Film developer dilution calculator: HC-110, Rodinal, ID-11
Enter the dilution from your data sheet (1+31 for HC-110 B, 1+50 for Rodinal) and how much working solution your tank needs. You get the concentrate and the water in mL. If your developer has a minimum amount of concentrate per roll, enter it and the calculator checks the mix against it. Ilford's Ilfosol 3 (1+9, or 1+14 for more economy) is one of the quick picks, and its development times for HP5 Plus, FP4 Plus and other films are on the Ilfosol 3 development times page. For Kodak D-76 at 1:1, see the D-76 development times.
HC-110 dilution B from concentrate (Kodak J-24)
Kodak's HC-110 data sheet (J-24) lists dilution B as 1:31 from concentrate. Its mixing table gives 9 mL of concentrate for 300 mL, 16 mL for 500 mL, and 31 mL of concentrate plus 969 mL of water for 1 L. From a stock solution (1 part concentrate, 3 parts water) the same dilution B is 1:7. The calculator below rounds to 0.1 mL, so 500 mL shows 15.6 mL where Kodak prints 16.
1+31 or 1:31
The data sheets I checked mean the same thing by both: one part concentrate plus N parts water. Kodak's HC-110 data sheet (J-24, December 2017) writes dilution B as 1:31 and makes 1 liter of it from 31 mL of concentrate and 969 mL of water, so its 1:31 is 1+31. That is one source, so check your own sheet. Ilford writes 1+1 and 1+3, and Adox writes Rodinal dilutions as 1+25 to 1+200.
Ilford's Ilfosol 3 technical information gives 1+9 as the normal one-shot dilution and 1+14 for more economy with a small loss in image quality. Its tank table lists 30 mL concentrate and 270 mL water for 300 mL at 1+9, and 20 mL and 280 mL at 1+14. It also advises against measuring less than 10 mL of concentrate, which is hard to do accurately with a measuring cylinder.
Some recipes may use 1:N for one part in N parts total. For HC-110 B in a 500 mL tank the two readings give 15.6 mL and 16.1 mL of concentrate, close enough at high dilutions. At 1:1 they differ completely (half concentrate, or straight concentrate), so check which one your recipe means.
HC-110 dilution letters
Kodak's J-24 gives each HC-110 dilution a letter, with one ratio from the concentrate and another from a stock solution (1 part concentrate plus 3 parts water). Dilution B is 1:31 from concentrate and 1:7 from stock. From concentrate, J-24 lists A as 1:15, B as 1:31, C as 1:19, D as 1:39, E as 1:47 and F as 1:79. Kodak suggests making the stock solution first because the concentrate is thick, and J-24 also has tables for mixing straight from concentrate.
You may also see "dilution H" for 1+63. It is not in J-24, which stops at F, so it is an informal name and not a Kodak letter. The calculator treats it like any other ratio: enter 63 as N.
Minimum concentrate per roll
A very dilute developer can run out of developing agent before the film is done. Adox states a floor for Adonal (Rodinal): when using high dilutions in small tanks, use at least 5 mL of concentrate for each 35mm or 120 film, and 5 mL for every four 4x5 sheets or one 8x10 sheet (Adox Adonal product page at Fotoimpex).
That rules out Rodinal 1+100 in a 300 mL tank: it holds 3.0 mL of concentrate, and 1+100 needs 505 mL of solution to reach 5 mL. Two 35mm rolls in 500 mL at 1+100 get 5.0 mL against the 10 mL they need. More solution or a stronger dilution fixes it. Kodak's HC-110 sheet and Ilford's powder developer sheet state no such per-roll floor, so the field defaults to 0.
Adox's own example for 1+25 is 12 mL of Rodinal in 288 mL of water for 300 mL (Adox Rodinal page). The exact figure is 11.5 mL; at this strength half a mL either way makes little difference.
Rodinal at 1+100 for stand development
Adox calls very high dilutions "Standentwicklung" (stand development) and lists Rodinal from 1+25 up to 1+200 (Adox Rodinal page, in German). The tank is filled once and left standing with little or no agitation, so the weak developer works slowly. The page says only that higher dilutions take longer and gives no times, so use the time on your film's data sheet. Its intro mentions an agitation pattern of 10 seconds of inversion and 50 seconds standing, without saying which dilution it is for.
The 5 mL per roll floor from the section above sets the tank size. At 1+100, 5 mL of Rodinal needs 505 mL of solution, so the tank volume decides how many rolls fit:
| Tank | Rodinal + water | Against 5 mL per roll |
|---|---|---|
| 300 mL | 3.0 + 297.0 mL | ⚠ Warning: under the minimum for one roll |
| 500 mL | 5.0 + 495.0 mL | ⚠ Warning: under the minimum for one roll |
| 600 mL | 5.9 + 594.1 mL | Enough for 1 roll |
| 1000 mL | 9.9 + 990.1 mL | Enough for 1 roll |
I found no manufacturer times for stand development, so this page gives none. Open the calculator with Rodinal 1+100 and 5 mL per roll, then change the tank volume.
Concentrate for common dilutions
| Developer, dilution | 300 mL | 500 mL |
|---|---|---|
| HC-110 dilution B | 9.4 + 290.6 | 15.6 + 484.4 |
| HC-110 dilution E | 6.3 + 293.8 | 10.4 + 489.6 |
| Rodinal 1+25 | 11.5 + 288.5 | 19.2 + 480.8 |
| Rodinal 1+50 | 5.9 + 294.1 | 9.8 + 490.2 |
| Rodinal 1+100 | 3.0 + 297.0 | 5.0 + 495.0 |
| ID-11 1+1 | 150.0 + 150.0 | 250.0 + 250.0 |
| ID-11 1+3 | 75.0 + 225.0 | 125.0 + 375.0 |
mL of concentrate + mL of water.
How much solution a tank needs
The volume is usually printed on the bottom of the tank. A retailer listing for the Paterson Universal tank says 300 mL of solution is needed for a single 35mm film and 500 mL "for two 35mm and one 120 roll film", which I read as two 35mm films or one 120 film (Focus Nordic). Adox counts 250 mL per film for a Jobo tank in its Rodinal capacity figures, notes that some tanks want 300 mL per film, and says roll film needs 600 mL per film, but two films fit on one spiral and Rodinal manages two films in 600 mL (Adox, in German). Ilford's powder developer fact sheet counts 250–300 mL for one film.
Your time at a given dilution comes from the film's data sheet. If your developer is warmer or cooler than the sheet's 20 °C, the time and temperature calculator adjusts it. For a developer you pour back into the bottle, the reuse calculator adds time for each roll, and the Cs41 page shows it for a C-41 kit.