New Hampshire Truck Weight and Size Limits
Legal limits for a truck in New Hampshire without a permit: Interstate axle and gross weights, height, width, and semitrailer length, each with its official source.
New Hampshire limits at a glance
| Limit | New Hampshire | Source |
|---|---|---|
| Interstate gross weight | 80,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Interstate single axle | 20,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Interstate tandem axle | 34,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Width (National Network) | 102 in | 23 CFR 658.15, Width (eCFR) |
| Height | 13 ft 6 in | N.H. RSA 266:10 |
| Semitrailer length | 53 ft; a semitrailer over 48 ft needs 41 ft or less from the kingpin to the rear axle (or tandem midpoint) and a rear underride guard | N.H. RSA 266:11 |
| Grandfathered semitrailer length | 48 ft | 23 CFR part 658, Appendix B, Grandfathered Semitrailer Lengths (eCFR) |
Interstate weight limits
Federal law sets the Interstate limits at 20,000 lb on a single axle, 34,000 lb on a tandem, and 80,000 lb gross, with the bridge formula on every axle group (23 CFR 658.17). States may keep higher limits they had before the federal limits took effect ("grandfather rights").
For trucks over 73,280 lb gross. At 73,280 lb or less, 22,400 lb single and 36,000 lb tandem apply. FHWA also lists a grandfathered 103,000 lb gross.
FHWA on New Hampshire: New Hampshire has a grandfather provision under Federal law (23 U.S.C. §127) to allow vehicles to operate up to 22,400 lbs. on a single axle, 36,000 lbs. on a tandem axle, and 99,000 lbs. GVW on parts of the Interstate system. See the Routes section for a full description of the routes to which this grandfather provision applies.
Bridge formula check with New Hampshire limits
A 5-axle tractor-trailer is filled in. Change the spacings and weights to match your rig; the limits for single axles, tandems, and gross are New Hampshire's Interstate limits.
Your result
New Hampshire limits off the Interstate
FHWA's summary of New Hampshire law for trucks in regular operation (no permit), including non-Interstate highways. It reflects state law as of October 1, 2012; check the state for later changes.
- Single axle
- 20,000 lbs. on Interstate highways when GVW is greater than 73,280 lbs. / 22,400 lbs. on Interstate and non-Interstate highways when GVW is 73,280 lbs. or less (for three-axle single-unit vehicles and all other vehicles with axles 10 ft. or more apart)
- Tandem axle
- 34,000 lbs. on Interstate highways when GVW is greater than 73,280 lbs. / 36,000 lbs. on Interstate and non-Interstate highways when GVW is 73,280 lbs. or less
- Tridem axle
- Per State weight table
- Gross weight
- 80,000; 99,000 on non-Interstate highways*
- Other
- 5 percent tolerance on non-Interstate highways, up to a maximum GVW of 80,000 lbs.
Where New Hampshire allows more than federal limits
- New Hampshire allows the following weight limits in excess of Federal limits on non-interstate highways:
- Single-axle limit of 22,400 lbs.
- Tandem-axle limit of 36,000 lbs.
- Tridem-axle limit of 54,000 lbs.
- Gross vehicle weight limit of 99,000 lbs.
- New Hampshire allows a 5 percent tolerance above GVW limits and axle limits on non-Interstate and General Highway System up to 80,000 lbs. GVW and a 10 percent tolerance above axle weight limits for vehicles with additional registration.
Height, width, and length
- Width: 102 inches. States may not set a width limit of more or less than 102 inches on the National Network (23 CFR 658.15(a)). Permits can allow wider loads.
- Height: 13 ft 6 in. There is no federal height limit; each state sets its own.
- Semitrailer length: 53 ft; a semitrailer over 48 ft needs 41 ft or less from the kingpin to the rear axle (or tandem midpoint) and a rear underride guard
- Grandfathered semitrailer length: 48 ft. The minimum semitrailer length the state must allow in a tractor-semitrailer combination on the National Network, based on lengths legal in the state on December 1, 1982. Federal law also requires at least 48 ft (23 CFR 658.13(b)(1)).
Over these limits you need a permit. New Hampshire oversize/overweight permits (603-271-2691).
New Hampshire compared with neighboring states
| State | Gross | Single | Tandem | Height | Semitrailer |
|---|---|---|---|---|---|
| New Hampshire | 80,000 lb | 20,000 lb | 34,000 lb | 13 ft 6 in | 53 ft |
| Maine | Pending | Pending | Pending | 13 ft 6 in | 48 ft on the Interstate and National N… |
| Massachusetts | 80,000 lb | 22,400 lb | 34,000 lb | 13 ft 6 in | 53 ft |
| Vermont | 80,000 lb | Pending | Pending | 13 ft 6 in | 53 ft on the Interstate and qualifying… |
Sources
Source: FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B · Effective Oct 1, 2012 · Last verified Sep 28, 2026
Source: FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendix A: New Hampshire · Effective Oct 1, 2012 · Last verified Sep 28, 2026
Source: 23 CFR 658.15, Width (eCFR) · Last verified Sep 28, 2026
Source: 23 CFR part 658, Appendix B, Grandfathered Semitrailer Lengths (eCFR) · Last verified Sep 28, 2026
Source: N.H. RSA 266:11 · Last verified Sep 28, 2026
Source: FHWA, Oversize/Overweight Load Permits: State permit contacts · Last verified Sep 28, 2026
Limits change, and cities, counties, and posted bridges can set lower ones. Check with New Hampshire before you run a load near the limits. Page data last verified Sep 28, 2026.