Why does film expire?

Photographic film contains light-sensitive silver halide crystals suspended in gelatin layers. Over time, these crystals undergo chemical changes even without exposure to light—a process called "dark decay." In color films, organic dyes that create the final image are particularly vulnerable to degradation, causing color shifts and reduced sensitivity.

The rate of this degradation follows the Arrhenius equation from chemistry: reaction rates approximately double for every 10°C (18°F) increase in temperature. This is why proper storage dramatically extends film life—frozen film can last decades, while film stored in hot conditions may degrade within months.

How does film speed affect shelf life?

Higher ISO/ASA films (like 800 or 1600) use larger silver halide crystals to capture more light. These larger crystals have more surface area, making them more chemically reactive and prone to degradation. Each doubling of ISO reduces shelf life by approximately 10-15%. This is why professional photographers often refrigerate high-speed films immediately after purchase.

Tool description

This calculator estimates how long your photographic film will remain usable based on storage conditions. It uses established photochemistry principles to account for film type, storage temperature, humidity, and film speed (ISO). If you have film with a printed expiration date, the calculator can also determine whether it's still safe to use and recommend an adjusted "use by" date based on your storage method.

Examples

Film Type ISO Storage Humidity Estimated Shelf Life
Color Negative 400 Room Temperature Moderate ~2 years
Color Negative 400 Refrigerated Moderate ~4 years
Color Negative 400 Frozen Low ~8+ years
Black & White 100 Room Temperature Moderate ~5 years
Color Slide 100 Room Temperature Moderate ~2 years
Instant Film 600 Room Temperature Moderate ~1 year

Features

  • Multi-factor calculation: Combines film type, ISO sensitivity, temperature, and humidity into a single shelf life estimate
  • Scientific accuracy: Based on the Arrhenius equation and manufacturer guidelines from Kodak, Fujifilm, and Ilford
  • Expiration date analysis: Enter your film's printed date to see if it's still usable with your storage conditions
  • Quality rating system: Instantly understand storage effectiveness with Excellent/Good/Fair/Poor ratings
  • Extended date calculation: Get a recommended "use by" date that accounts for storage-based preservation

Use cases

  • Bulk film buyers: Photographers who purchase film in quantity can determine optimal storage methods to maximize their investment
  • Found film assessment: Evaluate whether old film discovered in storage is worth developing based on likely storage history
  • Travel planning: Calculate how long film will last in various climate conditions when shooting abroad
  • Archive preservation: Museums and collectors can estimate remaining viable life of historical film stocks
  • Studio inventory management: Professional labs can track film freshness and prioritize stock rotation