Two instructions on the same measuring sheet point in opposite directions. Measure the width of a window opening three times and write down the narrowest figure, rounding down. Measure the height three times and write down the largest figure, rounding up. Nothing about the window tells you that, and getting inside mount blinds for window blinds right starts with understanding why one number shrinks and the other grows.
This is an independent editorial review. SelectBlinds did not review or approve this article.
SelectBlinds LLC is a United States retailer and the measuring instructions and policy terms quoted here were read from its own pages on the date of writing; the federal cord rule quoted alongside them places duties on whoever makes or imports a custom window covering rather than on the person who installs one, so it describes what has to be built into the product and not what anyone has to do in their own home.
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Use case 1: fitting inside mount blinds for window blinds into a recess that was never square
An inside mount sits the blind inside the window opening, which looks neater and uses the frame as a built-in border. It also means the product has to fit a hole that a builder made, and old openings are rarely square. That is why the seller asks for three width measurements and three height measurements rather than one of each.
SelectBlinds, a custom window treatment retailer founded in 2003 by Rick Steele and registered at 145 S 79th St, Ste 85, Chandler, AZ 85226, publishes the sequence on its own measuring pages. For width it says to “Measure the exact width (left to right) of the inside edge of the window frame in three different places”, then “Write down the narrowest width of the 3 measurements down to the closest 1/8 inch.” For height it says to “Document the largest height out of the 3 measurements” and round the other way. The rounding instruction is explicit in both directions: on a width, “round down to the nearest 1/8 inch”; on a height, round up.
The logic only makes sense once you picture the failure. A blind cut to the widest point of a tapered opening jams. A blind cut to the shortest point of an uneven opening leaves daylight at the sill. Narrowest width, largest height, and the product clears both.
Then there is the part that surprises first-time buyers. The company says plainly: “We will make all the necessary deductions based on the measurements you provide during checkout.” And immediately after: “Do not make your own deductions.” The factory removes a small amount so the blind can move inside the opening, and that amount differs by product. The chart lists examples of half an inch on one range and three quarters of an inch on another. Subtract it yourself and you have subtracted it twice.
- Decide the mount first, because it changes which number matters.
- Measure the width in three places and keep the narrowest.
- Measure the height in three places and keep the largest.
- Round the width down and the height up, to the nearest eighth of an inch.
- Submit those raw figures and let the factory take its own deduction.
Dark rooms: inside mount blinds for bedrooms and the cord the rule reaches first
A bedroom is where people care most about light, and it is also the room where a federal safety rule is most likely to decide what arrives. Custom window coverings are governed by 16 CFR Part 1260, and its requirements section is short and specific: “Each custom window covering shall comply with section 4.3.1 or 4.3.2.5.2, instead of section 4.3.2, of ANSI/WCMA A100.1-2018.”
Read the Commission’s own findings and the reason is not abstract. The rule records that children can strangle if they can reach “a window covering cord that is longer than 8 inches”. The rest of the section is about making sure they cannot: a rigid shroud that covers a cord has to resist being bent out of the way, and the test is blunt about what counts as a failure. “If the cord shroud accessibility test probe can touch any cord, the cord(s) are considered accessible.” A retraction device has to hold the cord back under a small load, and the thing you actually grip may not itself be a cord of any length.
The practical effect on an order is that the lift system is not a style choice on a custom blind in the way it once was. Choosing inside mount blinds for bedrooms narrows the headrail depth you have to work with and the control options at the same time, and the second constraint arrives from the regulation rather than from the catalog.
Nothing you can drill: inside mount blinds for rentals and the surface you do not own
Renters reach for an inside mount for a reason that has nothing to do with looks. The brackets land inside the opening, on the frame, where the holes are small and out of sight. An outside mount puts them on the wall or the trim, which is a larger commitment to someone else’s paintwork.
The depth question decides it. The company’s generic guidance is that “Inside mounts require sufficient window depth for the selected product”, and it sends you to the product’s own page rather than quoting one figure: “Find your window treatment’s minimum mounting surface requirements in the Specifications tab.” The chart gives a sense of the range, with one range needing two inches of depth and another a little over an inch. A rented apartment with shallow aluminum frames can fail the first and pass the second.
Looking at inside mount blinds for rentals is therefore a two-step check rather than a style decision. Measure the depth from the glass to the front edge of the frame, then find a product whose published minimum is smaller than that number. If no product on the shortlist clears it, the answer is an outside mount and a conversation with the landlord, not a smaller blind.
Not enough depth: inside mount blinds for shallow window frames and the fallback
Some openings simply cannot take a headrail. When that happens the seller’s outside-mount instructions change the arithmetic completely, and the change is worth knowing before you give up on the window.
An outside mount needs flat surface to screw into, and the figure is published: “Confirm you have approximately 2 1/2 inches of flat surface to mount the product.” After that the measurements stop shrinking and start growing. On width you take the biggest of three readings and add two inches on each side, which the page states as a “minimal addition to the size of 2 inches on each side or 4 inches total.” On height you take the greatest reading and add two inches at the top and two at the bottom.
So a window that defeats inside mount blinds for shallow window frames is not a lost cause. It is a different order, four inches wider and four inches taller than the hole, mounted on the wall around it. The one thing that does not change is who owns the number.
- Inside mount: narrowest width, largest height, factory takes a deduction.
- Outside mount: largest width plus four inches, largest height plus four inches, no deduction.
- Either way, the figure submitted at checkout is the figure the product is cut to.
- Orders stop being editable fast: “Changes to orders cannot be made after the expiration of the 4-hour review period.”
Side-by-side by situation
| Your situation | What it needs | Where the risk sits |
|---|---|---|
| Deep, reasonably square opening | Inside mount, three readings each way | Rounding the wrong direction |
| Bedroom with children in the house | Inside mount plus a compliant lift system | Control options narrow before style does |
| Rented home, no wall holes allowed | Inside mount, depth checked per product | Frame too shallow for the chosen range |
| Shallow or flush frame | Outside mount, four inches added each way | Not enough flat surface to screw into |
| Measured once, in a hurry | A second trip round the window | A custom cut cannot be returned |
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Frequently Asked Questions
These come up repeatedly on made-to-measure orders, and the answers are all on the seller’s own pages rather than in general advice.
Can I return a custom blind that does not fit?
Not on fit alone. The terms say that “As all of our blinds and shades are custom-made, we cannot offer a refund or exchange unless a product is defective.” A defective product is a separate route, and the free three-year limited warranty covers residential purchases with a flat fifteen dollar return shipping charge.
What does the paid measuring guarantee actually do?
It buys a remake, not a refund. The company states that “Our Measuring Guarantee must be purchased at the time you order for a fee per window covering”, that “you are limited to one (1) remake per covered product from your original order”, and that it “applies only to remakes of a product due to customer error in measurements”. It also notes that “no cash refunds are available through FIT Protection”.
How long do I have if something else goes wrong?
There is a separate satisfaction window: “we promise to resolve the issue at no cost to you for up to 90 days from the date of purchase.” Changing your mind is treated differently from a defect, and shipping is not covered in that case.
Do I subtract anything before submitting my numbers?
No. The instruction is explicit both ways: the factory makes the deductions from the figures you provide, and you are told not to make your own.
Conclusion
The irreversible step in this purchase happens in your hands, with a tape, before any money changes hands. A custom blind is cut to the number you typed, the seller says in writing that it cannot take it back for fit, and it sells insurance against your own ruler as a separate line item. Decide the mount, measure three times each way, round in the two opposite directions the instructions ask for, and let the factory take its own deduction.
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