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Measurement guide

How to Measure for Shades

Shades only — this guide applies to roller shades and cellular shades. Drapery, shutters, and specialty treatments use different measuring rules.

Get accurate measurements the first time. This guide covers inside mount, outside mount, common obstructions, and a fraction-to-decimal conversion table.

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Also measuring for: Plantation shutters › Custom drapery ›
Tab 1 of 4
Inside Mount

An inside mount shade fits entirely within the window frame — the shade hangs inside the casing and gives a clean, built-in appearance. This is the most popular style when the frame is deep enough to accommodate it.

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Critical: minimum 2‑3/4” depth required for inside mount

Your window frame must have at least 2‑3/4 inches of clear, unobstructed depth — measured from the face of the opening straight back — for an inside mount shade to fit. If your frame is shallower, or if handles, cranks, or sensors occupy that space, you must switch to outside mount. We verify this on every in-home measurement.

W1 W2 W3 H1 H2 Measure inside the window frame opening
What the labels mean:
  • W1 Width at top of opening — inside frame edge to inside frame edge
  • W2 Width at middle of opening
  • W3 Width at bottom of opening
  • H1 Height on the left side — top of frame to sill
  • H2 Height on the right side — top of frame to sill
Order using: the smallest of W1/W2/W3 and the tallest of H1/H2. We handle the deductions.
Step-by-step
How to measure for inside mount
  1. Measure width in 3 places — top (W1), middle (W2), and bottom (W3) of the window opening, from inside frame edge to inside frame edge. Record all three numbers.
  2. Use the smallest width — if W1, W2, and W3 differ, order using the narrowest measurement. This ensures the shade clears the tightest point in the frame as it travels up and down.
  3. Measure height in 2 places — left side (H1) and right side (H2) of the opening, from the top of the frame straight down to the sill.
  4. Use the tallest height — order using the larger of H1 and H2 so the shade fully covers the opening at its tallest point.
  5. Order with these exact measurements — submit the smallest width and tallest height as you measured them. Do not pre-deduct anything. We make all necessary deductions before fabrication.
Real job-site example
Annotated window measurement photo from a real Philly Blinds job site — inside widths, outside span, heights, and trim depths all recorded in red
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How we record measurements in the field. Every number you see written in red is a separate measurement taken on this window configuration — inside width at the glass (73″), full outside span (131¾″), inside heights at left and right (66⅞″ / 66¾″), lower panel dimensions, trim depth, and wall-to-frame offsets for outside mount calculations. This is exactly what we capture on every in-home visit so your shades are cut to fit the first time.

Why we make deductions on your behalf

An inside mount shade must clear the frame on both sides as it raises and lowers. We subtract approximately 1/4” to 1/2” from the width you provide before the shade is cut — the exact amount varies by product. That is why you measure the true opening and let us do the math. Never pre-deduct before ordering.

Pro tips — inside mount

  • Use a steel tape measure, not a cloth or flexible tape that can sag or stretch
  • Measure to the nearest 1/8 inch — fractions matter for a proper fit
  • Measure with the window closed so the sash does not shift the frame dimensions
  • Measure every window individually — even “identical” windows in the same room vary slightly
  • Check your depth at all four corners — some frames taper near the corners
  • When in doubt, book our free in-home measurement — we bring the tools and guarantee accuracy

Still not sure? We’ll walk you through it live.

Call or text any time — 24/7. Or book a free in-home measurement and we handle everything.

(609) 742-1720 24/7 · call or text Book free measurement
Tab 2 of 4
Outside Mount

An outside mount shade mounts on the wall, trim, or ceiling above the window opening. The shade covers the entire frame and extends beyond it on both sides. This style works for any window regardless of depth and is the best choice for maximum light blockage.

For outside mount roller or cellular shades, the width can be based on the outside width of the window frame, casing, or sill. For better light control, we recommend extending the shade 1–2 inches past each side of the frame when possible. For the strongest installation, the final width should also consider where the brackets can hit solid framing or studs.

bracket / mount point mount 3"–4" above opening SHADE WIDTH 1–2" min 1–2" min HGT Outside mount size = finished shade size. Do not deduct.
What you control:
  • WIDTH Window opening + at least 2” per side = finished shade width
  • HEIGHT From bracket/mount point to sill, plus 2”–3” extra
Important: For outside mount, we do not deduct from your measurement. The number you submit is the finished shade size.
Step-by-step
How to measure for outside mount
  1. Decide how wide you want the shade — start from the outside width of the frame, casing, or sill, then add 1–2 inches per side when possible for better light control. Consider stud or framing locations when placing brackets.
  2. Decide where to mount the bracket — typically 3”–4” above the window casing or at the ceiling. Mark this point. Mounting higher creates the illusion of taller windows and eliminates the light gap at the top.
  3. Measure from the mounting point down to the sill (or to the floor if you want the shade to stack there). This is your starting height.
  4. Allow extra height for the product hardware — roller shades may need additional height for brackets, fascia, cassette, or roll size. Cellular shades may need additional height for the headrail and fabric stack when the shade is raised. Adjust the final height based on the selected product.

