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Projection

Cinema screen brightness calculator

Will this projector light that screen? Enter the light output, the screen and its gain, and the losses in the path; the calculator gives the brightness at screen centre and what you would need for the 2D reference.

Projector and screen

Matte white ≈ 1.0; silver 3D screens ≈ 1.8–2.4.
0 for 2D. Polarising and shutter systems commonly lose well over half.

Result

Brightness at screen centre—

—

—

Lumens needed for 14 fL—

With the same screen, gain and losses.

Estimate for screen centre. Confirm with a spot-meter reading. Runs in your browser.

Everything here runs in your own browser. No values are sent to us, nothing is stored, and there is no sign-up.

How it is calculated

Screen luminance in foot-lamberts is the light reaching the screen, in lumens, multiplied by the screen gain and divided by the screen area in square feet. One foot-lambert is 3.426 nits. The DCI reference for 2D is 14 fL at screen centre; see foot-lambert and laser projection.

It is an estimate: real rooms lose light unevenly, and a spot-meter reading at screen centre is the number that counts.

Answers

Frequently asked questions

How many lumens do I need for a cinema screen?

Enough to reach about 14 foot-lamberts at screen centre after losses. For a matte white screen (gain 1.0) that is roughly 14 lumens per square foot of screen, plus whatever the port glass, lens and 3D system absorb.

How do I convert foot-lamberts to nits?

Multiply by 3.426. The 14 fL cinema reference is about 48 nits.

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