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Speed Change Calculator

Calculate speed percentage when changing between different frame rates

Purpose

The Speed Change Calculator determines the exact speed percentage needed when converting footage between different frame rates. This is essential for format conversions, international distribution, and maintaining proper sync between audio and video.

When to Use

Common Scenarios

  • • Converting 24fps film to 25fps PAL video (4.17% speed increase)
  • • Converting 30fps to 24fps for cinema (20% speed decrease)
  • • Matching footage shot at different frame rates
  • • Planning speed ramping effects
  • • International format conversions

Professional Applications

  • • Film-to-TV transfers
  • • Broadcast standard compliance
  • • Audio pitch correction planning
  • • Multi-camera sync adjustments
  • • Archive material conversion

Step-by-Step Guide

  1. Select Speed Change Calculator

    This calculator loads by default when you open CineMath

  2. Set Source Frame Rate

    Tap the first dropdown and choose your original footage frame rate. Common options include: 23.976, 24, 25, 29.97, 30, 50, 59.94, 60 fps

  3. Set Target Frame Rate

    Tap the second dropdown and choose your desired output frame rate

  4. Read the Result

    The speed percentage appears immediately (e.g., "104.17%" for 24→25fps conversion)

  5. Save if Needed

    Tap the Save button to store this calculation in your history for future reference

Example Calculations

Common Frame Rate Conversions

24fps → 25fps
104.17%
4.17% faster, shorter duration
Used for: Film to PAL video
30fps → 24fps
80.00%
20% slower, longer duration
Used for: Video to cinema
23.976fps → 24fps
100.10%
0.10% faster, minimal change
Used for: Broadcast sync
25fps → 23.976fps
95.90%
4.10% slower
Used for: PAL to NTSC

Understanding Results

Speed Above 100%

  • • Faster playback - content plays quicker
  • • Shorter duration - total runtime decreases
  • • Higher pitch - audio becomes sharper
  • • More motion blur - movement appears smoother

Example: 2-hour film at 104.17% = 1 hour 55 minutes

Speed Below 100%

  • • Slower playback - content plays slower
  • • Longer duration - total runtime increases
  • • Lower pitch - audio becomes deeper
  • • Less motion blur - movement appears choppier

Example: 1-hour video at 80% = 1 hour 15 minutes

Pro Tips

🎯 Accuracy Tips

  • • Use precise frame rates (23.976 vs 24) for professional work
  • • Always verify audio sync after speed changes
  • • Consider using optical flow for better slow-down quality
  • • Small changes (under 5%) are often imperceptible to viewers

🔧 Workflow Tips

  • • Save common conversions to history for quick access
  • • Use for audio pitch correction calculations
  • • Essential for international format conversions
  • • Cross-reference with broadcast timing requirements

⚠️ Important Considerations

  • • Audio pitch will change unless separately corrected
  • • Motion blur characteristics will be affected
  • • Consider audience perception of speed changes
  • • Plan for potential quality degradation with large changes

Troubleshooting

Result shows "Ready for your calculation"

Cause: Both frame rates need to be selected

Solution: Ensure both Source and Target frame rate dropdowns have values selected

Result shows 100.00%

Cause: Source and target frame rates are identical

Solution: Select different frame rates, or this indicates no speed change is needed

Unexpected speed percentage

Cause: Frame rates may be confused (source vs target)

Solution: Double-check which frame rate is your source and which is your target

Related Calculators

Target Length Calculator

Calculate required frame rate to achieve specific duration

Timecode Calculator

Available in CineMath app

← All Calculator GuidesTarget Length Calculator →