Always measure the rough opening — the structural opening in the wall, not the existing window frame or trim. If measuring from outside, measure the full masonry or frame opening. If measuring from inside, measure between the interior stops and add 1 inch to each dimension.
Measure the Width
Horizontal measurement — left corner to right corner
Stand outside facing the window. Place your tape measure at the left outer corner of the window frame or masonry opening.
Extend the tape to the right outer corner. Record this measurement in inches — this is your exact width.
Use this number directly in the configurator.
From inside, place your tape measure at the left interior stop (the inner edge of the window frame where the sash rests).
Extend to the right interior stop. Record this measurement, then add 1 inch to account for the frame depth hidden in the wall.
Enter the adjusted measurement (original + 1″) in the configurator.
Measure the Height
Vertical measurement — top edge to bottom edge
From outside, place your tape measure at the top outer edge of the window frame or masonry opening.
Extend the tape straight down to the bottom outer edge. Record this measurement in inches — this is your exact height.
Use this number directly in the configurator.
From inside, place your tape measure at the top interior stop (the inner edge of the top frame where the sash rests).
Extend straight down to the bottom interior stop (top of the sill). Record this measurement, then add 1 inch.
Enter the adjusted measurement (original + 1″) in the configurator.
Pro Tips for Accurate Measurements
Measure Twice
Always measure each dimension at least twice to confirm consistency. A small error can mean a window that doesn't fit.
Use a Metal Tape
A rigid metal tape measure gives more accurate results than a fabric tape, especially for larger openings.
Note the Smallest Value
If you get slightly different readings at different points (top vs. bottom for width), always use the smallest measurement.
Quick Reference
| Measurement | From Outside | From Inside |
|---|---|---|
| Width | Corner to corner — use as-is | Inner stop to inner stop + 1″ |
| Height | Top edge to bottom edge — use as-is | Top stop to sill top + 1″ |