Film Fixer Quantity by Rolls

Film Fixer Quantity Calculator

Photographic fixer (sodium thiosulfate or ammonium thiosulfate) clears the undeveloped silver halides out of the emulsion, which is what makes the image stable and safe to bring out into daylight. The basic dose is total_ml = rolls × ml_per_roll; in a small tank you'll typically use 250–300 ml per 35mm roll. Fixing takes 2–5 min for paper and 6–10 min for film, give or take depending on the emulsion and how concentrated your fixer is.

Check for exhaustion with the "clip test." Drop a piece of unexposed film leader into the fixer. Fresh chemistry clears it in under 30 seconds; spent fixer takes twice that or more. Whatever the clearing time, double it and you've got your minimum fixing time. Push exhausted fixer too far and it leaves milky undeveloped silver in the emulsion, which quietly fogs the negative over the following months.

Applications

If you're mixing Ilford Rapid Fixer (1:4 for film, 1:9 for paper), Kodak Kodafix, or Adox Adofix Plus, this estimate tells you how much working solution to make up before a session. A 5L jug of concentrate gives you roughly 25L at working strength, good for about 80 rolls. Neutral-pH fixers are gentler on the emulsion; acid fixers stretch the life of your stop bath but can soften the gelatin.

FAQ

What happens if I underfix? Leftover silver halide darkens over the next weeks and months and fogs the negative for good. Fix for at least twice the clip-test clearing time and you're safe.

Can fixer be reused? Yes. Rapid fixer is good for about 20 rolls per liter of working solution before it gives out. Keep a tally and run a clip test before each session.

How do I dispose of used fixer? Spent fixer carries dissolved silver, so don't pour it down the drain in any quantity. Plenty of photo labs will take it for silver recovery; otherwise check your local hazardous-waste rules.