What color do purple and white make?
Purple and White make pink.

Purple and White make pink, #dfbfdf. That is the result in equal parts, mixing pigment rather than light - paint, ink and dye all behave this way.
Equal parts purple and white · #dfbfdf
Change the ratio
Very little of a mix is ever half and half. Shifting the balance moves the result along the range between the two colours.
3 parts purple, 1 part white · #b060b0
Equal parts · #dfbfdf
1 part purple, 3 parts white · #ecd9ec
Lighter and darker
With white added - a tint · #ecd9ec
With black added - a shade · #734d73
Why it works
Adding white to purple makes a tint. The hue does not change - only its lightness does, which is why you get pink rather than a different colour altogether. Keep adding white and it keeps moving towards plain white.
Frequently asked questions
What color do purple and white make?
Purple and White make pink, #dfbfdf. Mixed in equal parts that is the result you get with paint, ink or any other pigment.
How do I make the result lighter or darker?
Add white for a tint - here that gives beige. Add black for a shade, which gives grey. Add white a little at a time, because it takes far less than people expect to shift a mix.
What happens if I use more purple than white?
Three parts purple to one part white gives lavender. Reversing it to one part purple and three parts white gives beige instead.
Does this work the same way on a screen?
No. Screens mix light additively, so red and green light make yellow there. These results are subtractive - paint, ink, dye and pigment - which is what people mean when they ask what two colours make.