---
title: "Phenotypic Ratio — AP Bio Definition & Exam Guide"
description: "The phenotypic ratio is the proportion of observable traits among offspring from a genetic cross. Learn the 3:1, 9:3:3:1, and 1:2:1 ratios for AP Bio Unit 5."
canonical: "https://fiveable.me/ap-bio/key-terms/phenotypic-ratio"
type: "key-term"
subject: "AP Biology"
---

# Phenotypic Ratio — AP Bio Definition & Exam Guide

## Definition

The phenotypic ratio represents the relative proportions or percentage distribution of various observable traits among offspring resulting from a genetic cross.

## Review

### Related Terms

- Genotypic Ratio: The relative proportions or percentage distribution of different genotypes among offspring resulting from a genetic cross.
- [Independent Assortment](/ap-bio/key-terms/independent-assortment): The random separation and distribution of alleles for different genes during gamete formation.
- Monohybrid Cross: A genetic cross involving a single trait or gene between two individuals.