Commercial Truck Weight Limit Calculator
Free ToolEnter your route, axle configuration, and per-axle weights to instantly check federal bridge formula compliance, identify states with different weight limits, calculate overweight permit requirements, and flag seasonal restrictions — across all 50 states.
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Federal Truck Weight Limits — 23 USC §127 Explained
Federal weight limits for commercial vehicles on the National Highway System are established by 23 USC §127 and implemented through 23 CFR Part 658. These limits have three distinct components that all apply simultaneously — a truck can be legal on gross weight but still illegal on axle weight or the bridge formula:
80,000 lb
Gross Vehicle Weight Limit
23 USC §127(a)(1)
The combined weight of the vehicle and all cargo. This is the most widely known limit but not the only one.
20,000 lb
Single Axle Weight Limit
23 USC §127(a)(1)
The weight carried by any single axle — measured at the road contact points. Applies to each axle individually.
34,000 lb
Tandem Axle Group Limit
23 USC §127(a)(1)
The weight carried by any two consecutive axles spaced between 40 and 96 inches apart.
Variable by axle span
Federal Bridge Formula B
23 USC §127
W = 500 × (LN/(N-1) + 12N + 36). Limits weight concentration over any group of axles to protect bridges and pavement.
The Federal Highway Administration (FHWA) publishes the official size and weight limits tables, including all state-by-state exceptions granted under grandfather provisions. FHWA 23 CFR Part 658 official guidance
Weight compliance is the pre-dispatch check that runs alongside driver compliance. Before dispatching, also verify your driver's hours of service status and DOT physical validity — a legal load with an illegal driver results in the same dispatch liability.
The Federal Bridge Formula — Why the Math Matters More Than the Gross Weight
Most dispatchers know the 80,000 lb gross limit. Far fewer understand that the Federal Bridge Formula can make a load illegal even when gross weight is under 80,000 lb — and legal at over 80,000 lb with the right axle spacing. The formula calculates 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)
The practical implication: spreading axles farther apart increases the allowable weight. A 5-axle truck with trailer tandems slid to 41 feet from the drive tandems achieves the 80,000 lb legal limit. The same truck with tandems at 36 feet is limited to approximately 76,500 lb — even though nothing else changed. Here are worked examples:
| Configuration | Axles (N) | Span (L) | Bridge Formula Limit | Notes |
|---|---|---|---|---|
| 5 axles, 51 ft span | 5 | 51 ft | 79,875 lb | Standard 18-wheeler at maximum legal gross |
| 5 axles, 40 ft span | 5 | 40 ft | 73,000 lb | Tandems closer together — lower legal limit |
| 3 axles, 20 ft span | 3 | 20 ft | 51,000 lb | Tri-axle dump truck — typical configuration |
| 6 axles, 51 ft span | 6 | 51 ft | 84,600 lb | Adding a pusher axle increases bridge formula allowance |
Source: Federal Bridge Formula calculations per FHWA Federal Bridge Formula reference publication. Calculated values assume standard axle configurations.
States With Different Weight Limits Than Federal Standards — The Complete List
Congress has granted several states the right to allow higher weights than federal limits on their state-designated routes (not on the Interstate System). A smaller number of states impose lower limits than federal standards — Michigan being the most consequential example for carriers running the Midwest.
Oklahoma
Higher gross90,000 lb
Highest base gross limit in the US on state highways
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
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
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 regularly get cited at Michigan weigh stations for loads that were legal in Illinois, Indiana, and Ohio. Michigan actively enforces its lower limits and is one of the highest-fine states in the country for axle weight violations.
Spring Weight Restrictions by State — The $10,000 Surprise Most Dispatchers Miss
Spring thaw restrictions are the most expensive surprise in heavy hauling. During spring thaw, roads that were frozen solid all winter begin thawing from the top while remaining frozen below, creating a weak layer that cannot support normal axle weights. States respond by temporarily reducing allowable weights — sometimes by 35% or more — 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 US — additional 15,000 lb reduction possible
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
Seasonal restriction dates and reduction amounts vary year-to-year based on winter severity and spring temperatures. Always verify current restriction status with each state DOT before dispatching heavy loads in February–May. Some states post real-time restriction status on their DOT websites; others require a phone call.
