To get the right size for a new awning, you have to measure your RV awning from the center of one vertical arm to the center of the other arm. Whatever you do, don't just measure the old fabric. It can stretch or shrink over the years, and that will throw off your numbers, leading to the wrong size for a new assembly.
Why an Accurate Awning Measurement Is Non-Negotiable
Before you grab a tape measure, let's talk about why getting this right is so important. When it comes to measuring your RV awning, being off by even an inch can kick off a series of frustrating and expensive problems. This isn't just about looks; it's about the safety and long-term health of your rig.
A "close enough" measurement might seem harmless, but it can lead to real-world headaches. One of the most common issues from an ill-fitting awning is improper fabric tension, which causes rainwater to pool up instead of running off. That extra weight puts a ton of strain on the roller tube and support arms, which can lead to bent hardware or a catastrophic failure in a sudden downpour.
That stress doesn't stop at the awning. It transfers directly to your RV's sidewall, potentially causing costly delamination or even structural damage down the line.
The True Cost of Inaccuracy
Guessing your measurements is a recipe for disaster. Botched DIY installs due to wrong sizing are a common complaint on RV forums, often costing owners hundreds in return shipping fees and project delays. For a deeper dive, check out this helpful RV awning size guide from Carefree of Colorado.
Taking the time to measure correctly is the single most important step in a successful DIY upgrade. It saves you from return shipping costs, installation headaches, and the disappointment of an awning that just doesn't work right.
At the end of the day, an accurate measurement ensures:
- Proper Functionality: The awning will extend and retract smoothly, without binding up or causing unnecessary wear.
- Enhanced Safety: A well-fitted awning is far more stable and less likely to fail when the wind picks up or the rain starts pouring.
- Longevity: Correct tension and hardware alignment prevent the fabric and mechanical parts from wearing out prematurely.
Think of this initial step not as a chore, but as an investment. A few minutes of careful measuring protects your larger investment in a new awning and, more importantly, your RV itself.
Getting Your Toolkit Ready for an Accurate Measurement
Before you even think about climbing a ladder, taking a few minutes to gather the right tools can be the difference between a frustrating chore and a quick, easy job. When I'm getting ready to measure an RV awning, I always grab a few key items first. This isn't just about being efficient; it's about making sure you get the right numbers the first time.
The most important tool in your arsenal is a good, sturdy metal tape measure. Leave those flexible sewing tapes or fabric measures in the house for this one. A metal tape won’t stretch or sag, which is absolutely critical for getting a precise, straight-line measurement across the side of your rig.
You’ll also need a reliable step ladder. Even if you're tall, a ladder gives you a stable platform to safely reach the top of the awning arms and hardware. Trust me, trying to measure while stretching on your tiptoes is a surefire way to get a bad reading—or worse, take a nasty fall.
A Little Prep Work Goes a Long Way
Beyond just grabbing your tools, a bit of prep makes all the difference. Start by parking your RV on the most level ground you can find. An uneven surface can throw off the frame's alignment just enough to skew your final numbers.
Pro Tip: Your smartphone is your best friend here. Before you pull out the tape measure, snap a few clear photos of any part numbers or model tags you see on the roller tube. Get pictures of the hardware connecting the arms to the RV, too. You'll be glad you have these visual references when it’s time to shop for replacements.
Finally, if the awning is working and it's safe to do so, extend it out a foot or two. This simple step gives you a much better view of all the hardware, the mounting points, and the fabric itself. It just makes it easier to see exactly what you're working with.
With these simple items and a few minutes of prep, you’ll have everything you need to confidently measure your RV awning. Getting this foundation right ensures the numbers you jot down are reliable, whether you're ordering new fabric or a complete assembly from a supplier like RVupgrades.com.
Measuring for a Full Awning Assembly Replacement
When it's time to replace the entire awning—fabric, roller tube, and arms—the measuring process is straightforward. Unlike a fabric-only swap, this job boils down to one key dimension used by all manufacturers.
Your main goal is to find the standard "awning size" that manufacturers and retailers use. It’s a single measurement that tells you exactly what to order.
The Center-to-Center Rule
The one measurement that matters for a complete assembly is the distance from the center of one vertical arm to the center of the other. Grab a good metal tape measure (and maybe a friend to hold the other end), and measure this span right on the side of your RV.
This arm-to-arm distance is your awning size. It’s that simple.
So, let's say you measure it out and get 179 inches. Awning assemblies are sold in one-foot increments, so you’ll just need to do a quick conversion. Since there are 12 inches in a foot, that 179 inches comes out to just under 15 feet (179 / 12 = 14.91 feet). In this case, you'd round up and order a 15-foot awning assembly.
Before you start, it's always a good idea to get your tools in order. A little prep saves a lot of hassle.
Having your tape measure, ladder, and phone (for photos!) ready to go makes the job smoother and safer from the get-go.
Understanding Fabric Width vs. Awning Size
Here’s something that trips up a lot of RVers: the awning size you order isn’t the actual width of the fabric you’ll receive. The "arm-to-arm" measurement is a standard industry size, but the fabric itself is always a bit narrower to fit correctly inside the arms.
