Fertile Window Calculator to Get Pregnant

To conceive faster, the key is concentrating your attempts in the fertile window — the window around ovulation. Enter the date of your last period and your cycle length to see your highest-chance days.

How to increase your chance per cycle

The American Society for Reproductive Medicine defines the fertile window as the 6-day interval ending on the day of ovulation, and puts peak fecundability in the 2 days before ovulation. Its recommendation on frequency is specific: reproductive efficiency “is highest when intercourse occurs every 1 to 2 days during the fertile window,” with results from less frequent intercourse — 2 to 3 times a week — described as “nearly equivalent.” MedlinePlus reaches the same place from the other direction: having sex every other day or every third day works just as well as every day.

There’s no need to “save up” for the right day. ASRM notes that abstinence intervals as short as 2 days are associated with normal sperm density, while after 10 days or more semen parameters begin to deteriorate.

Worked example

Last period started May 1, 28-day cycle:

• Ovulation: May 15
• Highest-chance window: May 13 to 15
• Strategy: intercourse on May 13, 14, and 15

How long it usually takes

Timing helps, but patience is part of the arithmetic. ASRM estimates that approximately 80% of couples conceive in the first 6 months of trying. In PRESTO, a preconception cohort of 2,962 U.S. and Canadian couples, 58.1% conceived within 6 cycles and 74.9% within 12 — and among those who had been trying for no more than one cycle at enrollment, 63.9% and 78.7%.

What actually helps

Beyond timing the fertile window, some habits support couple fertility:

• Keeping a healthy weight and balanced diet.
• Not smoking and cutting back on alcohol.
• Starting folic acid already while trying, as guided by your doctor.
• Caring for sleep and stress levels.

If attempts continue for a while, see the trying-to-conceive calculator to know when to seek help. To focus on the central day, use the ovulation calculator.

This calculator is informational and gives an estimate. Difficulty conceiving deserves evaluation by a gynecologist or reproductive specialist.