Quote Originally Posted by Steve Smith View Post
It does work if you use the ratio of the areas of the print rather than the enlarger height squared...
That's how I used to do it. Factor by the change in the size (area) of the paper then make a test strip. Then you have to also consider that your contrast is going to change, too.
I made up a chart for my most-used print sizes: 4x5, 5x7, 8x10, 11x14. Just multiply by the factor from the chart and add or subtract contrast as indicated.

But, it's been months since I did all that. I don't even know where my chart is. I think I tossed it out.
Since I got an Analyser Pro, I don't putz around with that stuff anymore. I just take two readings then push the "Print" button.

Seriously! Pull your Christmas gift card money together and get one!