Case 1
- Aperture as f-number
- 4
- Shutter speed
- 0.0625s
8.0000EV
Open with these valuesExposure Value Calculator
8.0000EV
Result: 8.0000 EVExposure value squeezes aperture and shutter speed into one number: EV = log₂(N² ÷ t). One whole EV is one stop, a halving or doubling of the light. Many settings share an EV — f/4 at 1/16 s, f/8 at 1/4 s and f/16 at 1 s are all EV 8.
Worked examples
Case 2
- Aperture as f-number
- 8
- Shutter speed
- 0.004s
13.9658EV
Open with these valuesCase 3
- Aperture as f-number
- 1.4
- Shutter speed
- 30s
-3.9360EV
Open with these valuesHow it's calculated
EV = log₂(N² ÷ t)
- StepEnter the aperture as a plain f-number, such as 2.8, 4 or 8.
- StepEnter the shutter speed in seconds as a decimal — 1/250 s is 0.004.
- ResultRead the exposure value; each whole step is one stop of light.
Reference table
| F-number, shutter speed in s | Setting | Exposure value |
|---|---|---|
| 1.4, 30 | f/1.4 for 30 s, night sky | -3.9360 |
| 5.6, 0.5 | f/5.6 at 1/2 s | 5.9709 |
| 2.8, 0.0625 | f/2.8 at 1/16 s | 6.9709 |
| 4, 0.0625 | f/4 at 1/16 s | 8 |
| 8, 0.25 | f/8 at 1/4 s, same exposure | 8 |
| 16, 1 | f/16 at 1 s, same exposure again | 8 |
| 8, 0.004 | f/8 at 1/250 s, bright sunlight | 13.9658 |
Questions
How do I calculate exposure value?
Square the f-number, divide by the shutter speed in seconds, and take the base-2 logarithm. At f/4 and 1/16 s that is log₂(16 ÷ 0.0625) = log₂(256) = 8 EV.
What is exposure value?
It is a single number combining aperture and shutter speed to describe how much light reaches the sensor. Each whole EV is one stop, a halving or doubling of the light, which makes settings easy to compare and trade off.
How do I enter the shutter speed?
As a decimal in seconds, not as a fraction. A 1/250 s speed is 0.004, 1/125 s is 0.008 and 1/16 s is 0.0625. To convert a fraction 1/x, divide 1 by x.
Why do different settings give the same EV?
Because EV measures the total light, and aperture trades against shutter speed. The table above shows three pairings that all land on EV 8, and that trade is the basis of the exposure triangle.
Does exposure value include ISO?
No. By convention EV is defined at ISO 100 and depends only on the aperture and the shutter speed. To match a real scene you combine it with the metered light level and any ISO offset.
Sources and last check
Information, not professional advice.