Is Conception Calculator free to use?

Yes, Conception Calculator is completely free. No account, no sign-up, and no hidden fees required.

Is my data safe when using Conception Calculator?

Your data never leaves your device. All processing happens locally in your browser — nothing is uploaded to any server.

Health Tools

Estimate ovulation date, fertile window, and most likely conception window from your last menstrual period and cycle length

Trusted by 10k+ developers

First Day of Last Period (LMP)

Average Cycle Length (days)

Estimated Ovulation Date

Monday, July 13, 2026

Fertile WindowJul 8 – Jul 14

Most Likely ConceptionJul 12 – Jul 14

If Conceived, Due DateApr 5, 2027

• Ovulation typically occurs 14 days before the next expected period
• The fertile window is the 6 days ending on ovulation day (sperm survive up to 5 days)
• Cycle lengths vary; track several cycles for a more accurate estimate
• Consult a healthcare provider for fertility planning or medical guidance

Calculate your Body Mass Index (BMI) and Basal Metabolic Rate (BMR) with health insights

Estimate daily calorie needs and macronutrient distribution for your fitness goals

Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle, plus daily TDEE for any activity level

Calculate body fat percentage using the US Navy method — metric and imperial, with fat mass and lean mass breakdown

Estimate your blood alcohol content with the Widmark formula — based on weight, gender, drinks, and elapsed time

Calculate your pregnancy due date with Naegele's rule — current week, trimester, and days remaining from LMP or conception

Find the best time to wake up or go to sleep based on 90-minute sleep cycles to wake up refreshed

Calculate your pregnancy due date, current week, and trimester based on last menstrual period or conception date

We build free tools based on community feedback. If there's a utility that would improve your workflow, suggest it today!