Projector Screen Calculators
Enter your room once. Every tool below uses the same numbers, so you can see the view from your seat, check brightness, and find screens that fit.
Your room
Measure from your eyes to the screen wall.
The seat view is in a floating window. It keeps updating as you change anything on the page.
What the lines mean
- Easy glance (inner ring, ±15°). Everything inside it is seen with small eye movements. Your head stays still.
- Eye limit (outer ring, ±30°). Your eyes can reach this far comfortably. Anything outside it needs a head turn.
- SMPTE 30° outline. The screen size that fills 30° from this seat, the low end of the recommended range.
- THX 40° outline. The screen size that fills 40° from this seat, the THX best-seat size.
- IMAX 55° outline. The screen that fills 55° from this seat, an IMAX-style wall of picture.
- Sight lines. From your eyes to the corners of the screen.
- Grid. 1 ft squares on the floor and screen wall, for scale.
Screen size
Enter any one measurement of the viewable area. The others fill in, and every other tool updates.
Where to sit for this screen
What size for your seat
Brightness
The seat view, with your projector, screen and room light. Change anything below and watch the picture brighten, dim or wash out.
Brightness on the screen depends on the projector's light, the screen size and the screen's gain. Rated lumens are a best case, measured in the brightest mode with the zoom at its widest.
Compare sizes
Compare any two sizes side by side, like the 85″ TV you have now and the 120″ screen you're considering. Both are drawn to scale next to a person.
Display A
Display B
Throw distance
Pick a projector, or enter the throw ratio from its spec sheet. Throw ratio is the distance from the lens to the screen divided by the image width.
Where you plan to mount it, measured from the lens to the screen. Leave it anywhere if you don't know yet.
Lenses for this projector
Lens shift
Lens shift moves the image without moving the projector. On most projectors the two directions share one range: shifting sideways takes away vertical shift, and the other way around. Move the sliders to see how much is left.
Left: the shared shift range; the dot is your setting. Right: where the lens can sit on the wall. Green is the vertical shift still available, orange the sideways shift still available.
Compare projectors
See how brightness and contrast change the picture on your screen, in your room. Both projectors use the screen, surface and room light set above and in the Seat view.
Projector A
Manufacturer's rated contrast (not used in the simulation)
Projector B
Manufacturer's rated contrast (not used in the simulation)
Why three contrast numbers?
Dynamic contrast is the number most spec sheets lead with. It compares an all-white frame to an all-black frame with the auto iris or laser dimming working, so the projector gets to change its light output between the two. It shows what the dimming can do, not what you see within one picture, and it can't be converted to the other two numbers.
Native (sequential) contrast, also called on/off contrast, is the same full-white vs full-black test with the iris fixed and laser dimming off. It's the projector's real capability, and it decides how black a dark scene looks.
ANSI contrast is measured on a 4×4 checkerboard of white and black squares in one picture. Light scattering in the lens and bouncing off the room lifts the black squares, so it's always much lower. For example, a projector rated 1,000,000:1 dynamic might measure around 5,000:1 native and only 100–200:1 on the checkerboard.
The simulation uses native and ANSI contrast. The manufacturer rating is shown for reference only.
Conversions
Type in any box and the others update.
Screen brightness
1 ftL = 3.426 nits. SDR targets are about 14–16 ftL (48–55 nits) in a dark room. HDR projectors often reach 100–250 nits.
Room light
1 fc = 10.764 lux. A light meter or phone app usually reads lux. Dim lamps put about 1–5 fc on a screen; a lit living room, 10–30 fc.
Length
Lumens to screen brightness
ftL = lumens × gain ÷ screen area in square feet. Type a target ftL or nits to see the lumens you'd need. Starts with the screen in Your Room.
Throw ratio
Distance = throw ratio × image width. Change any box and the one you touched least recently updates.
Same height, different shape
Contrast ratio
Each photographic stop doubles the range: 1,024:1 is 10 stops, about 32,768:1 is 15. Use native (sequential) contrast, not dynamic.
Viewing angle
SMPTE recommends at least 30°, THX 36–40°. Type an angle to see the seat distance for your width.
Save your theater
Free to use. Add your email to save this setup, come back to it later, and get a copy of your renderings.
