Cell division tool Meiosis Calculator

Reduction division tracker

See how chromosome numbers change from meiosis I to meiosis II.

Enter the diploid chromosome number of the starting cell. The calculator shows chromosome count, chromatid count, and cell number after meiosis I and after meiosis II.

Meiosis I halves chromosome number
Meiosis II separates sister chromatids
Final products are haploid cells

Use an even number such as 46 for humans or 8 for a simple classroom example.

Starting cell

46 chromosomes
92 chromatids after DNA replication • 1 cell

After meiosis I

23 chromosomes per cell
46 chromatids per cell • 2 cells

After meiosis II

23 chromosomes per cell
23 chromatids per cell • 4 cells
Quick rule 46 chromosomes (2n) → 23 chromosomes per cell after meiosis I → 23 chromosomes per cell after meiosis II.

Start

Before meiosis

  • The germ cell is diploid (2n).
  • DNA replicates first, so each chromosome has two sister chromatids.
  • Chromosome number stays the same, but chromatid number doubles.
Meiosis I

Reduction division

  • Homologous chromosomes separate into two cells.
  • Chromosome number per cell is cut in half.
  • Each chromosome still has two sister chromatids.
Meiosis II

Equational division

  • Sister chromatids separate.
  • Chromosome number per cell stays haploid.
  • Four haploid cells form, each with one chromatid per chromosome.

Tip: Students often confuse chromosomes and chromatids. After meiosis I, the chromosome number is halved, but each chromosome still has two chromatids. After meiosis II, the chromatids separate, so each chromosome has one chromatid.