--- title: "The LH to FSH Ratio: What It Signals in PCOS, Perimenopause and Fertility Testing, When to Draw It, and How to Calculate It" type: guide url: "https://www.test-well.com/guides/lh-fsh-ratio" date_published: 2026-10-09 reviewed_at: 2026-10-09 --- # The LH to FSH Ratio: What It Signals in PCOS, Perimenopause and Fertility Testing, When to Draw It, and How to Calculate It *Divide LH by FSH from a cycle day 2–4 draw and you get a number that shows up in every PCOS forum and almost no diagnostic criterion. Here is what the ratio actually signals, why the cycle day decides whether it means anything, what to read instead when FSH is high, and a calculator that does the arithmetic.* > The LH:FSH ratio is luteinizing hormone divided by follicle-stimulating hormone, both from the same blood draw on cycle day 2–4. In that early-follicular window FSH normally sits at or a little above LH, so a ratio of about 1 or below is the usual pattern. A ratio of 2 or more — LH well above FSH — is seen in many women with polycystic ovary syndrome, but it is not a diagnostic criterion: Rotterdam and the 2023 international guideline diagnose PCOS from irregular ovulation, clinical or biochemical androgen excess, and ovarian morphology or AMH. When FSH is high, the ratio drops below 1 and the information is in the FSH value itself, read with estradiol and AMH as a reserve or perimenopause signal. Timing comes before interpretation: LH rises several-fold around ovulation, so a mid-cycle sample flips the ratio in a woman with normal hormones, and hormonal contraception, pregnancy and breastfeeding change both values. In men the ratio is not used; LH and FSH are read individually against total testosterone. ## Recommended tests | Recommended | Type | Price | Why | | --- | --- | --- | --- | | [LH (Luteinizing Hormone)](https://www.test-well.com/tests/luteinizing-hormone) | Test | $36.99 | Luteinizing hormone — $36.99, results in 1–3 business days | | [FSH (Follicle Stimulating Hormone)](https://www.test-well.com/tests/fsh) | Test | $29.99 | Follicle-stimulating hormone — $29.99, drawn with LH on cycle day 2–4 | | [Women's Fertility Essentials](https://www.test-well.com/tests/female-fertility-panel) | Panel (5 tests) | $119.99 | AMH, FSH, LH, estradiol and progesterone in one draw — $119.99 | | [Women's Hormone Panel](https://www.test-well.com/tests/womens-hormone-panel) | Panel (11 tests) | $239.99 | FSH and LH with estradiol, testosterone, SHBG, DHEA-S and prolactin for the full PCOS picture | All prices are cash-pay plus one $6 lab processing fee per order; physician authorization is included. ## The One-Paragraph Answer Luteinizing hormone and follicle-stimulating hormone are released together by the pituitary, and the **LH:FSH ratio** is simply one divided by the other from a single blood draw. It only means something when the draw happens at baseline — **cycle day 2–4** in a woman who is cycling and not on hormonal contraception — because that is the one window in which both hormones are quiet and comparable. There, FSH is normally at or slightly above LH, so the usual ratio is about 1 or below. The pattern people search for is the reverse: LH two or three times FSH, which is **common in polycystic ovary syndrome** and was once treated almost as a test for it. It is not. The [PCOS](https://www.test-well.com/conditions/pcos) criteria in use today — Rotterdam and the 2023 international guideline — rest on ovulatory dysfunction, androgen excess, and ovarian morphology or AMH; the ratio is supporting evidence a clinician may note, not a line a result has to cross. And when the ratio falls well below 1 because FSH is high, the useful information is the FSH number itself, which is how ovarian reserve and the menopausal transition are read. ## Why the Cycle Day Comes Before the Number Every LH:FSH interpretation assumes an **early-follicular sample**. LH rises several-fold for roughly a day around ovulation — the surge that ovulation predictor kits detect — so a sample drawn mid-cycle will show LH far above FSH in a woman whose hormones are entirely normal. Later in the cycle both hormones fall as progesterone rises. The [FSH vs LH guide](https://www.test-well.com/guides/fsh-vs-lh) covers what each hormone does across the cycle; for the ratio, the practical rule is: **day 2, 3 or 4 counting the first day of full flow as day 1, LH and FSH from the same tube**. Three situations make the ratio uninterpretable regardless of day: **hormonal contraception** (the pill, patch, ring, hormonal IUD in some women) suppresses both hormones; **pregnancy and breastfeeding** change them; and **irregular or absent cycles** — the very situation in which PCOS is suspected — mean there may be no day 2–4 to aim for. In that last case clinicians draw on any day and interpret the pair alongside estradiol, progesterone and androgens rather than leaning on the ratio. ## What the Common