Cycle Calculator: Estimate Your Next Menstrual Cycle Date
Estimate the next cycle date from a start date and cycle length.
Health and wellness
Health
Inputs
Cycle Calculator
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Result date
2026-05-10
Total days changed
28
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Save scenario A, change a few inputs, then save scenario B.
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Change one or two inputs to compare a second scenario before using the number.
Need more detail?
Formula, examples, and FAQ stay tucked away until you need them.
FXFormula ExplanationThe core logic behind the numbers on this page.+
Our cycle calculator uses a simple formula to estimate the next cycle date by adding calendar months first, then days, using a UTC date calculation to ensure accuracy. This approach helps avoid time-zone drift and provides a reliable estimate. The calculator takes into account the start date and cycle length to provide a personalized estimate. You can adjust the cycle length to match your individual cycle duration for a more accurate estimate.
USEHow to UseA short path from input to result.+
- Enter the requested inputs.
- Keep any editable rule or rate fields aligned with your situation.
- Review the result and notes before using the estimate.
EXExamplesReference scenarios to sanity-check your inputs.+
Adjust the defaults to match your scenario, then calculate the estimate.
FAQFAQCommon edge cases and quick clarifications.+
How accurate is the cycle calculator?
This calculator provides an estimate based on the input values. It's essential to review the result and notes before using the estimate, especially for critical decisions.
Can I adjust the cycle length?
Yes, you can adjust the cycle length to match your individual cycle duration. This will give you a more accurate estimate of your next cycle date.
Is this calculator suitable for all users?
This calculator is designed for general use. However, if you have specific health or medical concerns, consult a healthcare professional for personalized advice.
What if I have an irregular cycle?
If you have an irregular cycle, you can use this calculator as a starting point and adjust the cycle length to better suit your needs.
Can I use this calculator for medical purposes?
While this calculator can provide a helpful estimate, it's essential to consult a healthcare professional for accurate medical advice and diagnosis.