Projector throw ratio calculator
Enter your throw distance and screen size to get the exact throw ratio your projector needs — with a short/standard/long-throw verdict and a setup reference table.
Throw ratio = throw distance ÷ image width, in the same unit. A projector 10 ft from a 100-inch 16:9 screen (87.2″ wide) needs a throw ratio of about 1.38:1 — a standard-throw lens. Enter your distance and screen size below to get the ratio your room demands.
Throw ratio by distance and screen size
| Distance | 80″ | 100″ | 120″ | 150″ |
|---|---|---|---|---|
| 6 ft | 1.03 | 0.83 | 0.69 | 0.55 |
| 8 ft | 1.38 | 1.10 | 0.92 | 0.73 |
| 10 ft | 1.72 | 1.38 | 1.15 | 0.92 |
| 12 ft | 2.07 | 1.65 | 1.38 | 1.10 |
| 15 ft | 2.58 | 2.07 | 1.72 | 1.38 |
| 20 ft | 3.44 | 2.75 | 2.29 | 1.84 |
How throw ratio is calculated
Throw ratio is the lens-to-screen distance divided by the image width, measured in the same unit. A 16:9 screen is 0.872 × its diagonal wide — a 100″ screen is 87.2″ (2.21 m) across — so a projector sitting 10 ft (120″) back needs 120 ÷ 87.2 ≈ 1.38. Zoom lenses cover a range (a typical 1.3× zoom spans ~1.32–1.71), so any distance inside that window works; fixed-lens and ultra-short-throw projectors must match the number closely. Under ~0.4 you are in UST territory and should plan for a CLR screen.
Find the throw ratio you need
1.38:1
Required throw ratio
Standard throw (1.0 – 2.0)
Image width: 87.2″. Pick a projector whose lens (or zoom range) covers this ratio.
Frequently asked questions
Updated