Shutter Speed Calculator
Find the slowest shutter speed that stays sharp for handholding or for moving subjects.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
The oldest rule in photography is that the safe handheld shutter speed is one over the focal length, and it needs adjusting for crop sensors. Fast-moving subjects need a separate calculation based on how far they travel during the exposure.
Worked example
calculated with the default values below
Focal length 85 mm · Crop factor Full frame · Image stabilisation None · Subject speed 0 km/h · Subject distance 5 m · Acceptable blur 0.03 mm Safe handheld shutter speed 1/85 · Rule of thumb value 0.011765 s · Shutter to freeze the subject No limit · Estimated shutter speed 1/85 · Stops gained from stabilisation 0 stops
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
T_h = 1÷(F×c)÷2^s; T_m = b÷[(v÷3.6)×(F÷1000)÷D]; T = min(T_h, T_m)
- F
- Focal length (mm)
- c
- Crop factor
- s
- Stabilisation stops
- v
- Subject speed (km/h)
- D
- Subject distance (m)
- b
- Acceptable blur threshold
- T_h
- Handheld-safe shutter speed (s)
- T_m
- Motion-freeze shutter speed (s)
- T
- Recommended shutter speed (s)
Recommended speed is the smaller of handheld-safe and motion-freeze values; v÷3.6 converts km/h to m/s; with no moving subject the motion limit is unrestricted; output is shown as 1/n s.
Frequently asked questions
How does the stabilization setting affect the reported handheld shutter?
The model starts with 1 ÷ effective focal length as a rough no-stabilization exposure limit. Each stabilization stop doubles that time, so four stops at 85 mm change about 1/85 s to about 0.19 s, or 1/5.3 s. Subject movement imposes a separate limit; the recommendation uses whichever exposure time is shorter. Actual stabilization performance varies.