Awning Size Planner
Tell the planner what you want to cover and it recommends a width, projection, pitch and mounting height, checking headroom and drainage and, for patios, how much shade each projection actually delivers at your latitude.
The sizing rules behind the planner
| Application | Width | Projection | Height and pitch |
|---|---|---|---|
| Patio or deck | Area width plus about 1 ft each side | Chosen so shade covers your depth at your main time of use (August 1 design day) | Front bar 7 ft or higher; pitch at least about 14° for drainage where headroom allows |
| Window | Trim width plus about 3 in each side | South: 1/2 to 2/3 of window height; east and west: 2/3 to the full height, with sides | Top 6 to 10 in above the trim |
| Door | Trim width plus about 9 in each side | At least 3 ft, ideally covering the landing | Top 6 to 12 in above the trim; edge at least 7 ft above the walking surface |
For a patio, the planner tests every common projection from 8 to 13 ft. For each, it finds the steepest pitch that still keeps the front bar at 7 ft, caps it at the 35° most retractables allow, and computes the shade depth with real sun angles. It recommends the smallest projection that shades your target depth, because extra projection costs money and adds load on the wall.
Measuring is where most sizing errors happen. Before ordering, follow our step-by-step guide to measuring for an awning, and check projection and pitch, window awning sizing and door awning sizing for the details.
Frequently asked questions
What size awning do I need for a 12 by 12 patio?
For a 12 ft wide area, plan on a 14 ft wide awning so the shade still covers the edges as the sun moves. For 12 ft of depth, a south-facing wall in most of the US needs roughly a 12 to 13 ft projection for midday shade over the full depth, often more in late afternoon on west walls. Run the planner with your mounting height and orientation for a specific answer.
Should an awning be wider than the area it covers?
Yes. The sun is rarely square to the wall, so the shadow shifts sideways during the day. An extra foot or so on each side keeps chairs at the ends of a table in shade for longer. For windows, a few inches beyond the trim each side blocks light that would otherwise slip past the edges.
How high should an awning be mounted?
High enough that the front bar stays at least about 7 ft above the ground at your chosen pitch. For a 10 ft projection at 14 degrees, the front drops about 2.4 ft, so the brackets need to sit around 9.5 ft or higher. If the wall is not tall enough, soffit or roof brackets can raise the mounting point.