Shutter Speed Calculator
Solve for shutter speed when aperture and ISO are set. Results update live.
Inputs
Press Calculate to update results as you change values.
Results
Solving for shutter speed
When depth of field dictates aperture and noise limits ISO, shutter speed is what remains to hit a target exposure. This calculator outputs both a reciprocal fraction (1/250, 1/1000) and the raw time in seconds so you can set mechanical or electronic shutters accurately.
Use it together with the reciprocal rule calculator to check whether the required speed is still safe for handheld shooting at your focal length.
Formula
Example
EV 12, f/4, ISO 100 → t = 0.01 s → 1/100 s.
FAQ
How do I write very long exposures?
Times over one second are shown in seconds. Use bulb mode, a remote release and consider long-exposure noise reduction.
Does this account for ND filters?
An ND filter reduces light by a fixed number of stops. Subtract that many stops from your target EV (or multiply time by 2^stops) after reading the unfiltered result.
Motion, blur and safe speeds
Once you know the shutter the exposure equation demands, compare it with the reciprocal rule for your focal length. If the equation wants 1/30 s but you are handheld at 85 mm on full frame, expect shake unless stabilization or a brace saves you. Raise ISO or open aperture until the required shutter climbs into a safer range. Panning shots invert the logic: you may want a slower shutter on purpose; use the calculator to keep overall EV correct while you dial blur.
Long-exposure landscape shooters can solve for multi-second times, then add ND filter stops by doubling time for each stop of density. The tool keeps the base exposure honest before filters enter the chain.