Count down the number of days from a starting date to a target date.
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Days until is target date minus starting date, in calendar days. January 1 to January 10 gives 9 days; a target before the starting date gives a negative result. Equal dates give zero.
Formula · Worked example · Units and assumptions · Questions and answers
Days until = (Target date − Start date) ÷ 86,400,000 msFrom January 1 to January 10, there are 9 elapsed days.
Expecting both endpoints to count as full days, or interpreting a negative result as an error instead of a past target.
Explanations updated . See the calculation methodology for precision and review details.
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Result: 9 days
A positive nine-day result means the target is nine calendar days after the chosen starting date. It is not a business-day deadline calculation.
Result: -9 days
Reversing those dates gives minus nine, indicating that the target has passed. A negative result is meaningful, not a failed calculation.
Worked decisions, assumptions, and checks that put the tools in context. Guides are currently published in English.
Choose between elapsed days, inclusive calendar dates, signed countdowns, and completed age with leap-year examples and clearly defined calendar rules.
Read the guide →A negative number means the target date occurred before the selected starting date.
The result measures elapsed date boundaries; a target of tomorrow returns one day.
Yes. Enter any valid starting date in the optional Count from field.