Master throw ratio calculations, learn the difference between standard, short throw, and UST projectors, and find exactly where to place your projector.
Enter your screen size and room dimensions to find exact placement requirements.
Throw distance is the measurement from a projector's lens to the screen surface. This single measurement determines how large your projected image will be - the farther the projector from the screen, the larger the image.
Understanding throw distance is essential for projector setup because it answers the most basic question: "Where do I put my projector?"
Every projector has a specific throw ratio (or range of ratios with zoom) that determines the relationship between distance and image size. Our throw distance calculator helps you find the exact placement for any projector.
Throw ratio is the relationship between throw distance and screen width. It's expressed as a single number (like 1.5) or range (like 1.2-1.5 for projectors with zoom).
Throw Ratio = Distance to Screen / Screen Width
A throw ratio of 1.5 means for every 1 foot of screen width, the projector needs 1.5 feet of distance.
Ultra-short throw projectors. Sit inches from the screen. Best for limited spaces, golf simulators, and avoiding shadows.
Short throw projectors. Position 3-8 feet from screen for 100-inch image. Good balance of flexibility and space savings.
Standard throw projectors. Need 10-15+ feet for large images. Most affordable option if you have the room depth.
Standard throw projectors have throw ratios typically between 1.4 and 2.0. They're the most common and affordable option, requiring significant distance between projector and screen. See our best projector for room size guide to find which type fits your space.
Short throw projectors have throw ratios between 0.4 and 1.0. They create large images from closer distances, typically sitting 3-8 feet from the screen for a 100-inch image.
UST projectors have throw ratios under 0.4, often around 0.2-0.3. They sit just inches to 2 feet from the screen, projecting upward at a sharp angle.
Once you know your throw type, see our best home theater projectors, best UST projectors, and best projector mounts guides for top picks at every throw ratio.
Screen sizes are measured diagonally, but throw distance is calculated using width. Use our screen size calculator to determine the ideal screen size for your seating distance. For 16:9 aspect ratio screens:
Screen Width = Diagonal Size x 0.87
| Screen Size | Width |
|---|---|
| 100" | 87" (7.25 ft) |
| 120" | 104.5" (8.7 ft) |
| 135" | 117.7" (9.8 ft) |
| 150" | 130.7" (10.9 ft) |
Once you know your screen width and projector's throw ratio:
Throw Distance = Screen Width x Throw Ratio
For a 120" screen with a projector having a 1.5 throw ratio:
Most projectors have optical zoom that provides flexibility. A projector with a 1.2-1.5 throw ratio range can be positioned anywhere within that range for the same screen size.
Our throw distance calculator handles all these calculations automatically, including zoom ranges for specific projector models.
Quick reference for common screen sizes and projector types. All distances in feet.
Most popular option for home theaters. The projector hangs upside-down from the ceiling, typically behind and above the seating area.
Projector sits on furniture behind the seating area. Works well for rentals or when ceiling mounting isn't possible.
Ultra-short throw projectors sit on furniture directly below the screen, projecting upward.
Optical zoom lets you adjust image size without moving the projector, which also affects how much brightness reaches the screen. A projector with "1.3x zoom" can make the image 30% larger or smaller from the same position. This translates to flexibility in throw distance - you can position the projector anywhere within a range rather than at one exact spot.
A projector with 1.2-1.5 throw ratio (1.25x zoom) for a 120" screen:
Lens shift physically moves the lens to offset the image vertically or horizontally without moving the projector body or causing distortion.
Both adjust image position, but they work differently:
Throw distance is the distance between a projector's lens and the screen. It determines how large an image the projector creates at any given distance. Knowing your throw distance helps you choose the right projector and placement for your room.
Throw ratio is the relationship between throw distance and screen width. Calculate it by dividing the distance from projector to screen by the screen width. A throw ratio of 1.5 means for every 1 foot of screen width, the projector needs 1.5 feet of distance. Standard projectors have ratios of 1.4-2.0, short throw is 0.4-1.0, and UST is under 0.4.
For a 120-inch (16:9) screen with 104.6 inches of width: A standard projector (1.5 ratio) needs about 13 feet. A short throw projector (0.5 ratio) needs about 4.4 feet. An ultra-short throw projector (0.2 ratio) needs only about 1.7 feet from the screen. Use our throw distance calculator to find exact measurements for your projector model.
Short throw projectors have throw ratios between 0.4-1.0, placing them 3-8 feet from the screen for a 100-inch image. Ultra short throw (UST) projectors have ratios under 0.4, sitting just inches to 2 feet from the screen. UST projectors are ideal for limited spaces, golf simulators, and avoiding shadows.
You need a short throw projector if: your room depth is less than the throw distance required for a standard projector, you want to avoid walking through the beam, or you're setting up a golf simulator where the ball flight would block a standard projector. Use our throw distance calculator to check if standard throw works for your room.
Yes, most projectors have optical zoom that provides flexibility in placement. A projector with 1.3x zoom and a base throw ratio of 1.5 can operate between ratios of 1.5-1.95. This allows 30% flexibility in distance for the same screen size, making installation easier.
Lens shift moves the projected image up, down, or sideways without moving the projector or causing distortion. It's useful when you can't mount the projector perfectly centered or at screen height. Vertical lens shift is most common and helpful for ceiling mounts. Keystone correction is a digital alternative but reduces image quality.
Ceiling mount is most common, placing the projector upside-down above and behind the seating area. For UST projectors, floor or shelf mounting directly below the screen works best. Calculate your throw distance first, then position the projector at that distance from the screen, using lens shift to fine-tune vertical alignment.
Continue reading with these related guides
Complete guide to building a dedicated home theater from projector selection to calibration.
UST projector requirements and placement for indoor golf setups.
Find the right projector for any space, from small apartments to dedicated home theaters.