Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
Pregnancy
Fertility & Ovulation Calculator
Predicts how many days until your fertile window opens from how many days ago your last period started, your average cycle length, luteal phase, and how regular your cycles are.
Fill in the required fields to see your result.
Pregnancy
Ovulation & Fertility Calculator
Predicts how many days until ovulation and your fertile window from how many days ago your last period started, your cycle length and luteal phase — and can project a later cycle.
Fill in the required fields to see your result.
Key differences
| Fertility & Ovulation Calculator | Ovulation & Fertility Calculator | |
|---|---|---|
| Category | Pregnancy | Pregnancy |
| Inputs required | 4 | 4 |
| Result | Ovulation Prediction | Ovulation Prediction |
| What it does | Predicts how many days until your fertile window opens from how many days ago your last period started, your average cycle length, luteal phase, and how regular your cycles are. | Predicts how many days until ovulation and your fertile window from how many days ago your last period started, your cycle length and luteal phase — and can project a later cycle. |