Date Calculator - D - Day, Days Between Dates, Workdays

Runs entirely in your browser. No data is uploaded.

When you’re planning timelines (projects, contracts, exams) you often need an exact day count, not a rough estimate. Quickly calculate D - Day, date differences, and workdays so you can communicate schedules with confidence.

Calculate D - Day, days between two dates, workdays (exclude weekends), and contract periods instantly. Runs in your browser (no uploads).

Show detailed guide & explanations▼

Why you may need this tool

Date calculations often look simple until rules appear: whether the end date is inclusive, whether weekends should be excluded, or how to interpret “N days after” for deadlines. Small mistakes can lead to incorrect guidance, missed schedules, and confusing communication. A date calculator helps you apply consistent rules and get repeatable results for planning, submissions, and time - based workflows.

How to use

Choose start and end dates (or an offset), set relevant options, and use the result as the basis for planning and communication.

Pick start and end dates
Choose what to calculate (D - Day, difference, workdays, contract period)
Adjust options (include end date, exclude weekends)
Copy results

Examples

Calculating project duration between two dates

Duration depends on whether you count the end date and whether weekends matter. A calculator helps you apply the same rule consistently when communicating timelines.

Planning backwards from a deadline

Deadlines often drive work plans. By computing remaining days and offsets, you can build a realistic checklist and avoid underestimating preparation time.

Benefits & differentiators

Consistent calculations reduce misunderstandings and prevent last - minute corrections. When you compare multiple candidate schedules, quick recalculation helps you choose a feasible timeline. For teams, having a clear computed result makes it easier to align on deadlines and avoid ambiguity around “how many days remain” and what counts as a working day.

Who this is for

Recommended if you: - manage deadlines and need consistent date differences - plan work based on remaining days or offsets - communicate timelines across a team - want to reduce mistakes around inclusive/exclusive counting