Darkroom Wizard Web

New print exposure time

Enter the time that worked for a print at one size, then the new size. The time scales with print area. Then change the f/stop to adjust it.

Inches accept fractions, e.g. 12 1/4.

Current print height Current print width New print height New print width Current print time (mm:ss) f/stop used

New print time

00:00

Change f/stop to

Calculate first, then pick a new f/stop to adjust the time. Exposure scales with the square of the f-number.

From value From To

Converted value

For a ratio such as 1:9, enter 1 and 9 and the final volume you want.

Ratio part 1 (solution) Ratio part 2 (water) Final volume

Part 1 volume

Part 2 volume

The resulting strength when you combine a concentrate with a weaker solution (or plain water, 0%).

Percent of concentrate Volume of concentrate Percent of dilute Volume of dilute

Resulting strength

How much stock solution and water you need to make a given volume at a lower strength.

Percent of stock Final percent wanted Final volume

Stock needed

Water needed