Example data
| Scenario | Recess Depth | Obstruction | Style | Goal | Available Depth | Required Depth | Pass | Spacer Needed |
|---|---|---|---|---|---|---|---|---|
| Kitchen herb window | 3.00 in | 0.50 in | Roller Shade | Minimum | 2.50 in | 2.125 in | Yes | 0.00 in |
| Greenhouse vent handle | 2.50 in | 0.75 in | Cellular Shade | Flush | 1.75 in | 3.000 in | No | 1.250 in |
| Shed window crank | 90 mm | 20 mm | Faux Wood Blind | Minimum | 70 mm | 71.1 mm | No | 1.1 mm |
Examples are illustrative. Always confirm manufacturer depth specs.
Formula used
- Available Depth = Recess Depth − Obstruction Projection.
- Base Required Depth = Preset depth for selected style and goal, or Custom Required Depth.
- Hardware Required Depth = max(Bracket/Cassette Depth, Base Required Depth).
- Total Required Depth = Hardware Required Depth + Add-on Depth + Mechanism Allowance + Safety Allowance.
- Spacer Needed = max(0, Total Required Depth − Available Depth).
- Recommended Order Width = Opening Width − 2 × Side Clearance (each). Recommended Order Height = Opening Height − Top Clearance − Bottom Clearance.
How to use this calculator
- Measure opening width and height at three points. Use the smallest values.
- Measure recess depth from the front edge to the back wall.
- Measure any obstruction projection, like a window crank or handle.
- Pick a style and mount goal. Enter bracket depth if you have it.
- Add allowances for add-ons, mechanisms, and measuring tolerance.
- Press Calculate to see pass/fail, spacer needs, and order size.
Practical clearance planning
Inside mounting looks clean, but it only works when the recess can accept the full depth of the headrail, brackets, and any add‑ons. This calculator converts your measurements into an “available depth” figure, then compares it to a “required depth” that includes allowances for hardware and tolerance. The pass/fail result is a fast screening step before you order.
Measuring the opening correctly
For width and height, measure in three places and record the smallest value. Garden structures often shift with humidity, so also note seasonal movement around greenhouse frames and shed windows. Enter side, top, and bottom clearances to prevent rubbing against paint, seals, or rough timber. The recommended order size reflects those deductions.
Depth, obstructions, and real-world risk
Depth is the limiting factor for inside mounts. Measure from the front edge of the trim to the back wall, then subtract the projection of handles, cranks, sensors, or latches. Add a safety allowance to cover out‑of‑square jambs, bowed drywall, or uneven tile. If the depth margin is negative, the calculator reports spacer thickness needed to clear the obstruction.
Choosing minimum versus flush
Minimum depth allows the shade to sit partly out of the recess, reducing depth demand and improving compatibility with shallow openings. Flush depth fully recesses the assembly for a tidy face line, but requires more space for cassettes and fabric rolls. Use manufacturer bracket depth when available, or switch to custom required depth for exact products.
Using results to guide installation
When you pass, confirm screw placement and verify the head jamb is solid and level. When you fail, consider spacer blocks, moving the mount outward, or switching to an outside mount. Keep notes from the results panel and export a CSV or PDF for your project folder, especially when managing multiple windows. In gardening workspaces, label each window position, record plant light requirements, and choose fabrics that tolerate moisture for better task lighting. Consistent documentation reduces rework when replacing shades after seasonal maintenance.
FAQs
What does “available depth” mean?
Available depth is your usable recess depth after subtracting any obstruction projection. It represents the space the shade can occupy without hitting handles, cranks, sensors, or latches.
Why add a safety allowance?
Walls and frames are rarely perfectly square. The safety allowance accounts for bowed surfaces, uneven trim, measuring error, and installation tolerances so the shade does not bind after mounting.
When should I use custom required depth?
Use it when you have exact manufacturer depth specs for your product, cassette, or bracket system. It overrides presets and helps you match a specific model and mount goal accurately.
What if the calculator says I need a spacer?
Spacer blocks move the mount outward so the shade clears the obstruction. If spacer thickness becomes large, consider an outside mount or a slimmer product to keep the installation stable.
How do I choose minimum versus flush mounting?
Minimum depth works with shallow recesses and leaves part of the headrail visible. Flush mounting hides the assembly for a cleaner look but typically needs more depth for cassettes and rolls.
Do the order width and height replace manufacturer rules?
No. They provide a practical starting point using your clearance inputs. Always verify your supplier’s measuring instructions and hardware requirements before placing an order.