Exposure Value (EV) Calculator

Exposure value (EV) is a single number that summarizes how much light reaches the sensor for a given aperture, shutter speed, and ISO combination, using the APEX system: EV = log₂(N² / t) − log₂(ISO / 100), where N is the f-number and t is the shutter speed in seconds.

Many different aperture/shutter/ISO combinations can produce the same EV and therefore the same overall exposure — this is the basis of the "exposure triangle." Each full stop change in any one setting shifts EV by exactly 1.

Example: the classic "Sunny 16" rule (f/16, 1/125s, ISO 100) works out to EV ≈ 14.97, a typical value for bright daylight. Opening up to f/8 at the same shutter speed and ISO drops EV to about 12.97 — 2 stops brighter, since f/16 to f/8 is a 2-stop change in aperture.

Each EV step doubles or halves exposure — changing aperture one stop or shutter one stop shifts 1 EV.

Exposure compensation on camera dial adjusts meter target by EV — same math as manual offset here.

EV pairs help compare settings across scenes when balancing aperture, shutter, and ISO manually.

Sunny 16 (EV ~15 at ISO 100, f/16, 1/125s) is a field sanity check — if your meter reads EV 10 in full sun, check lens cap, ISO setting, or meter calibration before trusting automatic exposure. Sunny 16 near EV 15 at ISO 100 sanity-checks meters — EV 10 in full sun suggests cap, ISO, or calibration errors before shooting.

Bracketing HDR landscapes often spans ±2 EV — three shots at EV 12, 14, and 16 merge shadow and highlight detail when single-shot dynamic range fails on backlit ridges. HDR brackets at ±2 EV merge shadow and highlight detail when single shots clip ridgelines against bright sky at default ISO 100 settings. Capture ±1 EV brackets when HDR deliverables need merged shadow detail beyond a single EV reading.

At f/8, 1/125s, ISO 100, EV ≈ 13 on this calculator's APEX model — opening one stop to f/5.6 without changing shutter or ISO raises scene brightness one EV, equivalent to doubling light. f/8, 1/125 s, ISO 100 → EV ≈ 13 — open to f/5.6 without changing shutter or ISO adds one stop, doubling light on the sensor.