Implantation Calculator when it happens, and when to test
- 6 to 12days after ovulation
- 84%implant on days 8 to 10
- Day 14a reliable test
Days 8 to 10: Wilcox and colleagues, New England Journal of Medicine, 1999.
Work out your implantation days
Count from my
Which day did you ovulate?
Tap a day in the strip above and your implantation days appear here.
ExampleOvulation on 21 October 2026. Today is day 5 after ovulation. If this cycle works, your due date is about 14 Jul 2027.
- Implantation most likely
- Thu 29 – Sat 31 Oct
- Possible window
- 27 Oct – 2 Nov
- Earliest home test
- Sun 1 Nov
- Reliable test
- Wed 4 Nov
- Ovulation 0 Wed21 Oct
- 1 Thu22 Oct
- 2 Fri23 Oct
- 3 Sat24 Oct
- 4 Sun25 Oct
- 5 Mon26 Oct
- 6 Tue27 Oct
- 7 Wed28 Oct
- 8 Thu29 Oct
- Most likely 9 Fri30 Oct
- 10 Sat31 Oct
- Early test 11 Sun1 Nov
- 12 Mon2 Nov
- 13 Tue3 Nov
- Reliable test 14 Wed4 Nov
- 15 Thu5 Nov
- 16 Fri6 Nov
The first two weeks
From ovulation to implantation
A tiny journey of about a week, from the fallopian tube to the lining of the womb.
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Day 0
Ovulation
An egg is released and lives for about a day.
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Day 1
Fertilisation
If a sperm reaches it, the egg is fertilised in the fallopian tube.
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Day 3
Morula
A ball of about 16 cells travels slowly towards the womb.
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Day 5
Blastocyst
It reaches the womb as a hollow ball of a hundred or more cells.
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Day 9
Implantation
It settles into the lining of the womb, most often 8 to 10 days after ovulation.
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Day 12
hCG rises
The pregnancy hormone starts to build up. This is what a test looks for.
Implantation bleeding
Is it implantation spotting, or your period?
Many women notice no spotting at all, and that is completely normal. If you do, these are the usual differences.
| What to look at | Implantation spotting | A period |
|---|---|---|
| When | 6 to 12 days after ovulation, a few days before your period is due | On the day your period is due |
| Colour | Light pink or brown | Bright to dark red |
| How much | A few spots, not enough to fill a pad | Starts light, then gets heavier |
| How long | A few hours to two days | Three to seven days |
| Cramps | Mild and brief, or none at all | Often stronger, and they last longer |
| Clots | No | Sometimes |
Pregnancy tests
When a test will tell you the truth
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10 to 11days after ovulation
Earliest
A sensitive home test may pick up the pregnancy hormone. A negative this early is not final.
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14days after ovulation
Reliable
The day your period is due. Most home tests give a trustworthy answer from here.
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9 to 12days after an IVF transfer
After IVF
Your clinic's blood test is the one to trust. A home test can be fooled by the trigger injection.
Questions
Implantation, answered
TimingHow many days after ovulation does implantation happen?
Between 6 and 12 days after ovulation. In a well known study of women trying to conceive, 84 percent of pregnancies implanted on day 8, 9 or 10 (Wilcox and colleagues, 1999).
TimingCan implantation happen late?
It can happen up to about 12 days after ovulation, but after day 10 it is less common. If your cycle is long or irregular, you may simply have ovulated later than you think.
SignsWhat does implantation bleeding look like?
A few spots of light pink or brown blood, lasting a few hours to two days, around 6 to 12 days after ovulation. Many women notice no spotting at all, and that is completely normal.
SignsCan I feel implantation happening?
Most women feel nothing. Some notice a mild, short cramp or a little spotting. Early pregnancy signs are very like the days before a period, so they cannot tell you on their own.
TestingWhen can I take a pregnancy test?
A sensitive test may work from about 10 or 11 days after ovulation, but the answer is reliable from the day your period is due, about 14 days after ovulation.
TestingWhy was my early test negative?
The hormone a test looks for only builds up after implantation, and takes a few days to reach a level a test can see. Test again on the day your period is due, or a few days later.
After IVFWhen does implantation happen after an IVF transfer?
Sooner than in a natural cycle, because the embryo is placed straight into the womb: usually 1 to 3 days after a day 5 transfer, and 3 to 4 days after a day 3 transfer.
After IVFShould I test at home after an IVF transfer?
It is better to wait for your clinic's blood test, 9 to 12 days after the transfer. The trigger injection used before egg collection contains the same hormone, so an early home test can be falsely positive.
Support in the two week wait
The two week wait is hard. You do not have to do it alone.
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The right test, on the right day
Which day to test, and when a blood test tells you more than a home test.
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A result, talked through
A positive, a negative or a faint line: we go through what it means with you.
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A plan for what comes next
An early scan if you are pregnant, and tests or treatment such as IUI or IVF if not.