How to measure your RV for a carport
Two mistakes account for most badly sized RV carports: measuring to the roofline instead of the air conditioner, and measuring the body instead of the footprint. Both take ten minutes to avoid.
You need eight measurements. None require special equipment beyond a tape measure long enough to reach the roof, a level surface to park on, and someone to hold the other end. Take them in the order below, because the first two are the ones that determine whether the structure works at all.
The measurement points
The checklist
| Measure | How | Why it matters | |
|---|---|---|---|
| A | Maximum height | Level ground to the highest point on the roof. Identify that point by eye first — walk the whole vehicle. | Sets the clear opening height. The dimension that causes damage when wrong. |
| B | Roof equipment | Note the tallest single item and what it is. Do not add items together. | Only the tallest item matters. Two A/C units at the same height change nothing. |
| C | Overall length | Furthest forward point to furthest rearward point, on the ground. | Advertised length usually describes the body, not the footprint. |
| D | Hitch or tongue | Front wall to the tip of the coupler or pin box. | Adds several feet on towables and is absent from most spec sheets. |
| E | Rear ladder | Rear wall to the outermost point of the ladder. | Small but real; commonly the thing that touches the back wall. |
| F | Widest body point | Excluding mirrors and the awning. Usually the sidewall or a fender flare. | Base figure for width before any access allowance. |
| G | Slide-out projection | Sidewall to the face of the fully extended slide. Note which sides. | Only needed if you will extend them under the structure. |
| H | Door, steps, awning | How far the steps drop and the awning reaches when deployed. | Determines whether the space beside the vehicle is usable. |
Finding the genuine tallest point
Before you measure anything, walk the full length of the vehicle and look at the roofline from a distance. On a travel trailer the tallest point is usually the air conditioner. On a fifth wheel it is often the raised front cap. On a well-equipped Class A it can be a satellite dome sitting higher than either air conditioner. On a converted van it is whatever the previous owner bolted on.
Why equipment heights are not added together
A common error is to total up the published heights of every roof item. This is wrong: the items sit side by side on the same roof, not stacked on top of one another. A vehicle with two air conditioners and a satellite dome is exactly as tall as the tallest of those three. Summing them produces a structure specification that is a foot or more taller than necessary, and taller structures cost meaningfully more.
Length is a footprint, not a model number
A trailer marketed as a 26-footer describes its box. The coupler projects forward of that box and the ladder projects behind it. The number you need is the distance between the furthest forward point and the furthest rearward point when the vehicle is parked. For one such trailer that might come to something over 29 feet — but that is an illustration of how far a footprint can exceed a model number, not a fixed rule, so measure your own rather than assuming a set number of feet to add.
Measure it on the ground rather than adding published figures together. Published figures disagree with each other and with reality often enough that the tape is faster than the research.
A printable worksheet
Use your browser's print function on this page to produce a clean copy of the checklist to take out to the vehicle. The navigation, diagrams, and calls to action are removed from the printed version so you get the table and nothing else.
What to do with the numbers
Your measurements describe the vehicle. The structure has to be larger than the vehicle in every dimension, by an amount that depends on how you intend to use the space — and larger again at the nominal level, because advertised carport dimensions are measured to the outside of the frame rather than to the usable opening.
Keep the raw measurements written down somewhere permanent. You will be asked for them by every supplier you speak to, and re-measuring because the note went missing is a genuinely annoying way to spend a Saturday.