Projector Throw Distance Calculator | Distance for a 100-Inch Screen from the Throw Ratio, Screen Size from Your Distance, Image Height for Ceiling and Table Mounting, the Right Size for Your Room, Viewing Distance, Brightness from Lumens, and a Screen Size Chart
The Projector Throw Distance Calculator answers two questions: how far from the wall does the projector need to be for a 100-inch image, and how big an image can you get in your room? It works from the throw ratio (throw distance ÷ image width). Choose a 16:9, 16:10, 4:3 or 21:9 aspect ratio and a typical throw ratio for a home projector, a long-zoom home theater projector, a mobile projector, a short throw or an ultra short throw model, or type in the values from the spec sheet. For zoom lenses it shows the full range of positions between the wide and tele ends. For table and ceiling mounting it uses the lens height and offset to give the height of the bottom and top of the image from the floor, with a side view so you can check the image stays between floor and ceiling. Enter your room by tatami mats (as used in Japanese homes) or by its dimensions to get the largest size that fits the throw distance, wall width and ceiling height, and the size that is comfortable from where you sit. Viewing distance follows SMPTE (30° field of view), THX (36° and 40°), Full HD (3 × image height) and 4K (1.5 × image height), in both directions. From lumens (ANSI or LED lumens) and screen gain it calculates image brightness in cd/m², whether it is enough for a dark room or a lit living room, and the largest comfortable size. A chart lists width, height and throw distance from 40 to 150 inches.
Projector and screen
The throw ratio is throw distance ÷ image width. Entering the value from your model's spec sheet is the most accurate.
Aspect ratio
Throw ratio
Throw distance and screen size
Get the throw distance from the size you want, or the size you get from the distance you have.
Throw distance (lens to screen)
2.66 m (8 ft 9 in) – 3.32 m (10 ft 11 in)
Image width and height (100 in)
221 cm wide × 125 cm high
Mounting height
Offset is the distance from the lens center to the edge of the image as a percentage of the image height. At 100%, the bottom of the image sits at lens height on a table.
Bottom of the image (from the floor)
185 cm
Top of the image (from the floor)
309 cm
The top of the image is above the ceiling. Use a smaller size or lower the lens.
ABOUT
About Projector Throw Distance Calculator | Distance for a 100-Inch Screen from the Throw Ratio, Screen Size from Your Distance, Image Height for Ceiling and Table Mounting, the Right Size for Your Room, Viewing Distance, Brightness from Lumens, and a Screen Size Chart
The Projector Throw Distance Calculator uses the throw ratio to work out the throw distance for the screen size you want, and the screen size you get from the distance you have. It also covers the image height for ceiling or table mounting, the right size for a room measured in tatami mats or centimeters, viewing distance guidelines, screen brightness from lumens and a 40–150 inch chart.
How to use Projector Throw Distance Calculator | Distance for a 100-Inch Screen from the Throw Ratio, Screen Size from Your Distance, Image Height for Ceiling and Table Mounting, the Right Size for Your Room, Viewing Distance, Brightness from Lumens, and a Screen Size Chart
- 1Choose the aspect ratio (16:9 for most video) and your projector's throw ratio. If the spec sheet says “throw ratio 1.2–1.5:1”, enter those values
- 2Under “Screen size to distance”, enter the size to get the distance from the lens to the screen. If the position is fixed, switch to “Distance to screen size” and enter the distance
- 3Under “Mounting height”, choose table or ceiling, enter the lens height and offset, and check in the diagram that the image stays between floor and ceiling
- 4To start from the room, enter its size in tatami mats or centimeters under “Screen size for your room” and see the recommended size and which dimension limits it
- 5Use “Viewing distance” and “Brightness (lumens)” to check the size suits your seat and how bright the room is
Great for
- Find how far from the wall the projector must be for a 100-inch image
- Find how large an image you get when the table position is fixed
- Decide what screen size to buy for a small bedroom or living room
- Check that the top of the image stays below the ceiling with a ceiling mount
- Find a comfortable screen size for where the sofa is
- Check whether your projector's lumens are enough with the lights on
- Look up the width and height of a 100-inch or 120-inch screen in centimeters
Good to know
- The throw ratio is throw distance ÷ image width. With a 1.2 throw ratio, a 16:9 100-inch image 221 cm wide needs 221 × 1.2 ≈ 2.66 m. With a zoom lens you can get the same size anywhere between the wide end (smaller ratio) and the tele end (larger ratio).
