ND Filter Exposure Calculator
Instantly find the new shutter speed for your long exposure shot.
Tip: 1/1000s is 0.001, 1/8s is 0.125, 1s is 1.
Calculated Long Exposure Time
Final Shutter Speed:
(Calculation: 1s base × 10 stops)
Error:
Please enter a positive value for the base shutter speed.
The Essential Guide to Neutral Density (ND) Filters
You’ve likely come across breathtaking images where waterfalls look like silk or clouds appear smeared across the sky. These effects are the signature of long exposure photography, and they are only possible thanks to Neutral Density (ND) Filters.
Think of an ND filter as a pair of sunglasses for your camera lens. It doesn't change the color (it's "neutral"), but it drastically reduces the amount of light that hits your camera's sensor. This forces you to use a much slower shutter speed than you normally would, even in bright daylight.
Why the Calculator is Essential
In normal light, your camera might determine that a correct exposure requires a shutter speed of 1/125 of a second. If you want to smooth out a river, you might need an exposure of 30 seconds.
If you add a strong filter—like a popular 10-stop ND filter (ND1000)—you need to multiply your original shutter speed by a huge factor. This math is tedious and prone to error in the field, especially when dealing with exposures that last several minutes.
That’s where this calculator steps in. It takes your base exposure and your filter's strength, and instantly provides the final, correct, long-exposure time, often converting milliseconds into clean minutes and seconds.
Understanding the Math: The Power of Stops
A "stop" in photography refers to a doubling or halving of the light. Every time you increase the strength of your ND filter by one stop, you double the required exposure time.
The formula the calculator uses is based on this simple exponential relationship:
Tnew=Tbase×2N
Where:
Tnew is the New Exposure Time (what you need to set on your camera).
Tbase is the Base Exposure Time (what your camera metered without the filter).
N is the number of Stops your ND filter provides.
For example, if your base speed is 1 second and you use a 10-stop filter (N=10):
The factor is 210=1024.
The New Exposure Time is 1 second×1024=1024 seconds, or 17 minutes and 4 seconds.
The power of the calculator is converting that 1024 seconds into a human-friendly format instantly.
How to Use the ND Filter Calculator
Input Your Base Speed: Meter your scene without the ND filter attached. Take note of the shutter speed needed for a correct exposure (e.g., 1/30s or 4s). Enter this as a decimal in the calculator (e.g., 1/30s is 0.033).
Select Your Filter: Choose the strength of the filter you plan to use (e.g., 6 Stops, 10 Stops, or 13 Stops).
Read the Result: The calculator instantly shows the new, correct shutter speed required to achieve the same exposure level, but now with that dreamy long-exposure look.