Ratios Usually Mean Day 2–4 sample, cycling woman, no hormonal contraception. The [LH:FSH ratio calculator](https://www.test-well.com/tools/lh-fsh-ratio-calculator) returns the band for your numbers. | LH:FSH | Pattern | What it usually reflects | Read next | | --- | --- | --- | --- | | Below 1 | FSH higher than LH | The expected early-follicular relationship. If FSH is high in absolute terms, the ratio is low because of the FSH, and that is a reserve or perimenopause signal. | The FSH value itself, estradiol, AMH | | About 1 to 2 | Roughly balanced | Common in healthy samples; the ratio adds nothing on its own. | Absolute values, cycle history | | 2 to 3 | LH-predominant | Seen in a large share of women with PCOS; also what a sample drawn near ovulation looks like. Supportive of PCOS, never diagnostic. | Cycle day; testosterone, SHBG, AMH; the clinical criteria | | 3 or more | Strongly LH-predominant | The classic PCOS pattern when timing is right — and the LH surge when it is not. | Confirm the day first, then the same work-up | Two cautions. Published studies disagree on where "elevated" starts — some use 2, some 2.5 or 3 — and a sizeable fraction of women with PCOS have a normal ratio, which is one reason it was never adopted as a criterion. And the absolute values matter as much as the ratio: a ratio of 2 built from an LH of 4 and an FSH of 2 is not the same finding as one built from an LH of 18 and an FSH of 9. ## The PCOS Pattern, and Why the Ratio Is Not a Criterion In PCOS the pituitary tends to release LH in faster, larger pulses while FSH stays relatively low, which is why LH often outruns FSH on a baseline draw. That LH excess also drives the ovarian theca cells to make more androgens, which connects the ratio to the acne, hair growth and ovulation problems that define the condition. It is a real physiological signal — just not a reliable one: a meaningful share of women with PCOS have a normal ratio, particularly at higher body weights, and the ratio is easily inflated by mistimed sampling. That is why the diagnostic criteria leave it out. The **Rotterdam criteria** (2003) require two of three: irregular or absent ovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound, after excluding other causes. The **2023 international evidence-based guideline** keeps that structure and allows an elevated AMH in place of ultrasound in adults; it does not include the LH:FSH ratio. If your ratio is high, the questions that actually settle the diagnosis are about your cycles, your androgen levels (total and free [testosterone](https://www.test-well.com/tests/testosterone-total), [SHBG](https://www.test-well.com/tests/shbg-sex-hormone-binding-globulin), [DHEA-S](https://www.test-well.com/tests/dhea-sulfate)), and an ultrasound or [AMH](https://www.test-well.com/tests/amh) — the markers the [Women's Hormone Panel](https://www.test-well.com/tests/womens-hormone-panel) draws together. ## Perimenopause and Ovarian Reserve: Read the FSH, Not the Ratio As the ovaries' follicle pool declines, the pituitary raises FSH to recruit what remains, so day-2–4 FSH climbs through the late reproductive years and the menopausal transition — the **STRAW+10** staging system uses variable then persistently elevated FSH, alongside cycle changes, to mark those stages. That rising FSH pushes the LH:FSH ratio well below 1, but the ratio is the wrong way to look at it: the ASRM committee opinion on ovarian-reserve testing reads the **day-2–4 FSH together with estradiol** (a high estradiol can suppress FSH into the normal range and hide the signal) and treats **AMH** as the more stable marker because it barely varies across the cycle. Reserve markers predict how the ovaries respond to fertility treatment; they are poor predictors of whether a woman will conceive naturally, and a single high FSH is confirmed on a later cycle before anyone acts on it. ## In Men, the Ratio Is Not Used Men make LH and FSH continuously rather than in a cycle, and the question their levels answer is different: when total testosterone is low, is the problem in the testes or upstream in the pituitary? The Endocrine Society guideline reads the two hormones individually. **High LH and FSH with a low testosterone** point to primary hypogonadism — the testes are not responding (Klinefelter syndrome, prior injury, chemotherapy or radiation, mumps orchitis). **Low or normal LH and FSH with a low testosterone** point to secondary hypogonadism — a weak pituitary signal, with obesity, opioids, high prolactin, pituitary disease and exogenous testosterone or anabolic steroids the common causes; prolactin and iron studies are typical next tests. Dividing one by the other adds nothing to that reading. The [Men's Hormone Panel](https://www.test-well.com/tests/mens-hormone-panel) draws LH and FSH with total and free testosterone for exactly this question. ## What to Order and When - **For the ratio