Throw Distance
13.1 ft
Screen Width
104.6 in
ft-Lamberts
22.3
Throw Type
Standard Throw
Adequate for some ambient light conditions. Target is 28 fL.
Inputs
Result
Screen width = 120 × 0.8716 = 104.6″. Throw distance = 1.5 × 104.6 / 12 = 13.1 ft. Screen area = 104.6 × 58.8 / 144 = 42.7 sq ft. fL = 3000 × 1.0 / (42.7 × π) = 22.4 fL.
Inputs
Result
Screen width = 100 × 0.8716 = 87.2″. Throw distance = 0.6 × 87.2 / 12 = 4.4 ft. Screen area = 87.2 × 49.0 / 144 = 29.7 sq ft. fL = 2500 / (29.7 × π) = 26.8 fL.
Inputs
Result
For 4:3, width factor = 0.8. Screen width = 150 × 0.8 = 120″. Throw distance = 2.0 × 120 / 12 = 20.0 ft. Screen area = 120 × 90 / 144 = 75.0 sq ft. fL = 5000 / (75.0 × π) = 21.2 fL.
Multiply the projector’s throw ratio by the screen width. For a 120-inch 16:9 screen, the width is about 104.6 inches. With a 1.5 throw ratio, the throw distance is 104.6 × 1.5 = 156.9 inches (13.1 feet). The throw ratio is listed in your projector’s spec sheet.
| Screen Size | Width (16:9) | Distance (1.5 ratio) | Distance (2.0 ratio) |
|---|---|---|---|
| 100" | 87.2″ | 10.9 ft | 14.5 ft |
| 120" | 104.6″ | 13.1 ft | 17.4 ft |
| 150" | 130.7″ | 16.3 ft | 21.8 ft |
| 200" | 174.3″ | 21.8 ft | 29.1 ft |
Standard home theater projectors have a throw ratio of 1.0 to 2.0. A ratio of 1.4–1.6 is most common and works well in rooms 10–18 feet deep. Short-throw projectors (0.4–0.8) suit small rooms, and ultra-short-throw models (0.2–0.4) mount inches from the wall.
| Throw Type | Ratio Range | 120″ Screen Distance | Best For |
|---|---|---|---|
| Ultra Short | 0.2–0.4 | 1.7–3.5 ft | Wall-mounted, living rooms |
| Short | 0.4–0.8 | 3.5–7.0 ft | Small rooms, apartments |
| Standard | 1.0–2.0 | 8.7–17.4 ft | Dedicated home theaters |
| Long | 2.0–3.0 | 17.4–26.2 ft | Auditoriums, churches |
It depends on screen size and ambient light. In a dark room, 1,500–2,000 lumens is sufficient for screens up to 150 inches. A room with some ambient light needs 2,500–3,500 lumens. Bright rooms with no curtains require 3,500–5,000+ lumens for a watchable image.
| Room Type | Lumens Needed | Target fL | Max Screen Size (2000 lm) |
|---|---|---|---|
| Dark | 1,500–2,000 | 12–22 fL | ~150″ |
| Dim | 2,500–3,500 | 22–35 fL | ~100″ |
| Moderate | 3,500–5,000 | 35–50 fL | ~80″ |
| Bright | 5,000–7,000+ | 50+ fL | ~60″ |
Foot-Lamberts (fL) measure the actual brightness reaching your eyes from the screen. Unlike raw lumens, fL accounts for screen size and gain. A 3,000-lumen projector on a 100-inch screen produces more fL than the same projector on a 150-inch screen. The SMPTE standard for cinemas is 14–22 fL.
Screen gain does not affect throw distance, but it significantly affects perceived brightness. A 1.3-gain screen makes a 3,000-lumen projector appear as bright as a 3,900-lumen projector on a 1.0-gain screen. However, higher-gain screens narrow the viewing angle, so off-axis seats see a dimmer image.
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Last Updated: Mar 9, 2026
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