- Throw distance is measured from the front of the lens to the screen. Manufacturers' charts sometimes measure from the front of the body, or for ultra short throw models from the back of the body to the wall, which can differ by several centimeters or more.
- Width and height come from the diagonal (inches × 2.54 cm) and the aspect ratio. A 16:9 100-inch image is about 221 × 125 cm; a 4:3 100-inch image is about 203 × 152 cm.
- Offset is the distance from the lens center to the bottom edge of the image (the top edge when ceiling mounted) as a percentage of the image height. At 100%, the bottom of the image sits exactly at lens height on a table. Projectors with lens shift can move the image up and down within their range.
- Room sizes by tatami are approximate inside dimensions built from the short side of a mat (Edoma 88 cm, Danchima 85 cm, Chukyoma 91 cm, Kyoma 95.5 cm). A 6-mat Edoma room is about 352 × 264 cm. Real rooms are a few centimeters smaller because of pillars and wall thickness, so enter measurements when you can.
- Viewing distance guidelines are the distances giving a 30° (SMPTE), 36° (the immersive angle THX recommends) and 40° (THX maximum) horizontal field of view, plus 3 × image height (Full HD) and 1.5 × image height (4K).
- Image brightness in cd/m² is lumens × gain ÷ (π × image area in m²). ANSI lumens and ISO lumens (ISO 21118) are nearly the same. “LED lumens” have no fixed measurement method, so they are converted as roughly 1/2.4 of ANSI lumens as a guide. Eco and color-accurate modes are dimmer than the rated brightness.
- Your values are saved only in this browser and are never sent to a server.
Questions this tool answers
Use Projector Throw Distance Calculator | Distance for a 100-Inch Screen from the Throw Ratio, Screen Size from Your Distance, Image Height for Ceiling and Table Mounting, the Right Size for Your Room, Viewing Distance, Brightness from Lumens, and a Screen Size Chart for searches like these:
- Calculate projector throw distance from the throw ratio
- Find the distance needed for a 100-inch or 120-inch image
- Find the screen size I can get from the space I have
- Find the right projector screen size for my room
- Find where the image sits with a ceiling or table mount
- Find the viewing distance for my screen size
- Check whether my projector's lumens are enough for the room
FAQ
- How far should the projector be from the wall for a 100-inch screen?
- Multiply the throw ratio by the image width. A 16:9 100-inch image is about 221 cm wide, so a 1.2 throw ratio needs about 2.66 m, 1.5 needs about 3.32 m, and a 0.5 short throw needs about 1.1 m. With a 1.2–1.5 zoom you can place it anywhere from 2.66 to 3.32 m and still get 100 inches.
- What is the throw ratio?
- It is the throw distance divided by the image width, written like “1.2:1”. The smaller the number, the bigger the image from close up. Around 0.4–0.8 is usually called short throw and below 0.4 ultra short throw. If the spec sheet only says “100 inches at 3 m”, you can work it out as 3 m ÷ 2.21 m ≈ 1.36.
- What screen size suits a 6-tatami room?
- In a 6-mat Edoma room (about 352 × 264 cm) projecting onto the short wall, the largest size that fits the wall width with 10 cm on each side is about 110 inches. Sitting 60 cm from the back wall, the 36° angle THX recommends gives about 86 inches, so 80–90 inches is comfortable and up to about 100 inches if you prefer immersion.
- What screen size do I get 3 m from the wall?
- With a 1.2–1.5 throw ratio, about 90–113 inches in 16:9. With a fixed 1.2 throw ratio (no zoom), about 113 inches. If you need a smaller image without zoom, move the projector forward or use digital zoom (which reduces the pixels used).
- Where does the image sit with a ceiling mount?
- Ceiling-mounted projectors are upside down, so the image appears below the lens by the offset. At 100% offset the top of the image is at lens height. With a 240 cm ceiling, the lens at 215 cm and a 100-inch image (about 125 cm tall), the image runs from about 90 to 215 cm above the floor.
- How many lumens do I need to watch in a bright room?
- For a 100-inch 16:9 image on a 1.0 gain screen, assuming 80% of the rated brightness: about 540 ANSI lumens for a dark room (50 cd/m²), about 1,100 for indirect lighting only (100 cd/m²) and about 2,200 with the lights on (200 cd/m²). Projectors rated in LED lumens are roughly 1/2.4 of that figure in ANSI lumens.
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