Exposure Value EV Calculator
Free Exposure Value EV Calculator for creative & design. Free online tool with accurate results using verified formulas.
Formula
EV = log2(N^2 / t) where N = f-number, t = shutter speed in seconds
EV is the base-2 logarithm of the ratio of the aperture squared to the shutter speed. Each integer EV step represents a doubling or halving of light. ISO adjustments add log2(ISO/100) to the base EV100 value.
Worked Examples
Example 1: Sunny Day Outdoor Exposure
Problem: Calculate the EV for a sunny day shot at f/8, 1/250s, ISO 100.
Solution: EV100 = log2(f^2 / t)\nEV100 = log2(8^2 / (1/250))\nEV100 = log2(64 * 250)\nEV100 = log2(16000)\nEV100 = 13.97\nApprox illuminance = 2.5 * 2^14 = 40,960 lux
Result: EV = 13.97 at ISO 100, typical of a hazy bright day.
Example 2: Indoor Portrait with Available Light
Problem: A portrait is shot at f/2.8, 1/60s, ISO 800. What is the EV100?
Solution: EV100 = log2(2.8^2 / (1/60))\nEV100 = log2(7.84 * 60)\nEV100 = log2(470.4)\nEV100 = 8.88\nEV at ISO 800 = 8.88 + log2(800/100) = 8.88 + 3 = 11.88\nScene luminance ~ 2^8.88 * 2.5 / pi = 373 cd/m2
Result: EV100 = 8.88 (bright indoors), EV at ISO 800 = 11.88.
Frequently Asked Questions
What is Exposure Value (EV) in photography?
Exposure Value is a number that represents a combination of camera aperture and shutter speed settings that produce the same overall exposure. An EV of 0 corresponds to an aperture of f/1.0 with a 1-second shutter speed at ISO 100. Each increment of 1 EV represents a doubling or halving of the light captured. EV 15 corresponds to bright direct sunlight while EV 5 might represent typical indoor lighting. Photographers use EV to quickly communicate lighting conditions and to determine equivalent exposure settings. The concept was introduced in the 1950s by the German shutter manufacturer Friedrich Deckel to simplify exposure calculations when light meters gave readings in EV units.
How does ISO affect the Exposure Value calculation?
In the standard EV formula, EV is calculated at ISO 100 as the base sensitivity. When you change the ISO, you effectively shift the required EV. Doubling the ISO (e.g., from 100 to 200) adds 1 to the EV, meaning you need one stop less light from the aperture and shutter combination. The ISO-adjusted formula is EV = EV100 + log2(ISO/100). For practical shooting, a higher ISO lets you use faster shutter speeds or smaller apertures in the same lighting. However, higher ISO values introduce more digital noise or film grain, so photographers balance ISO adjustments against image quality. Modern cameras handle high ISO remarkably well, with usable results often up to ISO 6400 or beyond.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
How accurate are the results from Exposure Value EV Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Is Exposure Value EV Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.