So here's the link I was reading when I decided to try my hand at building chicken ladders:
https://www.thefeatherbrain.com/blog/chicken-coop-ramps#ladder
And here's a terrible picture of my attempt at building a ladder with 2x3's for the sides and cut beaver sticks for the rungs (with chicken for scale!

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View attachment 2571136
I move it here and there from time to time to see how they do with different angles but I could provide some actual measurements if you want. They often climb it, or choose to skip rungs. The Lavender Orpington, as the biggest and the one I was worried about the most, naturally prefers to leap off the top.