Compare calculators
Both calculators run independently β change the inputs on either side to compare results.
Ovulation & Fertile Window Calculator
Pinpoint your likely ovulation day and fertile window from your cycle length, luteal phase, and the cycle day you're on today β based on the fixed-luteal-phase method.
Days until ovulation
8 days
More than 6 days until ovulation means you are before the fertile window. Conception is unlikely now; the window opens about 5 days before your predicted ovulation.
Counts days until ovulation as (cycle length minus luteal phase) minus current cycle day; the fertile window spans the 5 days before ovulation through ovulation day itself.
Conception Date Estimate Calculator
Estimate how many days ago conception likely occurred from your last menstrual period, corrected for your cycle length and luteal phase rather than assuming day-14 ovulation.
Days since estimated conception
42 days
Key differences
| Ovulation & Fertile Window Calculator | Conception Date Estimate Calculator | |
|---|---|---|
| Category | Pregnancy | Pregnancy |
| Inputs required | 3 | 3 |
| Result | Days until ovulation (days) | Days since estimated conception (days) |
| What it does | Pinpoint your likely ovulation day and fertile window from your cycle length, luteal phase, and the cycle day you're on today β based on the fixed-luteal-phase method. | Estimate how many days ago conception likely occurred from your last menstrual period, corrected for your cycle length and luteal phase rather than assuming day-14 ovulation. |