How to Get an Overweight Truck Permit — State-by-State Guide
An overweight permit authorizes a vehicle to operate above normal weight limits for a specific load, route, and time period. Permits are issued by state DOTs — there is no federal overweight permit. If your route crosses three states and you are overweight, you need three separate permits.
Confirm you need a permit
Run this calculator to identify which states require a permit. A load legal in Texas may be overweight in Oklahoma at a specific axle configuration.
Determine permit type
Single-trip permits (one load, one route) vs. annual blanket permits (unlimited trips on pre-approved routes). Annual permits are more cost-effective for repeat lanes.
Apply before departure
Most states require permits before you move. Same-day permits are available in some states but not all. Factor 1–3 business days for complex loads.
Know escort requirements
Extremely overweight or oversize loads may require escort vehicles or law enforcement escort. Requirements vary by state and load dimensions.
Carry the permit in the cab
The original permit must be in the vehicle during transport. A photo on your phone is not legally sufficient in most states.
Follow the permitted route exactly
Overweight permits are route-specific. Deviating from the permitted route — even for fuel — invalidates the permit and can result in citation.
For multi-state permits, the IFTA clearinghouse and state-specific permit systems handle the administrative side. The FMCSA carrier registration portal provides carrier-specific guidance on operating overweight loads.
Overweight operations also require your vehicle to be in excellent mechanical condition — an overweight truck with brake or tire defects faces compounded liability. Use our FMCSA OOS Risk Assessment to verify your vehicle will pass a roadside inspection before dispatching any heavy load.
Overweight Fines by State — What Getting Caught Actually Costs
Overweight fines are calculated differently across states. Most use a per-pound-over structure that makes the cost non-linear — being 5,000 lb over is not twice as expensive as being 2,500 lb over in many states. Here is the real cost picture:
| 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 |
True cost math: A $2,000 overweight fine + $500 towing cost if offloading is required + one day lost revenue ($1,500) = $4,000 total cost. A multi-state overweight permit for the same load costs $100–$400. The permit pays for itself the first time it prevents a single 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 Vehicle Maintenance BASIC exposure holistically.
About This Weight Limit Calculator
Built by TruckComplianceHQ, a DOT compliance software platform. Federal weight limits are based on 23 USC §127 and 23 CFR Part 658. State weight limit data is sourced from individual state DOT publications and is updated periodically — always verify current limits directly with the state DOT for loads near the limit. State permit costs are estimates and may change without notice. Browse our full free DOT compliance tools library.
This tool is for pre-dispatch planning purposes only. Weight limits on specific bridges, posted roads, or local ordinances may be lower than state-standard limits and are not reflected in this calculator. Always verify with relevant authorities for critical loads.
Commercial Truck Weight Limits — Frequently Asked Questions
What is the maximum weight for a commercial truck on US interstate highways?
On the US Interstate Highway System, the federal maximum gross vehicle weight is 80,000 pounds under 23 USC §127. Additionally, single axles are limited to 20,000 pounds, tandem axle groups are limited to 34,000 pounds, and all axle configurations must comply with the Federal Bridge Formula B (W = 500 × (LN/(N-1) + 12N + 36)). Some states have received grandfather rights to permit higher weights on specific routes, and some states allow higher weights on state routes not on the Interstate System.
What is the Federal Bridge Formula and how does it work?
The Federal Bridge Formula B, established under 23 USC §127, determines the maximum weight any group of axles can carry based on the distance between axles. The formula is: W = 500 × (LN/(N-1) + 12N + 36), where W is maximum weight in pounds, L is the distance in feet between the outer axles of the group, and N is the number of axles in the group. The formula exists to protect road surfaces and bridges from being stressed beyond their design capacity. A vehicle can comply with gross weight limits but still violate the bridge formula if the axle spacing concentrates too much weight over a short span.
