Pick the inheritance pattern and each parent's genotype. This page builds the Punnett square and works out the probabilities: affected, carrier, or unaffected. Load a practice problem with one tap.
Set up the cross
A capital letter is the dominant allele. A lowercase letter is the recessive one.
Pattern
Condition
Parent 1
Parent 2
The Punnett square
Reading it: each box is one equally likely child, so each box is 25%. Count the boxes of a type and divide by 4. Red means affected. Amber means carrier, which is one recessive allele but no condition. Green means unaffected.