Yellow and purple: What Color Do They Make?

Dark brown

Yellow + purple = dark brown. With more yellow you get khaki; with more purple, plum.

More shades from the same colors

Khaki2 parts yellow + 1 part purplePlum1 part yellow + 2 parts purpleLight browndark brown + white

Yellow + purple: these are opposite colors, so mixed together they cancel each other out and make dark brown. A tiny bit of one is enough to tone down the other.
If it gets too dark, add white little by little.

What color do yellow and purple make?

Yellow + purple, in equal parts, make dark brown. With more yellow it leans toward khaki, and with more purple, toward plum.

What ratio of yellow and purple should I use?

Half and half makes dark brown. 2 parts yellow to 1 part purple gives khaki; 1 part yellow to 2 parts purple gives plum.

How do I make dark brown lighter or darker?

Add white little by little to lighten it (light brown) or a little black to darken it (dark brown).

Why do yellow and purple make dark brown?

Because they are complementary colors: they sit opposite each other on the color wheel, so when mixed they cancel each other out.