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LH to FSH ratio calculator

Is my LH to FSH ratio a sign of PCOS?

Q: Does a high ratio mean I have PCOS?

No. PCOS is diagnosed on the Rotterdam criteria — irregular ovulation, clinical or biochemical androgen excess, and polycystic ovarian morphology. The LH:FSH ratio was dropped from those criteria precisely because it is neither sensitive nor specific enough.

Q: When should the blood be taken?

Day 2 to 3 of the cycle for the values to be comparable to reference ranges. A sample taken mid-cycle around the LH surge will produce a very high ratio that means nothing.

Q: Do I need this test at all?

Probably not on its own. Most units diagnosing PCOS work from cycle regularity, ultrasound appearance, and androgen levels. If your clinician has ordered LH and FSH, it is usually as part of a wider baseline panel rather than to calculate this ratio.

A ratio sometimes used when evaluating PCOS patterns. Supportive information only — it neither confirms nor excludes a diagnosis.

IU/L

Day 2–3 of your cycle

FSH

IU/L

Day 2–3 of your cycle

These are example numbers. Replace them with yours, then press Calculate.

Example answer

1.20: 1

1–2

Within the range seen in most people. Not suggestive of anything on its own.

This is a guide, not a diagnosis. Share the result with your doctor.

Your result on the scale

The ranges this calculator uses. Yours is highlighted.

Your numbers

Everything worked out from what you entered.

LH: 6 IU/L
FSH: 5 IU/L

What each result means

Your result is highlighted. Your own clinic's advice always comes first.

Your result<1

LH below FSH. Common and unremarkable in most cycling women.

Your result1–2

Within the range seen in most people. Not suggestive of anything on its own.

Your result2–3

Raised. Seen in some people with PCOS, though many with PCOS have a normal ratio and many without PCOS have a raised one.

Your result3+

Notably raised. Worth interpreting alongside cycle regularity, ultrasound findings and androgen levels rather than alone.

Where this fits in your journey

The usual order, from trying to conceive to pregnancy. Not everyone needs every stage. This calculator belongs to stage 2.

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This calculator: Is my LH to FSH ratio a sign of PCOS?

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How this is worked out

Exact calculationArithmetic on the numbers you enter. If your inputs are right, this figure is right.

The LH to FSH ratio was once used to support a PCOS diagnosis but was dropped from the Rotterdam criteria because it is neither sensitive nor specific enough. A raised ratio is supportive information only, never diagnostic.

About this calculator

?What it tells you

A supporting check only, never a diagnosis. A ratio sometimes used when evaluating PCOS patterns. Supportive information only — it neither confirms nor excludes a diagnosis.

✓When to use it

Only if a clinician has ordered both as part of a PCOS workup

iWhat you need

LH (IU/L)
FSH (IU/L)

!What it cannot tell you

This ratio is supportive information only and is not diagnostic of any condition.

Common questions

Does a high ratio mean I have PCOS?

No. PCOS is diagnosed on the Rotterdam criteria — irregular ovulation, clinical or biochemical androgen excess, and polycystic ovarian morphology. The LH:FSH ratio was dropped from those criteria precisely because it is neither sensitive nor specific enough.

When should the blood be taken?

Day 2 to 3 of the cycle for the values to be comparable to reference ranges. A sample taken mid-cycle around the LH surge will produce a very high ratio that means nothing.

Do I need this test at all?

Probably not on its own. Most units diagnosing PCOS work from cycle regularity, ultrasound appearance, and androgen levels. If your clinician has ordered LH and FSH, it is usually as part of a wider baseline panel rather than to calculate this ratio.

Sources

The LH:FSH ratio is no longer part of the Rotterdam diagnostic criteria for PCOS and is regarded as supportive rather than diagnostic.

In an emergency

If you have any of the warning signs listed here, don't wait for a test result or a calculator. Get help now.

112All emergencies, anywhere in India 108Ambulance

Also call your IVF clinic. Most clinics give an emergency number on your treatment or discharge sheet. Save it in your phone now, before you need it.