🌫️ ND Filter Calculator
Pick your metered shutter speed and the ND filter strength to get the new long-exposure shutter time.
New shutter time with the ND filter
17.1 s
10 stops = ×1,024 longer
A neutral-density filter cuts light so you can use a longer shutter for motion blur (silky water, cloud streaks) in daylight. Each stop doubles the exposure time, so new time = metered time × 2^stops — a 10-stop ND (ND1000) turns 1/60 s into about 17 seconds. Beyond ~30 s you\'ll need bulb mode and a remote. 🔒 In your browser.
How the nd filter calculator works
A neutral-density (ND) filter darkens the whole scene evenly so you can use a much longer shutter in bright light — for silky water, streaking clouds or empty-looking streets. Every "stop" of ND doubles the exposure time, so the new time is your metered time × 2^(stops). A 10-stop ND (often sold as ND1000) multiplies the exposure by 1,024: a metered 1/60 s becomes about 17 seconds. Choose your base shutter and the filter strength and the tool gives the new time.
Meter and focus first without the filter, then attach it (strong NDs make autofocus and viewfinders go dark). Once the calculated time passes about 30 seconds — the usual longest standard setting — switch to bulb mode with a remote or intervalometer, and use a tripod. Stacking filters adds their stops together.
Frequently asked questions
How do I calculate shutter speed with an ND filter?
Multiply your metered shutter time by 2 raised to the number of stops: new time = base × 2^stops. A 6-stop ND on a 1/8 s exposure gives 1/8 × 64 = 8 seconds.
How many stops is an ND1000 filter?
ND1000 is a 10-stop filter (2^10 = 1024, so it cuts light by about 1,000×). It turns a 1/60 s exposure into roughly 17 seconds — ideal for daytime long exposures of water and clouds.
What ND filter do I need for long exposures?
For visibly smoothing water or clouds in daylight you usually want 6 to 10 stops. A 10-stop is the classic choice for multi-second daytime exposures; 3–6 stops suit brighter blur or slightly dimmer light. Enter the stops to see the resulting time.
Can I stack ND filters?
Yes — stacking adds their stop values (a 6-stop plus a 3-stop gives 9 stops). Watch for vignetting on wide lenses and some loss of image quality with cheaper filters. Add the total stops in this calculator.
Why does my long exposure need bulb mode?
Most cameras' longest standard shutter is 30 seconds. When the ND math gives a longer time, you must use bulb mode and time the exposure with a remote or intervalometer, keeping the camera on a tripod throughout.