How to Measure Motorhome Windows for Blinds | Perfect Fit Method

For the full breakdown, see our best Window Blinds for Motorhome guide.

You can learn how to measure motorhome windows for blinds in about five minutes, but getting it right is the difference between a clean installation and a frustrating return. Unlike house windows, RV windows are rarely perfectly square, so a single measurement in each direction won’t cut it. The method starts with one key decision—inside mount or outside mount—then follows three width and three height measurements per window. House windows are usually square enough that a single measurement works, but RV windows can vary by a quarter inch or more across the same opening, which is why three-point measuring is essential.

Measuring Motorhome Windows for Blinds: Inside Mount vs Outside Mount

An inside mount places the blind inside the window frame for a flush look, while an outside mount covers the full opening plus overlap for maximum light blocking. Before you pick up a tape measure, decide which approach fits your RV because this choice changes how you collect each dimension.

For an inside mount, you measure the window opening itself. Take the width at the top, middle, and bottom of the frame, then use the smallest number so the blind clears the sides. For height, measure the left, center, and right—but which number you use depends on your blind brand. Some manufacturers want the longest height for full coverage from top to bottom; others want the shortest for a snug fit. Always follow the product-specific instructions before placing your order. You also need to check depth clearance for hardware like locks and levers before choosing an inside mount.

For an outside mount, you measure the area you want the blind to cover, including any trim or frame, then add extra width and height for overlap. The exact amount depends on your chosen product, so check the vendor’s instructions as detailed in this RV blind measurement guide.

How Do You Measure an RV Window in Three Steps?

Step 1: Gather the right tools. Use a steel or metal tape measure—fabric sewing tapes can stretch and give inaccurate readings. Have paper and a pen ready, and label each measurement in width-by-height (W x H) format to avoid swapping values when you order. Measure every window separately; they can differ even on the same RV.

Step 2: Take three width and three height measurements per window. For width, measure at the top, middle, and bottom of the opening or coverage area. For height, measure at the left, center, and right. RV windows are often out of square, so three readings catch the variation that a single measurement would miss. Label each measurement clearly on your paper—width readings in one row, height readings in another—so you don’t confuse them when transferring to an order form. For an inside mount, use the smallest width so the blind clears the sides. For height, refer to the specific product’s guidance—some brands use the longest measurement for full coverage, others the shortest for precision. For an outside mount, include the full area you want covered in your three measurement points, then add the recommended overlap.

Step 3: Record precision, recheck, and verify. U.S. blind manufacturers typically require measurements to the nearest ⅛ inch, though some retailers specify exact millimeters. Check the ordering system on your chosen product page before rounding. Always measure the window frame or opening itself, not the old blind—old blinds can be warped, shrunken, or undersized. Take a second set of measurements, and if the two sets differ, take a third and use the median value. This extra step catches recording errors before they become a return.

Before finalizing an inside-mount order, check the opening depth for hardware obstructions. Locks, levers, and window cranks can reduce usable space—most blinds need at least 30 mm of clearance on the sides and 45 mm at the top and bottom. If hardware makes an inside mount tight, browse our recommended window blinds for motorhomes to find outside-mount options that solve the problem cleanly.

FAQs

Should I measure the old blind or the window opening?

Always measure the window opening or frame, not the old blind. Existing blinds can be warped, shrunken, or poorly fitted, so they won’t give you accurate dimensions for a replacement that needs to fit the actual opening.

What happens if I only measure once instead of at three points?

RV windows are rarely perfectly square, so a single measurement risks ordering a blind that’s too tight on one side or leaves a gap. Taking width and height at three points each catches the variation and ensures your blind fits the real opening, not an idealized version of it.

How much overlap should I add for an outside mount?

Check the specific product’s instructions, and when in doubt, lean toward more overlap for privacy and light control.