Sperm Analysis Calculator (semen results vs WHO 2021 reference limits)

Understanding the semen analysis calculator — concept and principle

This calculator compares semen analysis results with the lower reference limits of the WHO laboratory manual (6th edition, 2021) and works out the total sperm number and total motile sperm count. It helps men and couples understand a fertility test report.

How it is calculated

Total sperm number (million) = volume (mL) × concentration (million/mL)

Total motile sperm (million) = total number × total motility ÷ 100

WHO 2021 lower reference limits: volume 1.4 mL, concentration 16 million/mL, total number 39 million, total motility 42%, progressive motility 30%, vitality 54%, normal forms 4%.

The calculator counts how many values fall below these limits.

The principle

The WHO limits are the 5th centile of men whose partners became pregnant within 12 months. That means 95% of these fertile men had higher values. The limits therefore mark unusually low results compared with fertile men, not a dividing line between fertile and infertile. Total and motile counts combine several measurements into the number of sperm that can actually swim towards an egg.

Worked example

Default inputs: volume 2.8 mL, concentration 35 million/mL, total motility 55%, progressive 38%, normal forms 5%, vitality 70%.

1. Total number = 2.8 × 35 = 98 million.
2. Total motile = 98 × 0.55 = 53.9 million.
3. Each value is at or above its limit (2.8 ≥ 1.4, 35 ≥ 16, 98 ≥ 39, 55 ≥ 42, 38 ≥ 30, 5 ≥ 4, 70 ≥ 54).
4. Values below the WHO lower limits = 0.

How to read the result

Results above all limits are reassuring but do not guarantee fertility; results below a limit do not mean a man cannot father children. Semen quality varies a lot between samples, so an abnormal result is usually repeated after a few weeks. Interpretation belongs with a urologist or fertility specialist, together with the partner's assessment.

Common mistakes

• Not following the 2–7 days of abstinence before the test.
• Losing part of the sample, which lowers volume and total count.
• Comparing with older WHO editions, whose limits differ.

Frequently asked questions

What is a normal sperm count?

The WHO lower limit is 16 million per mL or 39 million per ejaculate.

Why is normal morphology only 4%?

Strict criteria classify most sperm as abnormal even in fertile men.

Can lifestyle affect results?

Smoking, heavy drinking, heat, obesity and some medicines can lower semen quality.

Sources: World Health Organization, WHO laboratory manual for the examination and processing of human semen, 6th ed., 2021