This table breaks down the difference so you know exactly what to expect.
Standard Awning Size vs Actual Fabric Width
| Ordered Awning Size (Arm-to-Arm) | Typical Fabric Width |
|---|---|
| 12' Awning | 11' 2" |
| 13' Awning | 12' 2" |
| 14' Awning | 13' 2" |
| 15' Awning | 14' 2" |
| 16' Awning | 15' 2" |
| 17' Awning | 16' 2" |
| 18' Awning | 17' 2" |
| 19' Awning | 18' 2" |
| 20' Awning | 19' 2" |
| 21' Awning | 20' 2" |
Remembering this will save you from thinking you received the wrong product when your new fabric arrives. The 10-inch difference is completely normal and by design.
Don't Forget to Check Sidewall Clearance
Before you hit "buy," there's one more crucial check many RVers skip: making sure you have enough vertical space on your RV's sidewall. Your new hardware needs a clear, flat surface to mount, and you have to be positive it won’t run into anything.
Let's say you're ordering a 15-foot awning for your Class C. The top mounting bracket for the arm has to sit a few inches above your entry door. Go measure from the top of the door frame straight up to the roofline. If you only have five inches of clearance, but the new hardware needs six, you’ve got a big problem.
Crucial Takeaway: I can't stress this enough—always check the installation manual for the specific awning brand you're buying before you place the order. It will tell you the exact vertical clearance needed for the mounting brackets and can save you from a very expensive and frustrating mistake.
This is also a good time to learn a bit about different hardware, like the various types of wall mounting brackets and their specific applications.
Look Out for Obstructions
Finally, take a good, hard look at the entire area where the new awning will live. Will the new arms block a cargo door when it's open? Will they cover up an exterior light, a window, or a vent? I’ve seen it happen.
- Windows and Doors: Make sure the vertical arms won’t overlap the frames.
- Lights and Vents: Check that the awning rail or top brackets won't need to be installed right over them.
- Slide-Outs: Double-check that the new awning assembly won’t interfere with your slide-out when it’s extended.
I always recommend snapping a few photos of the area on your phone and jotting down the locations of these features. This quick visual audit confirms that your new awning will not only fit the arm-to-arm measurement but will also play nice with your rig’s existing layout.
If you’re curious about the financial side of this project, you can get a better idea of what to expect by reading our guide on the RV awning replacement cost.
Measuring for Replacement Awning Fabric Only
If your awning arms and roller tube are still in good shape but the fabric has seen better days, you're in luck. A fabric-only replacement is a fantastic, budget-friendly way to refresh your setup.
Unlike measuring for a whole new assembly, this process demands precision. Getting it right is the key to making sure the new fabric fits perfectly into your existing hardware, giving you that ideal tension and a clean, professional look.
The single most important measurement here is the exact width of your current fabric. Pop your awning open, grab a metal tape measure, and get a reading from one finished edge of the fabric straight across to the other. Just be sure not to include the valance that hangs down at the front.
Let's say your tape reads 14 feet and 2 inches. That is the exact number you need to order. You’re not rounding to the nearest foot like you would for a full assembly. Honestly, this is one measurement where accuracy is non-negotiable.
Don't Overlook the Polycords
Beyond the fabric width, there's another tiny detail many people miss: the polycords. These are the thin, flexible vinyl rods sewn into the fabric’s edges. One polycord slides into the channel on your RV's wall (the awning rail), and the other slides into a channel on the roller tube itself.
These little cords come in different diameters, and you absolutely have to make sure your new fabric has the correct size to fit your existing channels. A cord that’s too small can slip out, and one that’s too large just won’t go in at all.
Here’s how to measure them:
- For the most precise measurement, carefully use calipers to check the polycord's diameter.
- No calipers? No problem. A good trick is to use an adjustable wrench. Gently tighten it around the cord, then measure the opening of the wrench with your tape measure.
- I always recommend measuring both the rail-side cord and the roller-tube-side cord. They can sometimes be different sizes.
Pro Tip from the Field: Before you even think about ordering, fully extend your awning and pull out your smartphone. Take clear, close-up photos of any model number tags or stickers you find on the roller tube—they often become visible once the fabric is unrolled. Giving this info to your supplier is a fantastic backup to your manual measurements and helps them double-check for a perfect match.
A Final Confirmation and Quick Check
If you're on the fence about replacing versus repairing, consider that minor damage might be patchable with products like fabric repair tape for awnings. For widespread wear and tear, though, a new canvas is always the best bet.
The good news is that the RV awning market is fairly standardized. Motorhome and travel trailer awning sizes typically fall between 10 to 21 feet, covering the vast majority of rigs on the road today.
Before you finalize your purchase, it’s always wise to explore your options. You can learn more about finding the best RV awning replacement fabric right here: https://news.rvupgradestore.com/best-rv-awning-replacement-fabric/. Our guide will help you pick a material that not only fits perfectly but also stands up to your specific camping style.
