DecorMeasure
🪟 Casing Depth & Mounting Architecture • Factory Deductions Explained

Window Blinds & Shades Mount Planner

Determine whether your window depth supports a clean, recessed inside mount or requires an outside mount over the trim. Checks bracket depth requirements, flush headrail clearances, and ordering sizes.

Window Frame Dimensions

Measure top, middle, bottom
Measure left, middle, right
Clear unobstructed depth from front edge of window trim back to the glass pane or window crank.
Total extra width (2″ per side)
Above trim + below sill
Mount Feasibility Diagnostic Inside Mount Feasible

Recommended: Inside Mount (Flush Fit)

Your window casing depth (2.75″) satisfies both the minimum mounting depth (1.5″) and the flush mount depth (2.75″). The headrail will sit entirely inside the frame without protruding.

Architectural Casing Depth Cross-Section
If Ordering Inside Mount:
Order Width: 35 1/2″
Order Height: 59″
*Factory takes 3/8″ deduction
If Ordering Outside Mount:
Order Width: 39 1/2″
Order Height: 63″
*Includes 4″ overlap for privacy
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AI Visualization Prompt

Measurement-aware prompt for ChatGPT, Gemini, or Midjourney

Inside Mount vs. Outside Mount Guidelines

The golden rule of ordering custom window blinds is: never take your own deductions for inside mounts. Always provide the exact, tightest measurement of your window opening. The fabricator will automatically deduct 1/4″ to 3/8″ to ensure the blind raises and lowers freely without scraping your casing.

When Must You Choose Outside Mount?

  • When your window frame depth is less than the manufacturer's minimum mounting depth (usually under 1.25″–1.5″).
  • When window cranks, alarm sensors, or sliding track handles obstruct the inside recess.
  • When you want complete blackout coverage in a bedroom (outside mount eliminates side light gaps).