itself:** [LH](https://www.test-well.com/tests/luteinizing-hormone) ($36.99) and [FSH](https://www.test-well.com/tests/fsh) ($29.99) from one draw on cycle day 2–4; no fasting; one $6 fee covers the order. Add [estradiol](https://www.test-well.com/tests/estradiol) ($35.99) — a high estradiol changes how a "normal" FSH is read. - **Suspected PCOS:** the ratio plus the markers the criteria actually use — total and free testosterone, SHBG, DHEA-S, AMH — which the [Women's Hormone Panel](https://www.test-well.com/tests/womens-hormone-panel) bundles. Irregular cycles make the day-2–4 rule hard to follow; draw anyway and let the clinician interpret the whole set. - **Fertility planning or reserve:** [Women's Fertility Essentials](https://www.test-well.com/tests/female-fertility-panel) ($119.99) — AMH, FSH, LH, estradiol and progesterone — with FSH, LH and estradiol drawn on day 2–4. - **Perimenopause symptoms:** FSH and estradiol, repeated in a later cycle if the first is high; the ratio is incidental. - **A man with low testosterone:** LH, FSH and total testosterone (plus prolactin) — the [Men's Hormone Panel](https://www.test-well.com/tests/mens-hormone-panel); draw between 7 and 10 a.m. Results post to your portal in 1–4 business days with the reviewed reference ranges; the [calculator](https://www.test-well.com/tools/lh-fsh-ratio-calculator) takes the two numbers from any lab report. ## Frequently asked questions ### What is a normal LH to FSH ratio? On cycle day 2–4, FSH is usually at or slightly above LH, so a ratio of about 1 or below is the expected pattern. There is no single number that defines normal — the ratio is read with the absolute LH and FSH values and the cycle day, and studies disagree on where an elevated ratio starts (2, 2.5 or 3). ### Does an LH:FSH ratio above 2 mean I have PCOS? Not on its own. An LH-predominant ratio is common in PCOS, but the Rotterdam criteria and the 2023 international guideline diagnose PCOS from irregular ovulation, clinical or biochemical androgen excess, and ovarian morphology or AMH — two of three, after other causes are excluded. The ratio can support the picture; it cannot make or rule out the diagnosis, and a sample drawn near ovulation shows the same pattern in healthy women. ### Can I calculate the ratio from a blood test taken on any day? You can calculate it, but it only means something from a day 2–4 sample in a cycling woman not using hormonal contraception. LH rises several-fold around ovulation, so a mid-cycle ratio is mostly a measurement of the surge. If your cycles are irregular and there is no clear day 2–4, draw anyway and read the absolute values with estradiol, progesterone and androgens. ### What does a low LH:FSH ratio mean? Usually that FSH is high, not that LH is low. Rising day-2–4 FSH is how declining ovarian reserve and the menopausal transition show up on blood work, and the useful reading is the FSH value with estradiol and AMH — not the ratio. A single high FSH is repeated on a later cycle before conclusions are drawn. ### Does the LH to FSH ratio apply to men? No. In men, LH and FSH are interpreted individually against total testosterone: high LH and FSH with a low testosterone point to a testicular (primary) cause; low or normal LH and FSH with a low testosterone point to a pituitary or hypothalamic (secondary) cause. The Endocrine Society guideline follows that logic, with prolactin and iron studies as common next tests. ### Which tests do I order to get my LH:FSH ratio? LH ($36.99) and FSH ($29.99) from one draw on cycle day 2–4 — no fasting, one $6 fee per order, results in 1–4 business days. Add estradiol if you are reading FSH for reserve, or the Women's Hormone Panel if PCOS is the question, since the diagnosis rests on androgens and AMH rather than the ratio. ## Sources - [Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome. Hum Reprod 2004;19:41–47.](https://doi.org/10.1093/humrep/deh098) - [Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab 2023;108:2447–2469.](https://doi.org/10.1210/clinem/dgad463) - [Practice Committee of the American Society for Reproductive Medicine. Testing and interpreting measures of ovarian reserve: a committee opinion. Fertil Steril 2020;114:1151–1157.](https://doi.org/10.1016/j.fertnstert.2020.09.134) - [Harlow SD, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10 (STRAW+10). J Clin Endocrinol Metab 2012;97:1159–1168.](https://doi.org/10.1210/jc.2011-3362) - [Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103:1715–1744.](https://doi.org/10.1210/jc.2018-00229) - [MedlinePlus (NIH) — Luteinizing Hormone (LH) Levels Test](https://medlineplus.gov/lab-tests/luteinizing-hormone-lh-levels-test/) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-10-09. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md Canonical page: https://www.test-well.com/guides/lh-fsh-ratio Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.