Shutter Speed ↔ Frame Rate (180° Rule)

Convert between shutter angle and shutter speed at any frame rate, snap to the 180° rule, and check flicker-safe speeds for 50Hz or 60Hz lighting live as you type.

Frame Rate & Mode

Frame rate (fps)

Mode

Shutter angle (°)

Region mains frequency

Reference

The 180° rule sets shutter speed to twice the frame rate for natural, film-like motion blur — e.g. 1/48 at 24fps. Smaller angles (90°, 45°) give a sharper, more staccato look; larger angles (270°, 360°) add heavier blur.

Flicker safety: under mains-powered lighting, shutter speeds that aren’t a multiple of the mains half-cycle can cause visible banding. Pick your region above to see the nearest safe speeds.

Results

Nearest Flicker-Safe Shutter Speeds

The 180-Degree Rule and Flicker-Safe Shutter Speeds

Shutter speed and shutter angle are two ways of describing the same thing: how long each frame is exposed. Shutter angle is a film-era concept inherited from rotary shutters — a 180° angle exposes the frame for half of each frame duration, regardless of frame rate. Shutter speed is the same exposure expressed directly in seconds. Because the relationship depends on frame rate, the same shutter angle produces a different shutter speed at 24fps than it does at 60fps.

The Shutter Speed ↔ Frame Rate tool converts between the two instantly at any frame rate, checks your result against the 180° rule, and flags whether your shutter speed is safe from banding under mains-powered lighting.

The 180° Rule

Setting shutter speed to twice your frame rate — a 180° shutter angle — produces the natural, cinematic motion blur audiences expect. At 24fps that’s 1/48 second; at 30fps it’s 1/60. Smaller angles like 90° or 45° produce sharper, more staccato motion (think the beach landing in Saving Private Ryan), while larger angles like 270° or 360° smear motion into a dreamier, more surreal look.

Flicker Safety Under Mains-Powered Lights

Fluorescent, LED, and HMI fixtures powered by AC mains actually pulse at twice the mains frequency — 100 times a second at 50Hz, 120 times a second at 60Hz. If your shutter speed isn’t a multiple of that pulse cycle, you’ll capture a different point in the brightness cycle on every frame, showing up as visible flicker or rolling bands in the footage. The tool checks your shutter speed against your region’s mains frequency and lists the nearest speeds that stay in sync.

This tool is especially useful for:

Cinematographers and videographers dialing in a specific motion-blur look.
Anyone shooting under practical or set lighting who needs to avoid banding on camera.
Productions switching frame rates mid-shoot who need to recalculate the equivalent shutter speed fast.