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Start with a focused tool
Live tools include the formula, a checked example, and documented assumptions.
Date Difference Calculator
Count the exact calendar days and elapsed weeks between two dates.
Hours to Decimal Calculator
Convert clock hours and minutes to decimal hours, or turn a decimal back into hours and minutes.
Hours Calculator
Find hours between two clock times, including overnight shifts, then subtract an unpaid break.
Business Days Calculator
Count weekdays between two dates, optionally excluding a versioned US federal holiday set.
Date Calculator
Add or subtract days, weeks, months, or years from a calendar date, including month-end and leap-year clamping.
Common tasks
What people use this collection for
- Count or offset a calendar date
Date Difference reports elapsed and inclusive days. Date Calculator adds or subtracts days, weeks, months, or years, clamping month-end and leap days.
- Count working days
Business Days drops Saturday and Sunday. US Federal Holidays 2026 (KE 1.0) is optional and is never assumed.
- Convert or subtract hours
Hours to Decimal turns 7:45 into 7.75. Hours Calculator subtracts two clock times, crosses midnight when needed, and deducts an unpaid break.
Suggested path
From a span to a working week
These links go only to published calculators or stay on this page as unlabeled steps.
Questions
About this collection
Do daylight-saving changes affect calendar results?
No. Calendar tools convert dates to UTC day boundaries. The Hours Calculator uses clock-of-day values and does not model DST springs or falls.
Are holidays excluded automatically?
No. Business Days defaults to weekends only. Choose US Federal Holidays 2026 (KE 1.0) when you want that published list.