Home / Calculators / Fertility assessment / LH to FSH ratio
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These tools provide general information and are not a diagnosis or a substitute for assessment by a qualified clinician. Reference ranges and sources are stated on each calculator. Predictive estimates describe groups of people and cannot predict an individual outcome.
A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.
Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.
A ratio sometimes used when evaluating PCOS. Supportive, never diagnostic.
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.
Source — The LH:FSH ratio is no longer part of the Rotterdam diagnostic criteria for PCOS and is regarded as supportive rather than diagnostic.
Day 2–3 of your cycle
Day 2–3 of your cycle
That falls in the 1–2 band.
Your result of 1.20 : 1 sits in the highlighted band. Bands are reference points used alongside clinical findings — not a diagnosis.
Within the range seen in most people. Not suggestive of anything on its own.
The LH:FSH ratio is no longer part of the Rotterdam diagnostic criteria for PCOS and is regarded as supportive rather than diagnostic.
Highlighted is the stage this measurement belongs to. It is a map of the process, not a schedule — timings vary by protocol and by clinic.
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.
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.
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 calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.
Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.
This ratio is supportive information only and is not diagnostic of any condition. Nothing here is a diagnosis or a substitute for assessment by a clinician.
A calculator gives you a number. These explain what it means, and what it does not.
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