Ovulation Calculator — Fertile Days
Enter the first day of your last period and your cycle length to estimate when you ovulate and which days you are most fertile.
Ovulation Calculator
Fertile window and next period
Estimated ovulation2026-01-15
Fertile window starts2026-01-10
Fertile window ends2026-01-16
Next period expected2026-01-29
它是如何运作的
- Ovulation usually happens about 14 days before the next period.
- The fertile window is the 5 days before ovulation plus the day itself and one after.
- Irregular cycles make estimates less reliable.
- This is an estimate, not a method of contraception or medical advice.
Worked example: period started 1 March, 28-day cycle
- 1Ovulation: day 28 − 14 = day 14 → 15 March.
- 2Fertile window: 10–16 March.
- 3Next period: 29 March.
Most fertile around 13–15 March
Estimated ovulation day by cycle length
| Cycle length | Ovulation day |
|---|---|
| 24 days | Day 10 |
| 26 days | Day 12 |
| 28 days | Day 14 |
| 30 days | Day 16 |
| 32 days | Day 18 |
常见问题
When am I most fertile?
In the two or three days up to and including ovulation.
Can I use this to avoid pregnancy?
No. Calendar estimates are not reliable enough as contraception.
What if my cycle is irregular?
Use your average cycle length and consider ovulation tests or temperature tracking for more precision.
使用它没有广告
QuickCalc Pro 是一款一次性支付 4.99 美元的产品：任何地方都没有广告，您可以保存任何计算并在任何设备上再次打开。
30 天退款保证 · 通过 Paddle 安全结账
相关计算器
年薪转时薪计算器将年薪或月薪换算为时薪。输入薪资、每周工时和休假周数，立即得到准确的时薪。时薪转年薪计算器查看某个时薪换算成周薪、月薪和年薪各是多少。可自定义工时和休假周数。增值税计算器——加税或去税免费增值税计算器：按任意税率给净价加税，或从含税价中拆出增值税，同时显示净价、税额与含税价。小费计算器——计算小费并分摊账单免费小费计算器：选择 10%–20% 的比例，查看小费金额和总额，并按人数平均分摊。手机端也能用。折扣计算器——打折后的实付价格计算打折后的实付价格以及省下的金额。免费折扣计算器，支持任意折扣比例，立即显示节省金额。货币汇率转换器——实时汇率在欧元、美元、英镑、日元等货币之间实时换算。免费货币转换器，无需注册。
查看全部 32 个计算器