Ovulation check (day 21 progesterone)
One timed blood test that shows whether you ovulated this cycle. We help you place the day, and a doctor explains the number.
The ovulation check is a single progesterone blood test taken about seven days after you think you ovulated, often day 21 of a 28-day cycle. A clearly raised mid-luteal progesterone is the standard laboratory way to confirm an egg was released. It costs $59, with an optional 20-minute doctor consult (+$59). Collect at an accredited Australian centre, or choose a home kit or a nurse visit at checkout (options below).
What it measures
- Progesterone (day 21): the hormone made by the corpus luteum, the structure left in the ovary after an egg is released. It only rises meaningfully once ovulation has happened, which makes a well-timed level a useful yes-or-no marker. "Day 21" assumes a 28-day cycle; the real target is the middle of your luteal phase, whatever day that is for you.
Who it's for
Anyone who wants to know whether ovulation is actually happening: you have regular periods but nothing has happened yet, your cycles are irregular and you cannot tell, or a doctor suggested a second collection after a female hormone panel or AMH and fertility panel. It is for adults aged 18 and over, and is not designed for women using contraception that suppresses ovulation (the combined pill, patch or ring, the injection, the implant and most progestogen-only pills). On a hormonal IUD many women still ovulate, so the result may still be interpretable; ask your doctor.
What you'll learn, and what you won't
You'll learn whether your progesterone reached a level consistent with ovulation in the cycle you tested, reported in plain English against your laboratory's range. If it did, that rules out one common cause of difficulty conceiving. If it did not, it is a prompt for your doctor to look at timing and at the hormones that drive ovulation.
What one test cannot do: it cannot show that ovulation happens every cycle, pinpoint the day you ovulated, or predict whether you will conceive. A low reading can simply mean the timing was off. A blood test is one input to a doctor's assessment, not a diagnosis on its own.
Reference ranges and what they mean
| Marker | Typical adult range | What it usually means |
|---|---|---|
| Progesterone, mid-luteal | Above about 30 nmol/L is widely used in Australia as consistent with ovulation; 15 to 30 nmol/L is a borderline band. | Clearly raised: ovulation very likely occurred. Borderline: your doctor reads it with the timing of the sample, and it is often repeated. Low: ovulation may not have happened, or the sample was outside the window. |
| Progesterone, follicular phase | Low, typically under about 5 nmol/L | Normal before ovulation. A low value only means something if the blood was taken in the luteal window. |
Ranges vary by laboratory; your report shows the range your lab uses. Typical ranges on this page are drawn from Pathology Tests Explained (RCPA) and the sources listed below.
How to time it
Progesterone peaks around seven days after ovulation, so aim for that window rather than a fixed date. With a regular 28-day cycle, day 21 works (day 1 is the first day of full bleeding). With a longer or shorter regular cycle, count back seven days from when your next period is due: a 32-day cycle points to about day 25, a 25-day cycle to about day 18.
If you use ovulation strips or a cycle app, collect about seven days after your positive surge or predicted ovulation day. If your cycles are irregular, one day 21 sample can easily miss the window; your doctor may suggest weekly samples until your period arrives. We help you place the day when you order.
What the result can lead to
A level consistent with ovulation lets you and your doctor turn attention elsewhere. A low or equivocal level is usually repeated next cycle with tighter timing. If two well-timed samples stay low, your doctor may look at FSH, LH, prolactin and thyroid function, or suggest 28-day cycle mapping, which tracks oestradiol and progesterone across a whole cycle rather than one day of it.
Blood test or ovulation strips?
Urine strips detect the LH surge that precedes ovulation: they predict. A positive strip shows your body is trying to ovulate, not that an egg was released. A progesterone blood test measures what happened afterwards: it confirms, as closely as a blood test can. Rarely a follicle luteinises without releasing an egg, which raises progesterone anyway, and only ultrasound tracking picks that up. Use strips to time intercourse and place the blood test, then use the blood test to confirm the cycle was ovulatory.
When to do this test
About seven days after ovulation, often day 21 of a 28-day cycle; adjust for your cycle length or collect seven days after a positive ovulation strip. Any time of day, no fasting. If you are using contraception that suppresses ovulation, this test is not informative. Do not stop contraception just to test; if you are planning to stop anyway, wait until you have had a natural period first.
How it works
- Order online. A KnowLuna women's health doctor requests the test at no extra charge, or upload a request your own doctor has signed.
- Collect at an accredited centre near you on the day we help you choose, or choose a home kit or a nurse visit (options below).
- Results are usually ready within a few business days, explained in plain English in your account, with an optional 20-minute doctor consult.
Choose how you collect
Every option is the same accredited test and the same report. Pick what suits you at checkout; the fee, if any, is added to either pathway price.
A quick draw at an accredited pathology collection centre near you. Usually under ten minutes. Included.
Lancet kit posted to you with an Express return satchel. If the lab cannot test your sample we send a replacement kit at no charge.
A near-painless device draws a small sample from the upper arm, with far fewer failed samples than a finger-prick. Express return satchel included.
A registered nurse comes to your home or workplace for a standard blood draw. Metro areas of capital cities; other locations on request.
Common questions
What day should I do a progesterone test?
About seven days after ovulation. For a regular 28-day cycle that is day 21. For other lengths, count back seven days from the day your next period is due, or collect seven days after a positive ovulation strip. If your cycles are irregular, we help you place the day, or your doctor may suggest weekly samples.
What progesterone level confirms ovulation?
In Australia a mid-luteal progesterone above about 30 nmol/L is widely taken as consistent with ovulation, and your report shows the range your lab applies. Between about 15 and 30 nmol/L is a borderline band that your doctor reads with the timing of the sample, and it is often repeated.
Can I do a day 21 test with an irregular cycle?
Yes, but "day 21" is only right for a 28-day cycle. With irregular cycles a single sample may miss the window. Options are to time it from a positive ovulation strip, or to collect weekly until your period arrives so the peak is captured. Your doctor will suggest the approach that fits your pattern.
How is an ovulation blood test different from an ovulation strip?
A strip detects the LH surge in urine before ovulation, so it predicts. A progesterone blood test measures the hormone made after an egg is released, so it confirms. Strips can show a surge without a release, and some women with PCOS get misleading strip results. Many women use both.
Does the ovulation check need fasting?
No. Progesterone is not affected by food, so eat and drink normally and collect at any time of day. What matters is the day in your cycle, not the hour. The test is not informative while you are using contraception that suppresses ovulation, since the result reflects the contraception rather than your natural cycle; on a hormonal IUD, where most women still ovulate, your doctor can advise.
Sources and further reading
- Pathology Tests Explained (RCPA): progesterone
- Better Health Channel: ovulation
- Pregnancy, Birth and Baby: ovulation and fertility
- Healthdirect: about infertility
General information only, not medical advice. A test result is one input to a doctor's assessment, not a diagnosis on its own, and every abnormal result is followed up by a KnowLuna doctor. If your symptoms are severe or sudden, see a doctor promptly. Read our medical disclaimer.
Related
Then plan the next cycle.