Biology
Biology Calculators
DNA composition, genetic crosses, allele frequencies, and molecular weight.
7 tools
Blood Type Inheritance Calculator
Blood type inheritance calculator: predict possible child blood types from parent ABO and Rh factor groups in seconds. Free, private, runs locally, no signup.
Chargaff Rule Calculator
Chargaff rule calculator: verify A=T and G=C base pairing rules from DNA composition and find missing base percentages. Free, private, runs locally offline.
DNA GC Content Calculator
DNA GC content calculator: instantly compute the GC percentage of any DNA or RNA sequence from its base composition, in your browser. Free, private, no signup.
Doubling Time Calculator
Doubling time calculator: find how long an investment or population takes to double from any compounding growth rate. Free, editable rates, runs locally.
Hardy Weinberg Calculator
Hardy Weinberg calculator: compute allele and genotype frequencies p, q, p2, 2pq, and q2 from dominant phenotype counts. Free, runs in your browser offline.
Protein Molecular Weight Calculator
Protein molecular weight calculator: estimate a protein's approximate mass in kilodaltons from amino acid chain length. Free, runs in your browser, no signup.
Punnett Square Calculator
Punnett square calculator: build genetic crosses for 1 to 5 gene traits and see genotype and phenotype ratios instantly. Free, runs locally, no signup.
How these biology tools work
Each tool applies its textbook definition directly: GC content is the percentage of bases that are G or C, Punnett squares enumerate gamete combinations, allele frequencies follow the Hardy-Weinberg proportions, and molecular weights sum standard atomic masses. The formulas are shown on every page so the arithmetic is checkable, not hidden.
These are deterministic calculations, not models: given exact inputs the outputs are exact. Where a real lab result would differ, the difference comes from measurement error in your inputs, which the assumptions panel on each tool flags.
Choosing a tool
Match the tool to the question: sequence composition questions use GC content, inheritance questions use the Punnett square, population genetics questions use allele frequency, and primer or protein questions use molecular weight. If your question spans two tools, run both and compare: they share definitions, so a disagreement means an input is wrong.
Honest limits
None of these tools replaces bench verification. They are teaching and planning aids: the Punnett square gives probabilities for single-gene traits, not diagnoses, and molecular weights assume standard isotopic averages.