Motion Blur Shutter Calculator
When photographing a moving subject, the shutter speed must be fast enough to keep blur below an acceptable threshold. The amount of blur in the image depends on how fast the subject moves across the sensor, which is determined by the real-world speed, the distance to the subject, and the focal length of the lens. Longer lenses and closer subjects magnify movement, requiring faster shutter speeds. This calculator finds the maximum shutter speed to limit motion blur to a specified amount in the image plane.
Motion blur formula
Image plane speed (mm/s) = subject speed (m/s) x 1000 x focal length (mm) / subject distance (mm)
Max shutter (s) = acceptable blur (mm) / image plane speed (mm/s)
Subject distance must be in the same units as focal length. Example: 5 m/s subject, 10 m away, 200 mm lens, 0.025 mm blur limit. Image plane speed = 5 x 1000 x 200 / 10,000 = 100 mm/s. Max shutter = 0.025 / 100 = 0.00025 s = 1/4,000 s.
Typical subject speeds for reference
- Person walking: about 1.4 m/s
- Person jogging: about 3 m/s
- Sprinting athlete: about 10 m/s
- Car at 60 km/h: about 16.7 m/s
- Bird in level flight: about 10 to 25 m/s
- Racing car at 200 km/h: about 55.6 m/s
Motion blur calculator: frequently asked questions
How is the motion blur shutter speed calculated?
The maximum shutter speed to limit blur to one pixel or a target blur diameter is: shutter (s) = (acceptable blur in mm) / (subject speed in mm/s at the image plane). The subject speed at the image plane = real speed x (focal length / subject distance). Subject speed in mm/s = real_speed_m_s x 1000 x focal_mm / distance_mm.
What is an acceptable blur amount?
For sharp images, 1 pixel of blur is a common target. For general print use, the circle of confusion (about 0.025-0.030 mm for full frame) is a reasonable limit. For action sports you might allow 2-3 pixels. For creative motion blur you choose a larger value intentionally.
Does focal length affect the required shutter speed?
Yes. A longer focal length magnifies subject movement as well as the subject itself. A subject crossing at 5 m/s appears to move much faster in the frame at 400 mm than at 50 mm. Longer lenses require proportionally faster shutter speeds to freeze the same subject.
What shutter speed freezes a walking person?
A walking adult moves at about 1.4 m/s. At 5 m distance with a 50 mm lens and a 0.025 mm blur limit: shutter = 0.025 / (1400 x 50 / 5000) = 0.025 / 14 = about 1/560 s. A shutter speed of 1/500 s or faster will freeze a walking person at that distance.
How fast does the shutter need to be for birds in flight?
Birds in flight can move at 10-30 m/s. At 10 m/s, 50 m distance, 400 mm lens, 0.025 mm blur limit: shutter = 0.025 / (10000 x 400 / 50000) = 0.025 / 80 = 1/3200 s. Fast birds at closer range need 1/2000 s or faster.
Official sources
- ISO 12232:2019: Photography, Digital still cameras. ISO.org.
- NIST: Optical metrology references. NIST.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.