Throw Distance Calculator & Guide
Calculate exactly how far your projector needs to be from the screen for any image size. Master throw ratios to plan your perfect setup.
Throw Distance Calculator
Screen Width: 87"
Required Distance: 8.7 - 10.9 ft
Understanding Throw Ratio
Throw ratio is the relationship between projection distance and screen width. It's calculated as:
Throw Ratio Formula
Throw Ratio = Distance to Screen ÷ Screen Width
For example, if a projector is 10 feet from a screen that is 8 feet wide, the throw ratio is 10 ÷ 8 = 1.25:1
Throw Ratio Categories
- Ultra Short Throw (0.1 - 0.4:1): Projects from inches away. Sits directly below screen. Examples: Hisense PX1-PRO, Samsung LSP9T
- Short Throw (0.4 - 1.0:1): Projects 100" from 3-7 feet. Table placement. Examples: BenQ TH671ST, Optoma GT1090HDR
- Standard Throw (1.0 - 2.0:1): Most common. 100" from 8-15 feet. Examples: Epson 5050UB, BenQ HT3560
- Long Throw (2.0:1+): For large venues. 100" from 15+ feet. Examples: Commercial/venue projectors
Screen Width by Diagonal Size
| Diagonal (16:9) | Width | Height | Distance @ 1.2:1 | Distance @ 1.5:1 | Distance @ 2.0:1 |
|---|---|---|---|---|---|
| 80" | 70" | 39" | 7.0 ft | 8.7 ft | 11.6 ft |
| 100" | 87" | 49" | 8.7 ft | 10.9 ft | 14.5 ft |
| 120" | 105" | 59" | 10.5 ft | 13.1 ft | 17.5 ft |
| 150" | 131" | 74" | 13.1 ft | 16.4 ft | 21.8 ft |
Reverse Calculation: Distance to Screen Size
If you know how much space you have, calculate the maximum screen size:
Screen Width Formula
Screen Width = Distance ÷ Throw Ratio
Example: With 12 feet of distance and a 1.5:1 throw ratio projector, maximum screen width = 12 ÷ 1.5 = 8 feet (96") wide, which equals about 110" diagonal for 16:9.
Zoom Lenses and Throw Range
Many projectors have zoom lenses that provide a range of throw ratios (e.g., 1.2-1.5:1). This flexibility means:
- You can place the projector anywhere within the calculated range
- Zoom adjusts image size without moving the projector
- Wider zoom ranges (like 1.3-2.8:1) offer more placement flexibility
Fixed-lens projectors have a single throw ratio, requiring precise placement.
Lens Shift vs. Keystone
Lens Shift (Preferred)
Optical adjustment that moves the projected image up/down or left/right without affecting image quality. Found on mid-range and higher projectors.
- No image degradation
- Maintains full resolution
- Allows off-center placement
Keystone Correction
Digital adjustment that corrects trapezoidal distortion when projecting at an angle. Uses processing to reshape the image.
- Reduces effective resolution
- Can soften image details
- Use only when necessary
Pro Tip: Center Your Projector
For the best image quality, mount or place your projector directly in front of the screen center, perpendicular to the screen surface. This eliminates the need for keystone correction and ensures uniform focus across the entire image.
Don't Forget Vertical Offset
Most projectors don't project straight forward - the image typically appears above the lens centerline. Check your projector's vertical offset specification to determine proper mounting height. Without lens shift, the projector lens should align with the bottom or top edge of your screen.