Which states have different weight limits than federal standards?
Several states have weight limits that differ from federal standards. States with HIGHER limits include: Oklahoma (90,000 lb gross on state highways), Kansas (85,500 lb gross on state highways), New Mexico (86,400 lb gross with higher axle limits), Florida (22,000 single / 44,000 tandem axle limits), Alaska (38,000 tandem axle limit), and North Carolina (38,000 tandem axle limit). States with LOWER limits include: Michigan (18,000 single / 32,000 tandem axle limits — the most restrictive in the US). These variations apply to state-designated routes; federal interstate limits of 80,000 lb gross remain fixed on the Interstate System in all states.
How much does an overweight truck permit cost?
Overweight permit costs vary significantly by state, load weight, and route. Common ranges: Missouri ($6–$150), Arkansas ($5–$150), Mississippi ($5–$100), and Oklahoma ($15–$300) are among the least expensive. California ($16–$1,500+) and Alaska ($30–$400+) tend to be most expensive. Texas uses a mileage-based fee structure starting around $7 per mile. Most states charge flat fees based on the degree of overweight, while others charge per-mile. Multi-trip permits (annual blanket permits for repeat routes) are often more cost-effective for carriers running the same route regularly.
What are spring weight restrictions and which states have them?
Spring weight restrictions (also called spring thaw restrictions or frost laws) are temporary reductions in allowable axle and gross weights applied to roads during the spring thaw period, typically February through May depending on the state. During winter, frozen ground supports heavy loads; when temperatures rise, the ground thaws from the top while remaining frozen below, creating a weak layer that cannot support normal axle weights without severe pavement damage. States with significant spring restriction programs include Maine, Vermont, Michigan, Minnesota, Wisconsin, Iowa, North Dakota, South Dakota, Idaho, Montana, Illinois, Indiana, Ohio, Pennsylvania, New York, and Oregon. Vermont and Maine have some of the most aggressive programs, reducing single axle limits to 17,000–18,000 lb during peak restriction periods.
Do I need an overweight permit for every state on my route?
Yes — overweight permits are issued by individual states and are only valid within that state. If your route crosses multiple states and you are overweight, you need a separate permit from each state you will travel through. There is no single federal overweight permit. Some states participate in permit clearinghouse systems that simplify the application process, but each state still issues its own permit. Permits must typically be in the cab during travel and are tied to specific routes, time windows, and load configurations. Operating overweight without a permit in any state exposes the carrier to fines that can far exceed the permit cost.
What happens if a truck is caught overweight at a weigh station?
Penalties for overweight violations vary by state but are substantial. Most states use a tiered fine structure based on the degree of overweight, typically $0.05–$0.20 per pound over the limit. A truck that is 10,000 pounds overweight could face fines of $500–$2,000 per violation. Beyond the fine, an overweight vehicle may be placed out of service and prohibited from moving until the excess weight is offloaded or a permit is obtained. The violation is recorded in FMCSA's SMS system under the Vehicle Maintenance BASIC, affecting the carrier's CSA score for 24 months. Repeat violations can trigger compliance reviews and increased inspection frequency.
What is the maximum weight for a 5-axle semi-truck (18-wheeler)?
A standard 5-axle tractor-trailer (18-wheeler) can legally carry a maximum gross weight of 80,000 pounds on US Interstate highways under federal law. This breaks down as: steer axle (typically 12,000–13,000 lb), tandem drive axles (up to 34,000 lb combined), and tandem trailer axles (up to 34,000 lb combined). The total of 80,000 lb must also comply with the Federal Bridge Formula, which depends on the distance between axle groups — most standard 5-axle configurations with the trailer tandems set at 41–43 feet from the drive tandems achieve the 80,000 lb maximum. Payload capacity is gross weight minus tare weight, typically 42,000–46,000 lb for a loaded 53-foot dry van.
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