Outside mount height — product hardware allowance

Outside mount height should include enough room above the frame for the product hardware. Roller shades may need extra height for brackets, fascia, cassette, or roll size. Cellular shades may need extra height for the headrail and fabric stack when the shade is raised. The final height should be adjusted based on the selected product.

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Minimizing light gaps on the sides

Light leaks in around the sides when the shade isn’t wide enough. For blackout needs — bedrooms, home theaters, nurseries — we recommend 3”–4” overlap per side. Ask us about side-channel cassette shades for near-total blackout results.

Pro tips — outside mount

  • Outside mount width may follow the frame, casing, or sill width
  • Add 1–2 inches per side when possible for better light control
  • Wider may also help place brackets into solid framing or studs
  • For roller shades, allow extra height for brackets, fascia, cassette, or roll size
  • For cellular shades, allow extra height for headrail and stack when raised
  • Outside mount measurements are finished shade sizes. Do not deduct

Still not sure? We’ll walk you through it live.

Call or text any time — 24/7. Or book a free in-home measurement and we handle everything.

(609) 742-1720 24/7 · call or text Book free measurement
Tab 3 of 4
Obstructions & Tips

Before you measure, walk through each window and check for anything that may affect your mounting option. Use the groups below to identify issues before ordering.

FACE 2-3/4" MINIMUM Clear depth inside the frame opening

Minimum depth for inside mount: 2-3/4”

Measure from the face of the frame opening straight back to the first obstruction (glass, sash, handle, or sensor). If clear depth is less than 2–3/4”, choose outside mount.

Measure after all trim and casing are installed — not over rough openings.

⛔ STOP — These prevent inside mount
Window cranks or handles in the frame

Casement or awning cranks that protrude into the frame opening reduce usable depth and physically block the shade. Use outside mount or a shallow-profile product instead.

Inward-tilting or tilt-in windows

Windows that tilt inward for cleaning will be blocked by an inside mount shade. You would not be able to open or clean the window without removing the shade each time.

Window alarm sensors in the frame corner

Sensors mounted in the inside corner of the frame reduce the usable opening and can prevent the shade from traveling properly. Relocate the sensor or switch to outside mount.

⚠ CAUTION — Check before measuring
Window screens

Remove the screen before measuring. Screens add a small amount to the effective opening and are typically reinstalled after shade installation, not before it.

Built-in blinds between glass panes

Some windows have integrated blinds inside the double-pane unit. These windows often have very shallow usable depth. Measure carefully — inside mount may not be possible.

Decorative grilles or muntins

Grilles applied to the glass face can interfere with the bottom bar of a shade. Inside mount is often still possible — note the grille configuration when ordering so we can verify clearance.

✓ OK — These are fine for inside mount
Outside-mounted handles

Handles on the exterior of the window do not affect inside depth at all. No clearance issue.

Standard casement windows

Side-hinged casements that swing outward are fine as long as the crank is not inside the frame opening. Measure with the window closed.

Thermal double or triple pane windows

Multi-pane glass units do not affect inside mount. The frame geometry is all that matters — pane count has no impact.

Cleaning access with inside mount

Most inside mount roller and cellular shades can be tilted or unclipped from their brackets for window cleaning. No need to permanently remove the shade.

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Always measure after trim and casing are fully installed

If you are renovating, wait until all window trim, casing, and stool are completely installed before measuring. These components reduce the usable frame opening. Measuring rough openings will give incorrect dimensions.

Still not sure? We’ll walk you through it live.

Call or text any time — 24/7. Or book a free in-home measurement and we handle everything.

(609) 742-1720 24/7 · call or text Book free measurement
Tab 4 of 4
Fraction Cheat Sheet

All shade measurements should be to the nearest 1/8 inch. Our order forms accept both fraction format (36-1/8) and decimal format (36.125) — both are identical and either is accepted.

