Why the days before ovulation matter most
Sperm can wait in the reproductive tract for up to five days; the egg survives only about 24 hours after release. So the winning strategy is to have sperm already present when ovulation happens, which means sex before ovulation, not after. Per-day conception probabilities from the Wilcox study reflect exactly that: highest on the day before ovulation and on ovulation day, useful from five days before, close to zero afterwards.
Turning the window into a plan
The every-other-day plan starts on the first fertile day and runs through the day after predicted ovulation. It guarantees sperm are present across the whole window even if ovulation comes a day early or late. If your prediction is uncertain, confirm ovulation with test strips; when a strip turns positive, that day and the next are your best two. For irregular cycles use the irregular periods ovulation calculator, and once you have ovulated, switch to counting DPO with how many DPO am I.
Frequently asked questions
When is the best time to have sex to get pregnant?
The day before ovulation and ovulation day itself. In the landmark Wilcox study of healthy couples, the per-day chance of conception peaked at about 30% on those two days, was around 10 to 15% five and four days before, and fell to near zero the day after ovulation. The calculator turns those days into dates for your cycle.
How often should we have sex when trying to conceive?
Every day or every other day across the fertile window both work well. Every other day keeps a healthy sperm count and takes the pressure off; daily does not lower the chance for most couples. What matters is covering the two to three days before ovulation, since the egg only lives about a day after release.
Can I get pregnant right after my period?
Sometimes. With a short cycle of 21 to 24 days, ovulation can come within a week of the period ending, and sperm can survive up to five days, so sex in the last days of a period can lead to pregnancy. The calculator uses your actual cycle length to place the window rather than assuming day 14.
What is the best time of day to conceive?
There is no strong evidence that time of day matters. Sperm quality is slightly higher in the morning in some studies, but the effect is small compared with getting the day right. Choose whatever time you will actually keep to.
How long does it usually take to get pregnant?
Roughly 80% of couples under 35 conceive within a year of well-timed sex, and about half within six months. If you are under 35 and have been trying for a year, or over 35 and trying for six months, it is time to see a doctor.
These calculators give estimates based on cycle averages and standard formulas. They are for general information only and are not medical advice. For anything concerning your health or pregnancy, talk to a qualified healthcare provider.