DOT Weight Limits Per Axle — Frequently Asked Questions
What are the DOT weight limits per axle?
Under 23 USC §127, a single axle is limited to 20,000 pounds and a tandem axle group (two axles spaced 40 to 96 inches apart) is limited to 34,000 pounds on the Interstate Highway System. A tridem axle group is generally limited to 42,000 pounds. These are federal limits; some states allow higher axle weights on state-designated routes, and a few states, Michigan being the main example, set lower axle limits than the federal standard.
What is the maximum weight for a commercial truck on US interstate highways?
The federal maximum gross vehicle weight on the Interstate Highway System is 80,000 pounds under 23 USC §127. Single axles are limited to 20,000 pounds and tandem axle groups to 34,000 pounds, and the full axle configuration must also satisfy the Federal Bridge Formula B. Some states permit higher weights on state routes outside the Interstate System.
What weight requires a USDOT number, and what does that have to do with weight limits?
This is a different question than "what is the axle weight limit," even though the searches often get mixed together. Under 49 CFR §390.5, a vehicle used in interstate commerce generally needs a USDOT number once its gross vehicle weight rating, gross combination weight rating, actual gross weight, or actual combination weight reaches 10,001 pounds. That threshold triggers registration, not a CDL. A commercial driver's license is a separate, higher threshold, generally required at 26,001 pounds GVWR or GCWR, or for vehicles carrying hazardous materials or a certain number of passengers regardless of weight. Intrastate-only rules vary and are often less strict, so check the state's specific cutoff if the vehicle never crosses a state line.
Do pickup trucks have to follow DOT weight limits?
A standalone pickup truck almost never reaches DOT axle weight limits; those limits generally become relevant once a truck and trailer combination reaches 10,001 pounds gross combination weight rating and the operation crosses state lines or otherwise counts as interstate commerce. At that point, USDOT registration applies even without a CDL, and the vehicle becomes subject to the same per-axle and gross weight framework covered on this page, along with basic safety rules like hours of service exemptions for personal-use towing versus for-hire hauling. Below 10,001 pounds GCWR, and for purely personal, non-commercial towing, DOT weight limits generally do not apply.
What is bridge law for trucks?
Drivers use "bridge law" to mean two related but different rules. The first is the Federal Bridge Formula B, which limits how much weight a group of axles can carry based on the distance between them. The second, more commonly what "bridge law by state" refers to, is the kingpin-to-rear-axle spacing rule: the maximum distance a state allows between a trailer's kingpin and its rear axle (or center of the rear axle group) before a permit is required. California sets this at 40 feet, one of the tightest in the country; other states allow more. Both rules exist for the same reason, to control how weight is spread across a bridge span, but they are checked differently and a load can satisfy one while violating the other.
What is the kingpin-to-rear-axle distance limit by state?
It varies by state and sometimes by road class within a state, which is why there is no single national chart that applies everywhere. California requires 40 feet from kingpin to the center of the rear axle on a 53-foot trailer. Many other states allow 41 to 43 feet, and some tie the distance to 23 CFR §658.13(h), the federal standard for operating without a permit on designated highways. Because sources disagree even on well-documented states, and because the same trailer can be legal on an interstate and illegal on a state route a mile away, check the current number with the state DOT or the loads actual route rather than relying on a fixed chart, and use the trailer manufacturer's kingpin setting plate as the starting point for sliding the tandems.
What is the steer axle weight limit?
There is no separate federal number for steer axles; the 20,000 lb single-axle limit technically applies. In practice, steer axles are constrained well below that by the tire load rating, commonly cited as roughly 600 pounds per inch of tire width. An 11-inch-wide steer tire works out to about 13,200 pounds per tire, and most tractors run 12,000 to 13,000 pounds on the steer axle for that reason, not because a state law sets that number directly. Exceeding the tire rating is what gets cited, so the practical limit tracks the tires on the truck, not a lookup table by state.
Which states have different weight limits than federal standards?
States with higher limits include Oklahoma (90,000 lb gross on state highways), Kansas (85,500 lb gross), New Mexico (86,400 lb gross with higher axle limits), Florida (44,000 lb tandem), Alaska (38,000 lb tandem), North Carolina (38,000 lb tandem), and Iowa (up to 90,000 lb gross under its non-interstate expanded weight program for qualifying multi-axle configurations). Michigan has lower limits than federal standards, 18,000 lb single axle and 32,000 lb tandem, the most restrictive in the country. These variations apply on state-designated routes; the federal 80,000 lb gross limit stays fixed on the Interstate System in every state.
What is Iowa's expanded weight limit program?
Iowa allows gross weights above the federal 80,000 lb limit, up to roughly 90,000 lb, on non-interstate state highways for vehicles with enough axles and spacing to satisfy the Bridge Formula at the higher weight, most commonly seen with 6-axle combinations. It does not apply on the Interstate System, where the federal 80,000 lb cap still governs, and it typically requires an annual permit rather than being automatic. Carriers running Iowa's non-interstate network regularly should confirm current axle and permit requirements directly with the Iowa DOT before relying on the higher figure.
Do Texas, Georgia, and Wisconsin have different truck weight limits than federal standards?
On the Interstate System, no — Texas, Georgia, and Wisconsin all use the standard federal 80,000 lb gross, 20,000 lb single-axle, and 34,000 lb tandem-axle limits. Texas is notable mainly for its permit system: it allows some of the highest maximum permitted weights in the country (up to roughly 254,300 lb for qualifying superloads) and charges permit fees by the mile rather than a flat rate. Georgia's single-axle figure is sometimes listed slightly above the federal number (around 20,340 lb) due to a state-specific rounding allowance. Wisconsin follows the federal standard closely but layers on an aggressive spring thaw restriction period.
What is the weight limit for a tri-axle or quad-axle dump truck?
A tri-axle (tridem) group is generally limited to 42,000 lb federally, and a quad-axle group to around 50,000 lb, though the exact number depends on axle spacing under the Bridge Formula and on the state. A typical tri-axle dump truck with a 20-foot axle spread comes out to roughly 56,000 lb gross under the bridge formula, well under the 80,000 lb interstate cap, which is why tri-axle dump trucks rarely hit the federal gross limit before they hit their tridem group limit or their practical payload capacity.
How much does an overweight truck permit cost?
Costs vary by state, load weight, and route. Missouri ($6 to $150), Arkansas ($5 to $150), Mississippi ($5 to $100), and Oklahoma ($15 to $300) are among the least expensive. California ($16 to $1,500+) and Alaska ($30 to $400+) tend to run highest. Texas uses a mileage-based fee starting around $7 per mile. Annual blanket permits usually cost less over time than repeated single-trip permits for carriers running the same lane.
What happens if a truck is caught overweight at a weigh station?
Most states fine by the pound over the limit, typically $0.05 to $0.20 per pound, so a truck 10,000 lb over can face a $500 to $2,000 fine. The vehicle may also be placed out of service until the excess weight is offloaded or a permit is obtained. The violation shows up in FMCSA's Vehicle Maintenance BASIC and affects the carrier's CSA score for 24 months.
Complete Pre-Dispatch Compliance Toolkit