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Development calculator

Choose a film and a developer, then the dilution, speed and temperature the time was published for. You get the maker’s time with the datasheet it came from — and, if you need them, corrections for a warmer bath (NegaKit’s rule) or a reused developer (the maker’s own rule, where it publishes one).

Develop for 10:30

  1. Film

    513 films have published times.

    Ilford Delta 3200 Professional · ISO 3200 · B&W

  2. Developer

    Only developers with published times for this film.

    Fomadon Excel W27 1 time Fomadon P 1 time Fomadon R09 1 time Ilford ID-11 12 times Ilford Ilfosol 3 20 times Ilford Ilfotec DD 6 times Ilford Ilfotec DD-X 11 times Ilford Ilfotec HC 13 times Ilford Ilfotec LC29 13 times Ilford Ilfotec RT Rapid 10 times Ilford Microphen 11 times Ilford Perceptol 8 times

  3. Dilution

    The only one published for this choice.

    1+4

  4. Speed

    Only speeds with a published time: a push or pull nobody published is not offered.

    EI 400 pull 3 stops EI 800 pull 2 stops EI 1600 pull 1 stop EI 3200 box speed EI 6400 push 1 stop EI 12500 push 2 stops

  5. Temperature

    The only one published for this choice.

    24 °C

How the numbers are worked out

Only what is published

Every time is a maker’s or a source’s own, read off the datasheet linked beside it. Speeds, dilutions and temperatures are the ones published: nothing is extrapolated, so a push nobody published is simply not on the list.

A warmer or cooler bath

For black-and-white film only, and only between 18 and 26 °C: about 9 % shorter for each degree warmer, rounded to 5 seconds. It is the rule NegaKit’s developing timer uses, which follows Ilford’s and Kodak’s temperature charts closely in that range. Colour processes and monobaths are not corrected.

A reused developer

Only where the maker publishes a rule for a reused developer, and then the maker’s own, with its words and a link to the sheet. A maker that is silent gets no correction: the page says so rather than borrow a percentage. Where the rule is printed for a fixed volume, we scale it to your tank in proportion, and past the maker’s stated capacity we tell you to mix fresh developer.