ND Filter Exposure Calculator
ConvertEverything runs locally in your browser — nothing is uploaded
ND stops are powers of two: the 1000 in ND1000 is only a name, and 10 stops is 2^10 = 1024 times. The number of stops is what actually drives the exposure, so this tool works in stops and explains where the model name and the real factor differ. ⚠️ Stacking several filters adds their stops (two ND8 filters are 6 stops, 64 times), rather than multiplying the model numbers. ⚠️ The result is rounded to a shutter speed that exists on a camera — there is no 3.7 s step, so the nearest standard step is given along with the exact value. Everything runs in your browser.
Features
- Converts in stops: ND1000 is 10 stops, 2^10 = 1024 times
- Built-in ND2, ND4, ND8, ND16, ND32, ND64, ND100, ND1000 and ND100000, plus custom stops
- Stacked filters add their stops, with the total factor shown
- Rounds to the standard shutter steps and gives the exact value separately
- Shows the working, such as `1/250 -> 1 s`
- Optional time-lapse interval and total shooting time
- Understands `1/250`, `0.004` and `2` as shutter speeds
- Everything runs locally and nothing is uploaded
How to use
- Enter the current shutter speed, for example `1/250` or `0.004`
- Pick an ND filter, or choose Custom and enter the stops
- Set the number of filters to 2 if you stack two
- Tick the time-lapse box for the interval and total time
FAQ
- Is ND1000 ten stops or a thousand times?
- Ten stops, which is 2^10 = 1024 times. The 1000 is a manufacturer name rather than an exact factor. Likewise ND100 is 6.6 stops (about 97 times) and ND100000 is 16.6 stops (about 100,000 times). Conversion goes by stops, and half a stop off means a brighter or darker frame.
- How do two stacked ND filters combine?
- Their stops add. Two ND8 filters are 3 stops each, so 6 stops and 64 times together. Writing 8 x 8 = 64 happens to work, but combining an ND8 with an ND1000 gives 3 + 10 = 13 stops (8192 times) while multiplying the names would give 8000, which is wrong.
- Why is the result not exact?
- Because cameras only offer fixed shutter steps (one third of a stop each) and have no 4.096 s setting. The tool gives the nearest standard step and writes the true result on the Exact value row, so you can enter it yourself on a camera with bulb mode or fractional seconds.
- Where does the time-lapse interval come from?
- The exposure of each frame cannot exceed the interval, so the interval is at least the shutter speed. The example assumes a 10 second clip at 30 fps (300 frames) and gives the interval and total shooting time; substitute your own length and frame rate.
Related tools
Crop Factor
ConvertCrop factor from the sensor diagonal, equivalent focal length, horizontal, vertical and diagonal angles of view, plus a depth-of-field estimate.
Motion Blur Calculator
ConvertTwo safe-shutter figures, the motion blur in pixels at a given shutter, and the shutter needed to freeze a moving subject, from focal length and speed.
HDR Bracketing
ConvertFrom the scene range and the camera range, work out how many frames to bracket, each exposure compensation, the total coverage and whether it is enough.
Timestamp Converter
ConvertConvert Unix timestamps into dates and back, telling seconds, milliseconds, microseconds and nanoseconds apart, with Windows FILETIME and decimals.
Date Calculator
ConvertCount the days, weeks or months between two dates, or shift a date by any of those. Dates can be picked from a calendar or pasted in — nothing is uploaded.
Number Base Converter
ConvertConvert numbers between binary, octal, decimal, hex, base 36 and base 64, with long IDs converted digit for digit. Runs in your browser.