Start with your last period
Enter your bleeding days, not the date of sex. Then explore that date on the calendar.
Cycle length
Period length
Ovulation day
Period days logged: 0 days
Your period dates
Tap every day you bled to add or remove it
Start with your last period
Could I be pregnant after unprotected sex?
Look back at your estimated fertile days and understand your next steps. A calendar cannot confirm or rule out pregnancy.
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Understand the timing. Know the limits.
01
Enter period days
Mark each day of your last period. Earlier periods help personalize the model, but cannot make it certain.
02
Look back at the date of sex
Navigate to that month, then hover or hold the date for an estimated phase. The cycle summary shows today.
03
Plan a pregnancy test
Test from the first day of a missed period. If you do not know when it is due, test at least 21 days after the most recent unprotected sex.
No data stored.
periods.day has no accounts, cookies, analytics, or saved cycle data. Your entries live only in a link you can share. Nobody else can edit your entries.
Who made this?
Hello! I wanted to understand my body without sharing my data with advertisers. I also wanted to share knowledge about women's health. Feel free to share this website if you find this useful!
Questions after unprotected sex
What should I do after recent unprotected sex?
If it was within the last 5 days, ask a pharmacist or sexual-health service about emergency contraception now. Options and time limits vary; sooner is better. Do not wait for this estimate. If it was longer ago, still seek advice. Emergency contraception guidance
Can this tell me whether I am pregnant?
No. The calendar estimates timing from period dates. It does not know when you actually ovulated, whether fertilization occurred, or whether you are pregnant. Use a pregnancy test at the appropriate time.
Can I get pregnant outside the fertile window?
Yes. Ovulation can shift, even with regular cycles, and sperm can survive for several days. A predicted lower-fertility day does not rule out pregnancy.
When should I take a pregnancy test?
From the first day of a missed period, or at least 21 days after the most recent unprotected sex if you do not know when your period is due. An early negative result may need repeating. Seek medical advice if your period remains absent.
How are fertility percentages calculated?
These estimates use pregnancy data from 221 women who were actively trying for a baby and had stopped using contraception. They recorded each day whether they had intercourse. Li, Wilcox and Dunson (2015, Table 3) used a statistical model to estimate the chance of a clinical pregnancy from one act on a given cycle day. This does not mean the women had sex once every day. The study did not record whether ejaculation occurred inside the vagina. These figures therefore do not estimate the risk with withdrawal. Our calendar shifts the study’s curve to match the calculated ovulation day or the cycle day you set. This is an approximation, not a validated personal prediction. Days before the table starts use its first value. The percentages are population estimates, not your personal odds or a contraceptive method. Li, Wilcox & Dunson (2015)