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Punnett Square Generator

Build Punnett squares for five inheritance modes with ratios and export—no account. Built-in AI agent assistant support.

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Key facts

Key facts about Punnett Square Generator
FactValue
Inheritance modesComplete, incomplete, codominant, multiple alleles (ABO), sex-linked (X-linked)
Cross sizeMonohybrid and dihybrid (up to 16 cells)
Presets27 textbook crosses (Classic, Blood Type, Disease, Animal Traits)
OutputsColor-coded grid, genotype/phenotype ratios, proportion bars, step-by-step walkthrough
ExportPNG, SVG, copy table, shareable URL
Runs in browserYes — no install
Account requiredNo
HistorySaved in browser (History tab)

What it does

Hand-drawn Punnett squares invite transcription errors, and basic web tools often apply complete-dominance rules to incomplete or codominant problems—producing wrong phenotype labels for snapdragon flowers, roan cattle, or ABO blood types. The Punnett Square Generator picks the inheritance model first, then builds a live grid with correct phenotype logic for each mode.

Select a dominance mode—Complete, Incomplete, Codominant, Multiple Alleles, or Sex-linked—then enter Parent 1 and Parent 2 genotypes (♀ Parent 1 / ♂ Parent 2 in sex-linked mode). The grid updates as you type, showing genotype and phenotype in each cell, reduced genotype and phenotype ratios, and visual proportion bars. Expand Step-by-step walkthrough to see gamete formation, grid fill, and ratio derivation without working it out by hand.

Load one of 27 curated presets—hemophilia, sickle cell, snapdragon flower color, ABO A × B, roan cattle—or use quick preset chips on the Cross tab. Set optional Custom phenotype labels for dominant, recessive, and heterozygous outcomes. For sex-linked crosses, choose Recessive or Dominant under X-linked trait. Download PNG, Download SVG, Copy table, or Copy URL to share the exact cross; toggle High contrast / print-friendly for worksheets. Recent crosses appear on the History tab in your browser.

Why researchers use it

  • Avoid hand-drawn grid transcription errors
  • Label incomplete and codominant phenotypes correctly
  • Model X-linked crosses with standard notation
  • See gamete-to-ratio logic without separate notes
  • Export print-ready squares for slides and worksheets
  • Share exact crosses with students via link

Best for

  • Introductory genetics homework and exams
  • ABO and MN blood type crosses
  • X-linked recessive and dominant trait problems
  • Incomplete dominance flower and coat color examples
  • Dihybrid Mendelian ratio exercises (9:3:3:1)
  • Building lecture slides, worksheets, and lab handouts

When to use this vs alternatives

Choose this tool when non-Mendelian inheritance, a step-by-step explanation, and exportable grids must live in one browser session. Use the Hardy-Weinberg Equilibrium Studio when you need chi-square or exact tests on observed genotype counts—not offspring ratios from a parental cross. Omni Calculator and punnettsquare.org still fit quick mono- or dihybrid dominant/recessive checks. Bifido Punnett Square Calculator Pro suits linkage, epistasis, and polygenic scenarios but requires Windows and manual trait-file setup.

What makes it different

Most free Punnett tools stop at complete dominance and return a grid without explaining gamete formation—leaving instructors to teach the logic separately. Omni Calculator offers a clean UI but no codominance, ABO, sex-linked, or export. punnettsquare.org handles multi-gene grids and PNG but not non-Mendelian modes or walkthroughs. Bifido Pro covers linkage and epistasis but requires Windows and manual trait-file setup.

This browser generator combines five inheritance modes, 27 curated textbook presets, collapsible gamete-to-ratio walkthroughs, color-coded grids with a print-friendly toggle, and one-click PNG, SVG, table, or share-link export—no install or account. Researchers and instructors switch when students hit incomplete dominance or ABO problems their old calculator cannot handle, or when slide decks need a clean export without redrawing the grid.

How to get started

  1. Open the workspace and stay on the Cross tab.
  2. Select a dominance mode (Complete, Incomplete, Codominant, Multiple Alleles, or Sex-linked).
  3. Enter Parent 1 and Parent 2 genotypes—or click a quick preset chip or Open preset library (or browse the Presets tab).
  4. Optionally set Custom phenotype labels; for sex-linked mode, pick Recessive or Dominant under X-linked trait.
  5. Review the live grid, ratio summary, and expand Step-by-step walkthrough.
  6. Click Download PNG, Download SVG, Copy table, or Copy URL; toggle High contrast / print-friendly for black-and-white printing.

Frequently asked questions

How do I make a Punnett square for incomplete dominance?
Select Incomplete dominance mode, then enter parent genotypes (e.g. Rr × Rr for snapdragon flower color). Heterozygotes receive a blended phenotype label—set Custom phenotype labels for dominant (Red), recessive (White), and heterozygous (Pink). The grid updates live and shows a 1:2:1 phenotype ratio for a monohybrid cross. Expand Step-by-step walkthrough to see how gametes combine and how ratios are counted.
How do I do a Punnett square for ABO blood types?
Choose Multiple Alleles mode and enter genotypes using I^A, I^B, and i alleles (e.g. I^A i × I^B i). The tool applies ABO dominance rules—I^A and I^B are codominant; i is recessive—and labels each cell with blood type phenotype. Load the ABO blood type A × B preset from the library for a textbook example. This mode supports ABO alleles only; other multi-allele systems are not available.
How do I set up an X-linked Punnett square?
Select Sex-linked mode. Enter the female parent as ♀ Parent 1 (e.g. X^H X^h) and the male as ♂ Parent 2 (e.g. X^H Y). Use X^allele notation with Y on the male genotype. Choose Recessive or Dominant under X-linked trait to control carrier-female labeling. The grid flags hemizygous male outcomes and shows reduced phenotype ratios. Try the Hemophilia A (carrier × unaffected male) preset to load a standard problem.
What is the phenotype ratio for a dihybrid cross?
For a dihybrid cross between two double heterozygotes with complete dominance (e.g. AaBb × AaBb), the classic phenotype ratio is 9:3:3:1. Select Complete mode, enter both parent genotypes with two loci each, and read the reduced ratio under phenotype summary. The tool supports up to dihybrid crosses (16 cells); trihybrid and larger grids are not supported.
Can this Punnett square calculator handle more than two genes?
No. The generator supports monohybrid (4 cells) and dihybrid (16 cells) crosses. Entering more than two loci per parent triggers a validation message: maximum dihybrid cross supported. For pentahybrid or multi-gene grids without non-Mendelian modes, punnettsquare.org may still fit; for linkage or epistasis, desktop tools like Bifido Pro are the alternative.
How do I export a Punnett square for a worksheet or slide deck?
After the grid generates, use Download PNG or Download SVG for an image you can paste into Google Docs, PowerPoint, or a lab handout. Copy table pastes a tab-separated grid into a spreadsheet or document. Toggle High contrast / print-friendly to remove background colors for black-and-white printing. Copy URL encodes the cross in the link so students open the same configuration.

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