Mutation Rate Calculator

Calculate mutation rate per base pair per generation from observed new mutations or experimental data. Estimate genome-wide mutation rate and expected mutations per offspring.

🧬 Genetics📐 mu = new mutations / (2N × genome size)🧬 Biology
Number of new mutations observed
Number of parent-offspring trios
Genome size (bp, optional)
Please enter valid values.

Formula & Reference

VariableSymbolFormulaUnits
Mutation Rate Calculator—mu = new mutations / (2N × genome size)per bp per generation

Step-by-Step Examples

Example 1
Human Germline Mutation Rate

60 new mutations observed across 100 parent-offspring trios.

  • Average = 60/100 = 0.6 new mutations per trio? Actually 60 total across 100 trios = 0.6/trio... actually means 60 total observed
  • Per offspring = 60/100 = 0.6 per trio
  • Human rate ~ 1-2 x 10^-8 per bp per gen
  • 60 new mutations / offspring is typical for humans
✓ ~60 new de novo mutations per human child
Example 2
E. coli Mutation Rate

Luria-Delbruck fluctuation test. 5 new mutations in 1000 cell divisions. Genome = 4.6x10^6 bp.

  • Rate = 5/(1000 x 2 x 4.6x10^6)
  • = 5/9.2x10^9 = 5.43x10^-10 per bp per gen
  • E. coli actual: ~5x10^-10 per bp per generation
✓ mu(E. coli) ~ 5x10^-10 per bp/gen
Example 3
From Known Rates

Human rate = 1.2x10^-8 per bp per gen. Genome = 3x10^9 bp. Expected new mutations?

  • Expected = 1.2x10^-8 x 3x10^9 x 2 (diploid)
  • = 72 new mutations per offspring
  • Matches observed ~60-90 from sequencing studies
✓ ~72 expected new mutations per human child

Real-World Applications

🧬
Evolutionary Biology
Mutation rate sets the clock of neutral evolution. Calibrate molecular clocks for dating divergence times.
💊
Cancer Genetics
Somatic mutation rates elevated in cancer cells. Mutational signature analysis reveals carcinogen exposure.
🧬
Disease Genetics
De novo mutations cause ~15-30% of severe intellectual disability and autism spectrum disorders.
🌍
Conservation
High mutation rate in small populations can accelerate evolution or accumulate deleterious alleles.

Common Mistakes to Avoid

⚠️
Distinguish germline from somatic mutations

Germline mutations are heritable (passed to offspring). Somatic mutations affect only the individual. Germline rate: ~1-2x10^-8/bp/gen in humans.

⚠️
Mutations per base pair, not per genome

Rate per bp is comparable across organisms with different genome sizes. Per-genome rate = rate per bp x genome size.

⚠️
Paternal age effect

In humans, mutation rate increases with paternal age (~2 additional de novo mutations per year of paternal age). Most new mutations from fathers.

Frequently Asked Questions

What is the human mutation rate? ▾
~1.1-1.2 x 10^-8 mutations per base pair per generation. About 60-80 new mutations per child. About 2/3 from the father (sperm cell divisions much more frequent than egg divisions).
What is the mutation rate of viruses? ▾
RNA viruses: ~10^-4 to 10^-6 per base per replication (no proofreading). DNA viruses: ~10^-7 to 10^-9. This high rate is why RNA viruses (flu, HIV) evolve rapidly.
What is the molecular clock? ▾
Neutral mutations accumulate at a rate proportional to the mutation rate. This allows dating of evolutionary divergences. Calibrated using known fossil dates.
What factors increase mutation rate? ▾
Mutagens (UV, X-rays, chemicals). High temperature. Replication errors. Paternal age. Defects in DNA repair genes (BRCA, MMR genes). Transposable element activity.
Why do de novo mutations cause disease? ▾
New mutations in developmental genes can disrupt critical functions. Most severe genetic diseases (achondroplasia, new autism cases) arise from de novo mutations, not inherited variants.

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