How window size codes work
Sizes are written width × height. Manufacturer codes often use feet and inches: a 2030 window is 2′0″ wide by 3′0″ high; a 3050 is 3′0″ by 5′0″.
Common size ranges by type
| Type | Common widths | Common heights |
|---|---|---|
| Double-hung / single-hung | 24″-48″ | 36″-72″ |
| Sliding | 36″-84″ | 24″-60″ |
| Casement | 14″-36″ per sash | 24″-72″ |
| Picture | 24″-96″ | 12″-96″ |
| Awning | 24″-48″ | 20″-36″ |
| Basement hopper | 24″-36″ | 12″-24″ |
Ranges are typical; check your manufacturer’s size chart.
How to measure for an insert replacement
- Measure the width inside the existing frame, jamb to jamb, at the top, middle and bottom. Use the smallest.
- Measure the height from the head jamb to the sill at left, center and right. Use the smallest.
- Check the frame is square: measure both diagonals.
Your installer will re-measure before ordering: custom-made windows aren’t returnable.
Bedroom egress sizes
Bedroom windows usually must meet egress rules. See egress windows.
