Film development is both an art and a science. After years of juggling between scattered resources - dilution calculators, development charts, and various timing tools - I’ve created a comprehensive solution tailored specifically for black and white film development. This calculator combines the essential tools needed for consistent, repeatable results in the darkroom.

The calculator below helps determine precise chemical mixtures and timing, while the reference tables below provide a foundation for understanding different developers and their characteristics. Whether you’re just starting out or are a seasoned darkroom printer, having reliable information and tools in one place can make the development process more consistent and enjoyable.

Keep in mind that I’m a bit of a Gonzo developer. These times and dilutions may not be perfectly accurate and your mileage may vary.

Film Development Calculator

Working Chemical Dilutions & Stock Life

Notes:

• Storage life assumes proper storage conditions: cool, dark place in full, tightly sealed bottles
• Stock solution life assumes unopened or well-preserved (e.g., with glass marbles or inert gas)
• High temperature and oxidation significantly reduce storage life
• All working solutions should be used immediately after mixing
• Always test old solutions with non-critical film first
• Storage life estimates are conservative; actual life may be longer under ideal conditions

Rodinal Development Times for Common Film Stocks (20°C/68°F)

Notes:

• All times assume standard agitation (5 inversions initial, then 2 inversions every minute)
• Stand development (1:100) typically requires 60 minutes with minimal agitation
• Times may need adjustment based on desired contrast and personal workflow
• Temperature should be maintained throughout development

Troubleshooting Common Development Issues

Uneven Development

• Streaks or bands across the film

  • Cause: Insufficient or uneven agitation
  • Solution: Maintain consistent agitation pattern; ensure inversions are complete and gentle

• Edge-to-edge density variations

  • Cause: Temperature variations or insufficient chemical volume
  • Solution: Use at least 250ml per roll of 35mm, 500ml for 120; pre-soak film to normalize temperature

• Blotchy or mottled negatives

  • Cause: Developer exhaustion or uneven agitation during stand development
  • Solution: Use fresh chemicals; ensure minimal vibration during stand development

Density Issues

• Negatives too dense (too dark)

  • Causes:
    • Over-development
    • Temperature too high
    • Film overexposed
  • Solutions:
    • Check thermometer calibration
    • Reduce development time by 10-15%
    • Consider using more dilute developer

• Negatives too thin (too light)

  • Causes:
    • Under-development
    • Developer exhaustion
    • Temperature too low
    • Film underexposed
  • Solutions:
    • Use fresh developer
    • Increase development time by 10-15%
    • Check thermometer calibration

Grain and Sharpness

• Excessive grain

  • Causes:
    • Over-development
    • Temperature too high
    • Excessive agitation
  • Solutions:
    • Use less aggressive agitation
    • Consider more dilute developer
    • Switch to fine-grain developer like Perceptol

• Lack of sharpness

  • Causes:
    • Under-development
    • Insufficient agitation
    • Developer too dilute
  • Solutions:
    • Increase agitation frequency
    • Use more concentrated developer
    • Consider developer known for acutance (like Rodinal)

Chemical Issues

• Developer suddenly stops working

  • Causes:
    • Oxidation
    • Contamination
    • “Sudden death” (especially with XTOL)
  • Solutions:
    • Mix fresh chemicals
    • Use distilled water
    • Test developer with scrap film before critical work

• Color staining

  • Causes:
    • Insufficient fixing
    • Developer oxidation
    • Contaminated stop bath
  • Solutions:
    • Extend fixing time
    • Use fresh chemicals
    • Two-bath fix for important work

Processing Defects

• Physical damage marks

  • Causes:
    • Rough handling
    • Crimped film in reel
    • Scratched emulsion
  • Solutions:
    • Practice loading technique
    • Check reels for damage
    • Handle film only by edges

• Air bells or blank spots

  • Causes:
    • Air trapped during development
    • Insufficient wetting
    • Contamination on film
  • Solutions:
    • Tap tank after initial agitation
    • Use pre-soak with Photo-Flo
    • Clean reels thoroughly between uses

Prevention Tips

• Always mix fresh chemicals for important work
• Keep detailed development logs
• Use thermometer calibration reference
• Maintain consistent agitation patterns
• Pre-soak film when temperature control is critical
• Use enough chemistry (minimum volumes)
• Check equipment regularly for damage
• Practice loading technique with dummy film