Monohybrid Cross Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026The classic genetics cross, worked automatically
A monohybrid cross tracks inheritance of a single gene between two parents, predicting the genotype and phenotype ratios expected among their offspring based on simple Mendelian inheritance with complete dominance.
Worked example
For a cross between two heterozygous parents (Aa x Aa):
Result = 3/4 dominant phenotype, 1/4 recessive phenotype
This is the classic 3:1 phenotype ratio that Gregor Mendel himself observed and used to establish the foundational laws of inheritance - it arises because 3 of the 4 possible offspring combinations (AA, Aa, Aa) carry at least one dominant allele, while only 1 combination (aa) is fully recessive.
This model assumes simple complete dominance - real inheritance patterns can be more complex, including incomplete dominance, codominance, and genes influenced by multiple loci, which this simplified single-gene model does not capture.