Enter your base shutter speed and ND strength. The calculator outputs both the exact time and a rounded value to the nearest standard shutter speed.
Exposure time doubles for each stop. Rounding uses the nearest common shutter speed value. Long exposures display in seconds or minutes.
What is a stop? One stop equals a doubling (or halving) of exposure time.
Can I stack filters? Yes. Add the additional stops in the stacked field to combine filters.
Why is rounding different? Real cameras use discrete shutter speeds; we choose the closest standard value.