Common Measuring Mistakes to Avoid
I've helped countless RVers with their awnings over the years, and I’ve seen a few common slip-ups that can turn a simple upgrade into a major headache. Knowing these pitfalls beforehand is your best defense against ordering the wrong size. Think of this as your final quality check before you click that "buy" button.
The number one mistake I see, without a doubt, is measuring the old fabric when you're ordering a full new assembly. It seems logical, but it will get you the wrong size every single time. Awning fabric stretches from wind, shrinks from sun exposure, and generally gets warped over the years. Your old, weathered fabric is simply not a reliable blueprint for brand-new hardware.
Fabric vs. Assembly Sizing
When you're ordering a complete assembly—that's the arms, roller tube, and fabric all together—the only measurement that matters is the center-of-arm to center-of-arm distance.
For example, a 15-foot awning assembly is designed for mounting points that are 15 feet apart. But the fabric that comes with it will actually be closer to 14 feet 2 inches wide. If you measured your old 14'2" fabric and ordered an assembly based on that number, you'd get a 14-foot kit, which is a full foot too short for your RV.
This distinction is absolutely critical and is the source of most ordering errors I've encountered.
Key Takeaway: For a full assembly, measure arm-to-arm. For fabric only, measure the finished width of your existing fabric. Never, ever mix these two methods.
Another frequent error is measuring along the curve of the roller tube or a saggy piece of fabric. You have to use a taut metal tape measure to get a straight, horizontal line. Any curve or sag will add inches to your measurement, tricking you into ordering a size that's too big for your rig.
Overlooking Obstructions
One of the most cringe-worthy mistakes is forgetting to check for clearance. Before you lock in any measurement, take a step back and look at what’s actually around the awning area on your RV.
- Doors and Windows: Will the new vertical arms block the corner of your entry door or a main window? A good rule of thumb is to make sure you have at least 3-4 inches of clearance between where the arm will be and any door or window frames.
- Lights and Vents: Double-check that the awning rail or top brackets won't land directly on top of an exterior light, speaker, or refrigerator vent. Relocating those components is a much bigger, more expensive job than just measuring correctly from the start.
Confusing a patio awning measurement with one for a slide-out topper is another common slip-up. They're totally different. Slide-out toppers are measured by taking the slide box flange-to-flange distance and adding a few inches. If you use a patio awning technique here, you'll leave your slide-out seals exposed to the elements.
Taking a few extra minutes to double-check these details ensures the numbers you've written down are solid. And if you run into issues with a damaged awning that needs more than just a replacement, our guide on how to fix an RV awning can give you some helpful next steps. Getting your measurements right is the foundation of a successful project.
Your Awning Measurement Questions Answered
Even with the best instructions, you can still end up with a few lingering questions. It happens to everyone. Based on years of helping fellow RVers, I've put together answers to the most common head-scratchers that come up when measuring an awning.
My goal here is to clear up any final confusion so you can place your order with total confidence. Let’s get these sorted out.
My Measurement Is Between Two Standard Sizes What Should I Do
This is probably the number one question I get, and the answer is critical because it changes depending on what you’re buying. Get this wrong, and you’ll be sending something back.
Here’s the simple rule of thumb I’ve always followed:
For a Full Assembly (Hardware + Fabric): You always round up to the next whole foot. If your center-arm-to-center-arm measurement is 14 feet 6 inches, you need to order a 15-foot awning kit. The hardware is designed for these standard lengths, and rounding up ensures it will mount correctly on your rig.
For Fabric Only: Be exact. Do not round your measurement at all. If your existing fabric measures 14 feet 2 inches from edge to edge, that is the exact size you tell your supplier. They will cut it precisely to that dimension.
Does My RV Type Change How I Measure The Awning
The core measuring technique is universal. Whether you have a massive Class A, a travel trailer, or a fifth wheel, the process—center-of-arm to center-of-arm for assemblies and fabric edge-to-edge for replacements—doesn't change.
What does change is the layout of your specific rig. A Class C might have a cab-over bunk that limits your awning length, while a travel trailer might have a window or compartment door right where an awning arm needs to go.
The measuring method stays the same, but the visual check you do beforehand is unique to your RV. Always walk around your rig and look for any obstructions like lights, slide-outs, or vents before you even pull out the tape measure.
How Do I Measure for a Slide-Out Topper Awning
Slide-out toppers are a completely different animal. If you try to measure one like you would a patio awning, you’re guaranteed to get the wrong size, leaving your slide-out seals exposed to the elements. I've seen it happen, and it's an expensive mistake.
To get this right, you need to measure the total width of the slide-out box. Measure from the outermost edge of the trim flange on one side straight across to the outermost edge of the flange on the other side.
Awning manufacturers typically recommend adding 2.5 inches to each side (for a total of 5 inches) to your measurement. That final number is the topper size you need to order. This extra width ensures the fabric fully covers the slide roof and protects the seals from rain, leaves, and other debris.
At RVupgrades.com, we stock thousands of awning parts, fabrics, and full assemblies to get your rig ready for the road. Shop our extensive collection and find the perfect fit for your RV today at https://www.rvupgradestore.com.
