Compare calendar dates and plan intervals with explicit counting rules for days, weeks, weekdays, and weekends.
Choose the right calculator
Check whether the tool counts or excludes the starting date and whether holidays are included. Calendar-day, business-day, and elapsed-hour questions are not always equivalent.
How these calculators are checked
Each tool shows its formula, assumptions, worked example, and limitations. We test default values, decimals, zero and invalid inputs, unit conversions, and rounding behavior. Learn more on How Our Calculators Work.
Important: Local holidays, business closures, work schedules, time zones, and daylight-saving rules may require additional handling.
This category and its linked calculators were reviewed by the DIY Cost Tools editorial team on October 4, 2026. Additional tools will be added without changing the category URL.