---
title: LH to FSH Ratio Calculator
type: tool
url: "https://www.test-well.com/tools/lh-fsh-ratio-calculator"
date_published: 2026-10-09
free: true
---

# LH to FSH Ratio Calculator

> Enter LH and FSH from the same cycle day 2–4 draw and the calculator divides them to give the LH:FSH ratio. In that window FSH normally sits at or a little above LH, so a ratio of about 1 or below is usual. A ratio of 2 or more is common in PCOS but is not a diagnostic criterion, and a sample near the mid-cycle LH surge inverts the ratio.

## Key facts

| Fact | Value |
| --- | --- |
| Inputs | LH · FSH (same draw) |
| When to draw | Cycle day 2–4 |
| Usual early-follicular | ratio ≈ 1 or below |
| Cost | Free |

## For agents

See https://www.test-well.com/developers for the agent endpoints.

## Frequently asked questions

### What is a normal LH to FSH ratio?

In the early follicular phase (cycle day 2–4) FSH is usually at or slightly above LH, so a ratio around 1 or below is the expected pattern. There is no single cut-off that defines normal; the ratio is read alongside the absolute LH and FSH values and the cycle day.

### Does an LH:FSH ratio above 2 mean I have PCOS?

Not by itself. 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 hyperandrogenism and ovarian morphology or AMH — the ratio is supporting information. A ratio above 2 drawn near ovulation is also just the LH surge.

### Why does the cycle day matter so much?

LH rises several-fold for a day or two around ovulation, which flips the ratio in a woman with completely normal hormones. Day 2–4 of the cycle is the standard window because both hormones are at baseline. Hormonal contraception, pregnancy and breastfeeding also change both values.

### Does the LH:FSH ratio apply to men?

Not as a standard measure. In men, LH and FSH are interpreted individually against total testosterone: high LH with a low testosterone points to a testicular (primary) cause, low or normal LH with a low testosterone to a pituitary or hypothalamic (secondary) cause, per the Endocrine Society guideline.

## Related

- [lh](https://www.test-well.com/biomarkers/lh)
- [fsh](https://www.test-well.com/biomarkers/fsh)
- [estradiol](https://www.test-well.com/biomarkers/estradiol)
- [amh](https://www.test-well.com/biomarkers/amh)
- [total testosterone](https://www.test-well.com/biomarkers/total-testosterone)
- [luteinizing hormone](https://www.test-well.com/tests/luteinizing-hormone)
- [fsh](https://www.test-well.com/tests/fsh)
- [female fertility panel](https://www.test-well.com/tests/female-fertility-panel)
- [womens hormone panel](https://www.test-well.com/tests/womens-hormone-panel)

---

Canonical page: https://www.test-well.com/tools/lh-fsh-ratio-calculator
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.