Screen & projection

Throw distance, brightness and seating distance for your room – including lens shift, AT fabric and scope via zoom or lens.

Sample values. Enter your own – they are stored in this browser only.

Room
Screen
Enter size as

Acoustically transparent fabric absorbs light. Solid screen: 0 %. Check the manufacturer’s figure.

Projector

Spec-sheet lumens are usually well above calibrated output. We therefore prefill 70 % of the rated figure – a rough assumption, not a standard. Every value can be overridden.

Throw ratio = distance ÷ image width. Manufacturers measure from the lens front or from the chassis – check the spec sheet.

Scope method

Zoom: the 16:9 image is zoomed to fill the screen width. Light falling on the bars above and below is wasted.

Positive = right of screen centre (facing the screen).

In % of image height/width, as on the spec sheet. Leave empty if unknown.

Seat
Save & share room

On-screen brightness
31.2fL107 nitsHDR headroom

Screen

Width
3.00 m
Height
1.28 m
Diagonal
128″ · 326 cm
Image area
3.83 m²
Lit area
5.06 m²
Light in image
76 %

Throw distance

Minimum
4.05 m
Maximum
8.52 m
Chosen
5.00 m
Throw ratio there
1.67:1

The chosen distance is within the zoom range.

Seating

Horiz. viewing angle
43.1°
SMPTE 30°
5.60 m
THX 36°
4.62 m
40°
4.12 m

Above 40°: very close, you will turn your head to follow the edges.

Lens shift

Required vertical
-57 %
available
± 90 %
Required horizontal
0 %
available
± 40 %

Reachable with the available lens shift.

Positive = image above / right of the lens axis.

Top view, to scale
0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m4.05 m – 8.52 mSMPTETHX3.80 m
ScreenProjector & zoom rangeSeat & viewing angle
Side view, to scale
0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m0.60 m2.20 m
projected 16:9 image

How it works

Lumens are not brightness

What you see is luminance on the screen. It depends on the projector’s light output, the lit area and the screen gain:

nits = lumens × gain × (1 − fabric loss) × (1 − lens loss) ÷ (π × area in m²)

One foot-lambert (fL) equals 3.426 nits. The formula assumes a perfectly diffusing screen; gain describes how far the real screen departs from that on axis. High-gain screens get dimmer off-centre, which this calculator does not model.

Use a calibrated figure. Spec-sheet lumens are usually measured in the brightest picture mode and tend to sit well above what is left after calibrating to D65. When you pick a projector from the list we prefill 70 % of the rated output – a rough assumption. If you have a measurement, enter it.

Brightness rating

fLnitsMeaning
below 12below 41too dim, flat picture
12–1641–55SDR cinema reference (dark room)
16–2455–82bright SDR with some headroom
24 and up82 and upheadroom for HDR tone mapping

These limits are guidance, not rules. The 14 fL cinema reference (48 cd/m², tolerance ±3.5 cd/m²) is set by SMPTE ST 431-1 for digital cinema projection. There is no fixed target for projected HDR – more light simply gives tone mapping more room.

AT fabric

Acoustically transparent screens let sound through perforations or a weave, and lose light in the process. Manufacturers quote anything from a few percent to over 20 % – take the figure from your fabric’s spec sheet.

Scope: zoom or anamorphic lens

Almost every projector has a 16:9 panel. For a scope screen (2.35:1 to 2.40:1) you have two options. Zoom: enlarge the 16:9 image until the film fills the screen width; the black bars land above and below the screen, taking about 24 % of the light at 2.35:1 with them. Anamorphic lens: the projector stretches the image vertically across the whole panel and the lens widens it again. All panel pixels and all the light end up on screen, minus the lens’s own loss, which you can enter. Note that throw ratio then refers to the unstretched image width (image height × 16/9), so the projector can sit closer.

Throw distance and lens shift

Distance = throw ratio × image width. Manufacturers measure from the lens front or from the chassis, so leave some margin.

Lens shift moves the image without keystone distortion. The calculator works out how far the image centre sits from the lens axis, as a percentage of projected image height or width – the way most spec sheets state it. With scope via zoom, the full 16:9 image height counts. Many projectors cannot use full vertical and horizontal shift at the same time; the calculator applies a simple diamond-shaped check. Your spec sheet has the real limits.

Seating distance

Horizontal viewing angle = 2 × arctan(image width ÷ 2 × distance). Two figures come up again and again: the 30° minimum goes back to SMPTE EG 18-1994, which SMPTE withdrew in 2003. THX advises cinema designers to plan for 36° from the farthest seat, and THX’s rule of thumb for TVs (diagonal = 0.835 × seating distance) works out at about 40° for 16:9. Many enthusiasts sit closer for scope. There is no single right answer – resolution, seating rows and taste all play a part.

FAQ

How do I convert lumens to nits or foot-lamberts?

Luminance (nits, cd/m²) = lumens × gain × (1 − fabric loss) ÷ (π × lit area in m²). One foot-lambert is 3.426 nits. Use a calibrated, measured lumen figure rather than the spec sheet.

How bright should a home cinema image be?

For SDR films in a dark room, roughly 14 to 16 fL (about 48 to 55 nits) is the usual cinema reference. Extra brightness helps HDR tone mapping. Below 12 fL the picture looks flat.

Zoom or anamorphic lens for a scope screen?

Zooming leaves the 16:9 panel as it is and throws the letterbox bars onto the masking – about a quarter of the light at 2.35:1. An anamorphic lens uses the whole panel but costs a few percent of light itself, and money.

What is the right seating distance?

Commonly quoted guidelines are a horizontal viewing angle of at least 30° (from SMPTE EG 18, withdrawn in 2003) and 36 to 40° (THX). The calculator shows the matching distances for your screen width.