Ovulation calculator
This free ovulation calculator uses the start date of your last menstrual period and your average cycle length to estimate your ovulation day, the most fertile days for conceiving and the approximate date of your next period. Pick the date of your last period and enter your cycle length (usually 28 days) and you'll instantly see your fertile window. If you know your luteal phase length you can adjust it, and the calculator also shows a calendar for your next 3 cycles. The tool is helpful when planning a pregnancy in Tbilisi, Baku, Yerevan or Marneuli, but results are estimates and don't replace advice from a doctor.
How the calculation works
The calculator relies on the luteal phase lasting about 14 days: ovulation happens roughly 14 days before your next period. So the ovulation day = start of last period + (cycle length − luteal phase). The luteal phase differs between women (typically about 12–16 days), so the default 14 days can be changed. The highest chance is the 2 days before ovulation plus ovulation day. The fertile window starts 5 days before ovulation and ends on ovulation day, because sperm can survive for several days. Everything runs in your browser and no data is sent anywhere.
Worked example
If your last period started on 1 August and your cycle is 28 days, ovulation falls around 15 August, the fertile window runs 10–15 August, and your next period is expected around 29 August. A different cycle length changes the result.
Frequently asked questions
How is the ovulation day calculated?
Ovulation happens about 14 days before the next period, so those 14 days are treated as fixed.
What is the fertile window?
It's the days most favourable for conceiving — the 5 days before ovulation plus ovulation day itself.
How accurate is the result?
The result is an estimate. Real ovulation can shift due to stress, illness and hormonal changes.
Is my data stored?
No — the calculation runs in your browser and nothing is sent to a server.
Can I use this as contraception?
No, the calendar method is not reliable contraception. Talk to a doctor for protection.
What if my cycle is irregular?
Enter the average length of your last 3–6 cycles and treat the result as a rough guide. With irregular cycles, ovulation (LH) tests are more useful — in Georgia, Azerbaijan and Armenia they are sold in pharmacies.
Which doctor should I see?
A gynecologist. If pregnancy doesn't happen after a year of regular trying (6 months if you are over 35), a gynecologist or fertility specialist (reproductologist) consultation is recommended.