What the site is for
These tools answer practical questions such as how many days separate two dates, what date falls a month from now, which weekdays occur in a range, or which ISO week contains a date. Each page states the counting rule and calls out edge cases that can change the answer.
How calculations are maintained
The site uses shared, tested calendar functions for parsing, range checks, leap years, month-end clamping, ISO weeks, and weekday counting. Page-specific explanations and examples are written for the task on that page rather than copied across every calculator.
Calculations happen in the browser. Plain Dates currently has no user accounts, server-side date storage, or user profile system.
Accuracy and limits
Automated examples cover month ends, leap years, reverse ranges, inclusive endpoints, duplicate holidays, ISO year boundaries, and ICS exclusive end dates. Even so, a general calculator cannot determine which legal, financial, medical, employment, or administrative rule applies to a particular situation.
Corrections
If a calculation or explanation appears wrong, include the page URL, inputs, expected result, and the rule or source you believe applies when contacting us. Reproducible reports are the fastest to investigate.