EEasynivo
Free health planning tool

Ovulation & Fertile Window Calculator

Estimate ovulation, the fertile window and the next period from a regular cycle.

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Result

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Enter values and select Calculate.

Method and assumptions

Estimates ovulation as 14 days before the next period and shows the five days before through one day after.

Important limitations

Cycle timing varies, especially with irregular periods. Do not use this estimate alone for contraception.

Official references

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Sources & methodology

Calculation method
Estimates ovulation as 14 days before the next period and shows the five days before through one day after.
Evidence basis
Published health guidance combined with a simplified planning estimate.
Applies to
No statutory reference year. Results use the values and assumptions entered now.
Last reviewed
Limitations
Cycle timing varies, especially with irregular periods. Do not use this estimate alone for contraception.

Sources

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Content basis and verification

· Calculations run in your browser. Check the formula and assumptions on this page, and confirm important financial, tax, medical or legal decisions against current official guidance.