A film development time calculator removes the guesswork from darkroom processing. Development times vary significantly by film stock, developer, dilution, temperature, and whether you are pushing or pulling. Enter your combination below to get an accurate starting time, agitation schedule, and temperature-corrected guidance.
Film & Developer Setup
Standard is 68°F / 20°C
Results
How to Use the Film Development Time Calculator
Getting your film development time right is one of the most critical steps in analog photography. Too little time and your negatives will be thin and lacking shadow detail. Too much time and they will be dense, contrasty, and difficult to print. This calculator takes the guesswork out of the process by combining film stock, developer type, push/pull amount, and temperature into a single accurate result.
Step 1: Select Your Film Stock
Choose your film from the dropdown. The calculator includes 16 of the most popular black-and-white film stocks including Kodak Tri-X 400, Ilford HP5 Plus, Kodak T-Max 400, Fuji Acros 100, Delta 100, FP4 Plus, Fomapan, and Kentmere. Each has different grain structure, tonal characteristics, and development requirements that affect the base time.
Step 2: Choose Your Developer and Dilution
The developer dramatically changes development time and film character. Dilute developers like Rodinal at 1+50 give fine grain and sharp edges but take longer. Concentrated developers like D-76 stock work faster and suit push processing better. The calculator includes 13 developer/dilution combinations: D-76, HC-110, Rodinal, XTOL, ID-11, Microphen, Ilfosol 3, and Perceptol. Select the dilution that matches what you mixed.
Step 3: Set Push or Pull Amount
If you shot your film at a different EI (exposure index) than its box speed, select the corresponding push or pull amount. Pushing 1 stop means you shot ISO 400 film at ISO 800. The development time is extended to compensate for the underexposure. Pulling 1 stop means you overexposed, and the time is shortened to hold back density. You can push up to 3 stops or pull up to 2 stops.
Step 4: Enter Your Developer Temperature
Temperature affects how fast the chemistry reacts. Most published film development times are calibrated for 20°C (68°F). If you are working at a different temperature, the calculator applies a correction factor. A rule of thumb is that every 1°C above 20°C cuts time by about 10%. The calculator supports both Fahrenheit and Celsius input — just toggle the unit selector.
Reading the Results
The results panel shows your development time prominently, plus the recommended agitation schedule, stop bath duration, and fixer time. Follow the agitation schedule exactly — consistent agitation is as important as the right time. The stop bath time assumes a diluted acid stop (Indicator Stop Bath); if using a plain water stop, extend it to 60 seconds. Fix times assume Ilford Rapid Fixer at 1+4 or equivalent.
FAQ
Is this film development time calculator free?
Yes, this film development time calculator is completely free with no signup or account needed. All calculations run locally in your browser — your settings are never sent to any server.
Is my data private?
Absolutely. Everything runs in your browser using JavaScript. No film stock or developer data leaves your device. No cookies, no tracking, no server-side storage.
What does push processing mean in film development?
Push processing means developing film for longer than normal to compensate for underexposure. If you shoot ISO 400 film at ISO 800, you are pushing one stop. The development time is extended to bring out shadow detail. This also increases contrast and grain.
What is pull processing and when should I use it?
Pull processing means reducing development time to compensate for overexposure. If you shoot ISO 400 film at ISO 200, you are pulling one stop. The development time is shortened to reduce contrast and lower grain. It is useful in very bright conditions or when you want a flatter, lower-contrast negative.
How does temperature affect film development time?
Chemical activity increases with temperature. A general rule is that every 10°C increase roughly doubles the reaction speed. Most development charts are calibrated for 20°C (68°F). At 24°C you need significantly less time. This calculator automatically adjusts the development time based on your working temperature.
What is the agitation schedule for film development?
Standard agitation for most sheet and roll film is continuous gentle agitation for the first 30 seconds, then 4–5 inversions every 60 seconds. Stand development uses no agitation after the initial period. The schedule shown here follows the widely-used Ilford and Kodak recommendations for each developer type.
How long should I use stop bath and fixer?
Stop bath halts development immediately and typically takes 30–60 seconds. Rapid fixer for films typically needs 2–5 minutes; conventional fixer takes 5–10 minutes. Always verify with the fixer manufacturer and do a clip test if in doubt. The times shown in this calculator are standard starting points.
Can I mix different film stocks with the same developer?
Yes, but each film and developer combination has its own development time. Always look up the specific combination. This calculator provides data for the most popular pairings. For less common combinations, refer to the Massive Dev Chart or the manufacturer's data sheets.