Recombination Frequency & Genetic Map Distance (cM)

Recombination Frequency & Genetic Map Distance (cM) | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Education
Input types: select, number, text
Output type: json
Sample coverage: 4
API ready: Yes

Overview

The Recombination Frequency & Genetic Map Distance calculator converts testcross counts into recombination frequency and genetic distance in centimorgans (cM), or sums map intervals and predicts the overall recombination frequency. It provides linear, Haldane, and Kosambi estimates, plus the standard error of r in counts mode. Educational use only.

When to use

Calculate recombination frequency from recombinant offspring and total progeny counts.
Compare linear, Haldane, and Kosambi genetic map distances in cM.
Add adjacent map intervals and estimate the recombination frequency across the full span.

How it works

1Choose Counts → recombination & map distance or Map intervals → total distance & predicted r.
2In counts mode, enter the recombinant count and total progeny; the calculator computes r as recombinant count divided by total progeny.
3The result reports linear distance and map-function estimates from Haldane and Kosambi, with the standard error of r.
4In intervals mode, enter comma-separated adjacent distances in cM; the calculator sums them and predicts r using the inverse Haldane and Kosambi functions.

Use cases

Teaching linkage, crossing-over, double crossovers, and genetic map functions in genetics courses.
Checking recombination calculations from testcross or offspring-count exercises.
Building a linkage-map span by summing adjacent cM intervals and comparing predicted recombination frequencies.

Examples

1. Estimate map distance from 18 recombinant offspring

Genetics student

Background

A testcross produces 18 recombinant offspring among 100 total progeny.

Problem

The student wants to compare the observed recombination frequency with map distances from three common mapping approaches.

How to use

Select Counts → recombination & map distance, enter 18 for Recombinant count and 100 for Total progeny, and choose 4 decimal places.

Recombinant count: 18; Total progeny: 100; Decimal places: 4

Outcome

The calculator reports r = 0.18, or 18%. The linear estimate is 18 cM, the Haldane estimate is 22.3144 cM, and the Kosambi estimate is 18.8443 cM.

2. Sum three linkage-map intervals

Genetics instructor

Background

A linkage map contains adjacent intervals of 5.2, 8.1, and 12.0 cM.

Problem

The instructor needs the total map span and the predicted recombination frequency across all three intervals.

How to use

Select Map intervals → total distance & predicted r and enter 5.2, 8.1, 12.0 in the Interval distances in cM field.

FAQ

What is recombination frequency?

Recombination frequency is the number of recombinant offspring divided by the total progeny, expressed as r or a percentage.

What units does the calculator use for genetic distance?

Genetic distance is reported in centimorgans (cM). One Morgan equals 100 cM.

What is the difference between the Haldane and Kosambi estimates?

Haldane assumes no interference, while Kosambi accounts for positive interference. For the same r, Haldane generally gives a larger distance than Kosambi.

Why can map distance exceed 50 cM when recombination frequency cannot?

Multiple crossovers can conceal recombination events, so r approaches 50% while mapping functions can estimate distances greater than 50 cM.

Can this calculator be used for clinical or diagnostic decisions?

No. It is intended for educational use only.

Interval distances in cM: 5.2, 8.1, 12.0; Decimal places: 4

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Estimate map distance from 18 recombinant offspring

2. Sum three linkage-map intervals

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