OneTool

ND Filter Shutter Speed Calculator

Long-exposure math for ND2 through ND1000 filters.

Mode
  • Shutter with filter

    8.2s

  • Filter strength

    10 stops (~1024× light reduction)

What is this tool?

A neutral-density filter cuts light in stops — ND8 is 3 stops (8× less light), ND1000 is about 10 stops — so each stop doubles your exposure time. Meter without the filter, pick your ND strength, and this calculator gives the equivalent long-exposure shutter speed. Reverse mode takes your metered speed and the shutter speed you want (say, 30 seconds for silky water) and tells you how many stops of ND you need plus the closest common filter.

How to use it

  1. Meter the scene without the filter and enter that base shutter speed.
  2. Pick your ND filter strength, or switch modes and enter a desired shutter speed.
  3. Read the new exposure time, or the ND stops and closest filter to buy/stack.