ND Filter Calculator

Enter your base exposure and pick an ND filter. Get the new shutter speed instantly. Stack multiple filters and see the combined effect.

New Shutter Speed
1/125s
Base: 1/2000s — gaining 4 stops with ND16
// Base Exposure
Stacked filters
// Select Primary Filter
// Common use cases
🌊
Silky waterfalls
Need 1–3s at daylight — use ND64 to ND1000
🎬
Video 180° rule
Shutter = 2× frame rate. At 25fps: 1/50s. Use ND to match.
✨
Light trails
30s+ at dusk — usually no ND needed, wait for dark

// how ND filters work

An ND (Neutral Density) filter reduces the amount of light entering the lens without affecting colour. The number (ND2, ND4, etc.) tells you the light reduction factor. ND2 = 1 stop, ND4 = 2 stops, ND8 = 3 stops, ND16 = 4 stops, ND64 = 6 stops, ND1000 = 10 stops.

Stacking filters multiply their values — ND8 + ND64 = ND512 (9 stops total). Be aware of vignetting and colour cast with thick filter stacks, especially on wide-angle lenses.

The 180° shutter rule in video: your shutter speed should be roughly double your frame rate (24fps → 1/48s, 25fps → 1/50s, 30fps → 1/60s). In daylight you'll almost always need an ND to achieve this without overexposing.