Does Days in Month upload my file or text to Tool-You servers?

No. Days in Month runs in this browser tab. Files stay on the device. Limit note: Month 1–12. Leap flag only meaningful for February.

Should I use Leap Year Check instead of Days in Month?

Use Days in Month when you need Days in a month; leap flag for February. Use Leap Year Check when you need Is leap year? Plus next/previous leap years. They share a category (Date & time) but not the same job.

Days in Month

Days in a month; leap flag for February.

Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails.

What Days in Month does

Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails.

Days in Month sits in the Date & time group on purpose. It is not Leap Year Check (Is leap year? Plus next/previous leap years.) and not Calendar Quarter (Q1–Q4 plus quarter start, end, and day count.). Choose this page when you need Days in a month; leap flag for February. If you stretch Days in Month into a neighbor’s job, the result will look wrong even though the site chrome looks the same.

How to use Days in Month

Confirm you need Days in Month, not Leap Year Check (Is leap year? Plus next/previous leap years.). Address: /datetime/days-in-month.
Enter the numbers or dates Days in Month uses. Days in a month; leap flag for February.
Read the result as Days in Month defines it — not as Calendar Quarter (Q1–Q4 plus quarter start, end, and day count.). Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails.
Days in Month is an estimate in the browser, not professional advice. Month 1–12. Leap flag only meaningful for February.
Need a different formula? Try Calendar Quarter (Q1–Q4 plus quarter start, end, and day count.) instead of stretching Days in Month.

When not to use Days in Month

Skip Days in Month when a neighbor tool matches better — start with Leap Year Check or Calendar Quarter — or when the description already warns the job will fail. In the tool’s own words: Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails.

Questions about Days in Month

What does Days in Month do that other Date & time pages on this site do not?: Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails. Short version: Days in a month; leap flag for February.
Does Days in Month upload my file or text to Tool-You servers?: No. Days in Month runs in this browser tab. Files stay on the device. Limit note: Month 1–12. Leap flag only meaningful for February.
Should I use Leap Year Check instead of Days in Month?: Use Days in Month when you need Days in a month; leap flag for February. Use Leap Year Check when you need Is leap year? Plus next/previous leap years. They share a category (Date & time) but not the same job.
What are the limits of Days in Month?: Month 1–12. Leap flag only meaningful for February. Also: Returns 28–31 for a year and month. Leap is 1 only in February of a Gregorian leap year. Unlike Leap Year this is one month, not the whole year. Month outside 1–12 fails.