Fraction Decimal equivalent Example on a 36” window
1/8” 0.125” 36‑1/8”  or  36.125”
1/4” 0.250” 36‑1/4”  or  36.250”
3/8” 0.375” 36‑3/8”  or  36.375”
1/2” 0.500” 36‑1/2”  or  36.500”
5/8” 0.625” 36‑5/8”  or  36.625”
3/4” 0.750” 36‑3/4”  or  36.750”
7/8” 0.875” 36‑7/8”  or  36.875”
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Use a steel tape measure

A metal-blade tape measure gives you the most accurate reading. Cloth tape measures stretch over time and can read 1/4” or more off. Flexible plastic tapes have the same problem. A standard 16-ft or 25-ft metal tape is ideal for window measurements.

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Measure twice, order once

Always measure each window a second time before writing anything down. If the two readings differ, take a third and use the smaller of the three for inside mount width. Custom shades cannot be returned once cut — accuracy upfront prevents costly remakes.

How to enter fractions on our order form

Type fractions using a hyphen and slash: 36-1/8 means 36 and one-eighth inches. You can also type the decimal: 36.125. Both produce identical results. Never round to the nearest whole inch — the 1/8” increments are critical for a proper fit.

Measuring best practices

  • Read the tape at eye level directly above the point — reading at an angle causes parallax errors of 1/16”–1/8”
  • Hook the tape over the inside edge of the frame rather than butting the tip against it for more consistent readings
  • Write each measurement down immediately — do not rely on memory, especially with multiple windows
  • Label measurements per window on a simple sketch: “Living Room Left: W 36-1/4, H 54-1/2”
  • Photograph each window after measuring — the image timestamp helps if questions come up later

Still not sure? We’ll walk you through it live.

Call or text any time — 24/7. Or book a free in-home measurement and we handle everything.

(609) 742-1720 24/7 · call or text Book free measurement
Separate Guide
Drapery Measuring Guide

Drapery uses a different measuring process than roller or cellular shades. For drapery, we need architectural measurements of the window, surrounding walls, ceiling height, obstructions, and door handle direction when applicable.

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Photos required

Please take clear photos of the full window or door, the surrounding wall area, the frame, nearby furniture, TVs, trim, ceiling, and floor. These photos help determine rod placement, stack space, and finished drapery height.

CEILING C D E Arrows start at the outside edge of the frame
Three key clearances to measure:
  • C
    Left side clearance — from the outside left edge of the frame to the nearest wall, TV, furniture, or cabinet on that side
  • D
    Right side clearance — from the outside right edge of the frame to the nearest wall, TV, furniture, or cabinet on that side
  • E
    Above-frame clearance — from the outside top edge of the frame up to the ceiling or crown molding
Also measure: frame-to-frame outside width, frame-to-floor height, and ceiling-to-floor height — all covered in the step list below.
Required drapery measurements
What to measure
  1. Frame-to-frame outside width — measure the full outside width of the window or door frame.
  2. Frame-to-floor height — measure from the top of the frame down to the floor.
  3. Left side clearance — measure from the left side of the frame to the nearest wall, furniture, TV, cabinet, or obstruction.
  4. Right side clearance — measure from the right side of the frame to the nearest wall, furniture, TV, cabinet, or obstruction.
  5. Above-frame clearance — measure from the top of the frame to the ceiling or crown molding.
  6. Ceiling-to-floor height — measure the full ceiling height down to the floor.
  7. Slider door handle side — if measuring a sliding door, note whether the handle is on the left or right side.

Rod height recommendation: As a starting point, rod height is often placed about halfway between the top of the frame and the ceiling. Final height may change depending on hardware style, ceiling height, stack space, and finished drapery length.

Stack estimate logic
Approximate drapery stack calculation

Stack calculation

Cuts = (Rod Width × 2.5 fullness) ÷ 54. Round up to the next whole cut.
Approximate pleats = Cuts × 5.
Approximate carrier stack = Pleats × 0.625 inches.
For split draw, divide stack by 2 and round up.
For one-way draw, do not divide the stack.

Overlap and fullness allowance

Add approximately 4 inches of overlap per panel where needed. Add 1–2 inches of extra “fluff” allowance for visual fullness and ease of operation.

Drapery notes

  • Drapery rod width is not always the same as the window width
  • Stack space must be checked on both sides of the window
  • Nearby furniture, TVs, walls, cabinets, and doors can affect stack direction
  • Sliding doors must include handle side so the draw direction can be planned correctly
  • Drapery measurements should be reviewed before final quoting

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