Start with the legal reference point, not a guess
First identify the provision that applies to the state, time of travel and question you are checking. Measure in a straight line from that provision's named origin to the extreme rear of the load. The origin for a visibility marker can differ from the origin for a maximum rear projection in the same state.
An open tailgate or hitch-mounted extender can add physical support, but it does not automatically become the legal rear of the vehicle. Keep physical support and legal projection as two separate entries.
Six points that are easy to confuse
Vehicle rear means the legally relevant rear extremity under the provision and should not be replaced with a convenient nearby part without verification. Bed or body is the rear of the load-carrying structure named by a rule. Taillamps are the lights specifically named by California's marker provision. The last point of support is where the load's support ends for California's wheelbase comparison. The center of the last axle is Washington's origin for its separate 15-foot maximum. Physical support is the bed, open tailgate and any entered support surface used by the calculator.
A repeatable measurement workflow
Load the cargo in the position you intend to use, on level ground and without relying on an estimated bed specification. Measure the actual support surfaces and cargo length, then take the separate legal projection from the official reference point. Recheck after straps are tensioned or the load position changes.
- Record bed support, added support and cargo length for physical geometry.
- Record legal rear projection from the state-defined origin.
- Run daylight and nighttime checks separately if the trip can extend after dark.
- Manually verify wheelbase, last axle, total length, special cargo, route and permit conditions.
One endpoint, two correct distances
Imagine the load ends 66 in behind a marked reference line. The last physical support is 24 in behind that line. The load extends 42 in beyond the support, but 66 in beyond the original line. Both measurements are correct; they answer different questions.
Write the origin beside each number: 66 in from the named reference point, and 42 in beyond the last support. Do not copy the physical result into the legal-projection field unless a direct measurement confirms they match.
| Recorded length | Feet | Inches |
|---|---|---|
| 66 in | 5 | 6 |
| 42 in | 3 | 6 |
| 48 in | 4 | 0 |
| 49 in | 4 | 1 |
Keep a measurement record beside the truck
Label a few measurements before selecting equipment. Measure rearward projection along the vehicle, not around the curve of a hull. When the legal origin is unclear for your vehicle, identify it in the official provision or obtain authoritative guidance before entering a confident number.
- Record the cargo's actual position: straight or angled, front-aligned or offset, and each support contact.
- Write bed-floor length and the extra reach behind the floor separately. Do not count the open tailgate twice.
- Record the marker origin, state, travel time and distance from that origin to the load endpoint.
- Record any separate maximum origin: last support and wheelbase in California, vehicle rear for Texas, or last axle in Washington.
- Check the widest load points as well as the rear. Rear-only results do not evaluate a side-projection rule.
- Re-measure after changing supports, tightening the load into position or moving the cargo.
Four state rules, side by side
| State | Measure from | Daylight | After dark | Maximum / other limit |
|---|---|---|---|---|
| California → | Marker: taillamps. Maximum: last point of support plus a wheelbase comparison. | At 4 ft or more behind the taillamps: covered flag or cloth requirement. | At 4 ft or more behind the taillamps: covered red-light requirement. | Projection beyond the last point of support generally cannot exceed two-thirds of wheelbase. |
| Texas → | Maximum/day flag: vehicle rear. Night equipment: rear of bed or body. | More than 4 ft beyond the vehicle rear triggers the covered flag wording. | At least 4 ft beyond the bed or body triggers the covered equipment wording. | The standard rear maximum is measured beyond the vehicle rear; exceptions and permits require review. |
| North Carolina → | Rear of the bed or body for the covered marker and 14-ft provisions. | More than 4 ft beyond the bed or body triggers the covered flag wording. | The same more-than-4-ft origin is used for the covered light wording. | Generally 14 ft beyond the bed or body, subject to named exceptions. |
| Washington → | Day flag: vehicle rear. Night equipment: bed or body. Maximum: center of last axle. | More than 4 ft beyond the rear triggers the covered flag wording. | At 4 ft or more beyond the bed or body triggers the covered equipment wording. | 15 ft beyond the center of the last axle, subject to the statute's exception. |
Checks that still need human review
- The exact vehicle-rear definition for the setup
- Wheelbase and center of last axle
- Overall vehicle-and-load length
- Vehicle, cargo, route and permit exceptions
CHECK YOUR NUMBERS
Turn the measurements into a state-specific review.
Enter the physical support length and the state-defined legal projection separately. The result keeps marker rules, projection limits and manual checks distinct.
Enter my measurements →Continue planning the load
Read the covered state rules
Frequently asked questions
Do I measure overhang from the open tailgate?
Not unless the applicable provision makes that the relevant point. An open tailgate adds physical support, while the legal rule may measure from the vehicle rear, bed or body, taillamps, last support point or axle.
Does a bed extender reduce legal overhang?
It can reduce unsupported cargo length, but do not assume it changes a state's legal reference point. Confirm the exact rule, the extender's rated use and the vehicle manufacturer's limits.
Is unsupported length the same as legal rear projection?
No. Unsupported length is cargo beyond the entered physical support. Legal rear projection is the distance from the reference point named by the applicable state provision to the end of the load.
Should I round 4 ft 1 in down to 4 ft?
No. A one-inch difference can cross a more-than-four-feet threshold. Enter whole feet and remaining inches from your measurement, and re-measure if the load is close to a boundary.
OFFICIAL SOURCES
Rule information was last checked on Sep 8, 2026. Official pages control if this guide and the current law differ.
California Vehicle Code § 24604 · flags and lights ↗California Vehicle Code § 35410 · rear projection ↗Texas DPS · Extended Loads ↗Texas Transportation Code § 621.206 ↗Texas Transportation Code § 547.382 ↗Texas Transportation Code § 547.302 · lighting times ↗N.C. General Statutes § 20-117 ↗N.C. General Statutes § 20-116 · dimensions and loading ↗Washington RCW 46.37.140 ↗Washington RCW 46.44.034 ↗Washington RCW 46.37.020 · lighting times ↗