Development time

Ilford FP4 Plus in Rodinal

6:00 at 20°C, 1+25 dilution, box speed.

Start timer · 6:00

Time

6:00

Standard

Dilution

1+25

Temperature

20°C

Box speed

ISO 125

B&W

All 2 times

Dilution	EI	Time	Temp	Agitation	Timer
1+25	125	6:00Not yet verified	20°C / 68°F	Standard	Start timer
1+50	125	11:00Not yet verified	20°C / 68°F	Standard	Start timer

EI is the speed the film was rated at when shooting. Times marked “not yet verified” come from secondary sources and haven’t been checked against a manufacturer datasheet.

Other temperatures

18°C	19°C	20°C	21°C	22°C	23°C	24°C
7:30	6:43	6:00	5:24	4:48	4:19	3:54

Calculated from the 20°C time using Ilford’s temperature compensation factors, not taken from a datasheet. Most B&W developers behave well between 18°C and 24°C.

Mixing

Dilution	300 ml (one 35mm roll)	500 ml (one 120 roll)
1+25	12 ml developer + 288 ml water	19 ml developer + 481 ml water
1+50	5.9 ml developer + 294 ml water	9.8 ml developer + 490 ml water

How they work together

Rodinal: Prominent grain, high acutance, full film speed, variable contrast. Sharp, dramatic, distinct edge effects.
Ilford FP4 Plus: Often considered a benchmark for medium speed B&W. Notable sharpness and fine grain. Well-suited for high-quality enlargements.
Notes on this pairing: Per historical Rodinal bottle information.
Outstanding tonal qualities in 120 format.

FP4 Plus in other developers

ID-11