Period Calculator
Estimate upcoming period dates from last period and cycle length.
This page is an editable estimator with realistic defaults so you can model your own situation in minutes.
Next period date is last period date plus average cycle length, repeated for future cycles.
Treat the result as a planning estimate and verify important numbers with the relevant official source before acting.
| Cycle 1 | Jun 6, 2026 to Jun 10, 2026 | |
|---|---|---|
| Cycle 2 | Jul 4, 2026 to Jul 8, 2026 | |
| Cycle 3 | Aug 1, 2026 to Aug 5, 2026 |
Assumptions
- Cycles can vary because of stress, illness, travel, medication, pregnancy, or health conditions.
- See a clinician for unusual bleeding, severe pain, or major cycle changes.
How this calculator works
Formula used
Next period date is last period date plus average cycle length, repeated for future cycles.
Example calculation
Plug in your own numbers and the result updates instantly. Next period date is last period date plus average cycle length, repeated for future cycles.
Period Calculator FAQ
Is this period calculator medical advice?
No. It is an educational estimate only and does not replace an OB-GYN, midwife, fertility specialist, pediatric clinician, or emergency care.
Why might my actual dates or recommendations differ?
Cycle length, ovulation timing, ultrasound dating, implantation timing, multiples, medical history, and clinician judgment can change pregnancy and fertility estimates.
Should I confirm results with a clinician?
Yes. Confirm pregnancy dating, weight gain, cycle concerns, fertility timing, or health decisions with a qualified healthcare professional.