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Genetic Linkage Map Distance Calculator

Work out genetic linkage map distance instantly with clear inputs, formula shown and shareable results.

About Genetic Linkage Map Distance Calculator

Converts a recombination frequency into map distance using the Haldane and Kosambi mapping functions, which correct for undetected double crossovers.

Formula

Mapping functions

Haldane: d = -0.5 ln(1 - 2r); Kosambi: d = 0.25 ln((1 + 2r)/(1 - 2r)), both x 100 for centimorgans

Worked example

With the default values below, Genetic Linkage Map Distance Calculator returns Map distance using the chosen function of 15.476. Change any input above and every figure here is recalculated in your browser.

Inputs used

Observed recombination frequencyaccepts 0.01–49.9
15
Preferred mapping functionone of Kosambi (allows for interference), Haldane (no interference)
Kosambi (allows for interference)

Results

Map distance using the chosen function
15.476 cM
Kosambi map distance
15.476 cM
Haldane map distance
17.834 cM
Uncorrected distance
15.000 cM

Step by step

  1. 1Values used
  2. 2Mapping functions
  3. 3Map distance using the chosen function= 15.476 cM
  4. 4Kosambi map distance= 15.476 cM
  5. 5Haldane map distance= 17.834 cM
  6. 6Uncorrected distance= 15.000 cM

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Which function should be used?

Kosambi allows for crossover interference and usually fits real data better than Haldane.

Why does the correction matter?

Uncorrected distances compress at long range, so a genetic map built from raw frequencies is systematically too short.

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