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HDRI Exposure Calculator

3D Artist Match an HDRI to a target camera exposure
Target Exposure
Desired EV (at ISO 100)11.0
The look you are lighting for. EV 11 is a bright soft interior, EV 15 is harsh daylight.
ISO
Aperture (f-stop)
Shutter speed
Reference cross-check only (shown in Stops Math). The multiplier follows your target EV and ISO.
HDRI base EV (as shot)8.0
Roughly what the HDRI was captured at. Most studio and indoor HDRIs sit near EV 6 to 9; outdoor maps EV 12 to 15. Adjust if known.
Recommended HDRI Multiplier
-x
linear intensity multiplier on the environment
Stops to add
-
Scene EV
-
Set the environment intensity to - to hit your target.
Stops Math
Camera target EVat the ISO you selected
-
From aperture + shutter (ISO 100)EV = log2(N squared / t)
-
HDRI base EV (as shot)
-
Difference to correcttarget minus base
-
Multiplier = 2 ^ stops
-
EV 2 - nightEV 17 - bright sun
How to apply it per engine
Keyshot
Environment brightness
-
Cinema 4D
Sky / HDRI strength
-
Blender
World strength
-
What this does

Photographic exposure is measured in stops. Each stop doubles or halves the light. Exposure value EV = log2(N squared / t) at ISO 100, where N is the f-number and t is the shutter time in seconds. Raising ISO lowers the EV your camera needs by one stop per doubling.

To make an HDRI read at your target look, you scale its intensity by 2 to the power of the stop difference between the target EV and the EV the HDRI was captured at. One stop brighter is a 2x multiplier, two stops is 4x, one stop darker is 0.5x.

This is a linear multiplier, so apply it before any tone mapping or view transform (Filmic, AgX, ACES). If you change the camera f-stop, shutter or ISO inside the render engine, re-run the numbers, the environment multiplier is relative to the exposure you set.

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