Exposure Value Calculator (LV / EV).
Calculate light values (LV) and exposure values (EV) from aperture, shutter speed and ISO – precise exposure metering with the APEX system.
Ideal for planning images without a light meter, judging mixed light or comparing exposures between cameras.
- ◆APEX system
- ◆With scale
- ◆Equivalents
- ◆Mobile friendly
Exposure Value Calculator (LV/EV)
Calculate light values and exposure values from aperture, shutter speed and ISO
Exposure parameters
Current: 1/125 | Examples: 1/125s = 125, 2s = 0.5
Calculation basis:
- • LV: (2×ln(aperture) − ln(shutter reciprocal)) ÷ ln(2)
- • EV: LV + log₂(ISO ÷ 100)
- • Standardised exposure metering
- • APEX system (Additive System of Photographic Exposure)
Results
Important notes:
- • LV (Light Value) = light value at ISO 100
- • EV (Exposure Value) = exposure value with the current ISO
- • Higher values = more light required
- • Each stop = factor of 2 in the amount of light
- • Standard for exposure metering and automation
Understand light values and put them to use.
Light values (LV) and exposure values (EV) are standardised measures of scene brightness and the matching camera settings. They are based on the APEX system of photography.
What the letters mean.
LV (Light Value): light value at ISO 100
EV (Exposure Value): exposure value with the current ISO
- At ISO 100: LV = EV
- At ISO 200: EV = LV + 1
- At ISO 400: EV = LV + 2
- At ISO 50: EV = LV − 1
What the calculator helps with.
- Precise exposure metering without a light meter
- Comparison of different exposure settings
- Understanding camera auto modes
- Assessing light situations
- Documenting shooting conditions
Typical LV values: 15 bright sunny day · 12 overcast day · 8 dusk · 4 indoor lighting · 0 moonlight.
The mathematical foundation.
Two formulas carry everything – one for the pure light value, one for the ISO adjustment that yields the exposure value.
f/5.6 · 1/125s · ISO 200
LV = (2 × ln(5.6) − ln(125)) ÷ ln(2) = 9.6
EV = 9.6 + log₂(200 ÷ 100) = 9.6 + 1 = 10.6
EV values and light situations.
A compact reference for placing any scene roughly on the scale – including example settings at ISO 100.
| EV value | Light situation | Example setting (ISO 100) |
|---|---|---|
| −4 to −2 | Starry sky, very dark night | f/1.4 · 30 s |
| −1 to 1 | Moonlight, faint street lighting | f/2.8 · 8 s |
| 2 to 4 | Living room, office lighting | f/2.8 · 1/30 s |
| 5 to 7 | Overcast day in the shade | f/5.6 · 1/60 s |
| 8 to 11 | Overcast to lightly overcast day | f/8 · 1/125 s |
| 12 to 15 | Sunny day, bright day | f/11 · 1/250 s |
| 16+ | Snow, sand, water reflections | f/16 · 1/500 s |
Five hints for better exposure metering.
The standardised exposure system.
APEX (Additive System of Photographic Exposure) describes exposure parameters using logarithmic values – which makes the whole system addable.
The five abbreviations.
- Av: Aperture Value
- Tv: Time Value
- Sv: Speed Value (ISO)
- Bv: Brightness Value
- Ev: Exposure Value
Why addition instead of multiplication.
- Simple addition/subtraction instead of multiplication
- Universal comparability of exposures
- Foundation for modern auto-exposure
- Precise exposure compensation in stops
Answers to common questions.
Related tools.
These calculators match the current tool and extend your workflow.
Solid photography knowledge.
Calculators give you the number. On the blog and in 1:1 coaching I turn theory into results you can see in your images.