How are weeks and days counted?

The tool counts the exact whole days between the two dates, then divides by seven. The result shows complete weeks plus the remaining days, and also the total weeks and total days for convenience.

Why use weeks instead of months?

Weeks are commonly used for infant age (such as a baby's age in weeks) and for pregnancy and milestone tracking, where months can be ambiguous because they vary in length.

How do I convert days to weeks and days?

Divide the total number of days by 7. The whole-number part is the number of weeks and the remainder is the leftover days. For example, 100 days is 14 weeks and 2 days.

Is a baby's age usually given in weeks?

Yes. For the first months of life, paediatricians, growth charts and pregnancy tracking typically use weeks because they are more precise than months, which vary in length.

Is my date of birth uploaded?

No. Everything is computed locally in your browser — your dates never leave your device and nothing is stored.

What is the Age in Weeks and Days Calculator?

Free age in weeks and days calculator — enter a date of birth or start date and an end date to get the exact age in weeks plus leftover days, total weeks, and total days. Runs entirely in your browser, nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Age in Weeks and Days Calculator

Name: Age in Weeks and Days Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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The Age in Weeks and Days calculator expresses any age or date span as whole weeks plus the leftover days. This is the format used for infant age, pregnancy and milestone tracking, and any situation where months are too coarse or vary too much in length. Enter a date of birth (or any start date) and an end date to get the breakdown instantly.

How it works

The tool counts the exact number of whole days between the start and end dates, then divides that total by 7. The integer part of the division is the number of complete weeks, and the remainder is the leftover days (0 to 6). It also shows the raw total weeks (as a decimal) and the total days, so you have every form of the answer at once. The end date defaults to today but can be set to any later date.

Example

A baby born on 1 January 2026, measured on 12 March 2026:

The span is 70 days. 70 ÷ 7 = 10 with a remainder of 0, so the baby is 10 weeks and 0 days old — exactly 10 weeks.

Output	Value
Weeks	10
Days	0
Total days	70

Why weeks (not months) matter for infants and pregnancies

Months are ambiguous — they contain 28, 29, 30, or 31 days and don’t divide evenly. A six-week-old infant and a “one-and-a-half-month-old” are the same child, but one description is precise and the other requires the listener to guess. For this reason:

Paediatricians record a newborn’s age in weeks for the first several months, because growth and development milestones are keyed to weeks, not calendar months.
Neonatal and premature care is entirely week-based. A baby born at 30 weeks gestation and now 8 weeks old has a “corrected age” of 38 weeks — a calculation that only makes sense in weeks.
Pregnancy dating uses gestational weeks from the last menstrual period, making a pregnancy calculator and a baby age calculator essentially the same tool.
Fertility and IVF records track days and weeks from egg retrieval or transfer.

Other uses

The calculator works for any date span, not just infant ages. Use it to track a project duration in weeks and days, measure how long a subscription has been running, calculate the age of a business or a piece of equipment, or simply answer “how many weeks between these two dates?”

All arithmetic runs in your browser, so your dates never leave your device.