Pediatricians prefer weekly tracking for infants under 4 months because babies develop rapidly and hit milestones on weekly schedules. Growth spurts, feeding patterns, sleep cycles, and developmental leaps (like smiling, cooing, rolling) all follow predictable weekly timelines. Weekly tracking helps identify delays early.

Yes, absolutely. All leap days and calendar variations are automatically handled by our underlying date calculation engine. Whether your birth year was a leap year or not, and regardless of how many leap years have occurred since, the calculation remains accurate.

Calculate your baby's age in weeks weekly or bi-weekly. Compare the results with standard pediatric growth charts that show expected weight, height, and developmental milestones for each week. Many parents keep a journal noting their baby's weekly age alongside observations.

While this calculator shows age from birth date, you can use it to calculate weeks from conception date or last menstrual period (LMP). However, for pregnancy-specific features like trimester breakdowns and fetal development milestones, consider using a dedicated pregnancy calculator.

Yes, completely. All calculations happen in your browser using JavaScript - no data is sent to our servers. Your date of birth is never stored, logged, or shared. The calculator works entirely offline once the page loads.

For baby tracking, weekly or bi-weekly updates work well. For fitness goals, calculate every week on the same day (like Monday mornings). For general interest, monthly calculations are sufficient. The frequency depends on your specific use case.

If you know the approximate date (even just month and year), you can still get a useful estimate. For babies adopted internationally or in situations where exact birth dates are unknown, use the estimated date provided by medical professionals.