Calculate the exact number of days, weeks, months, and business working days between any two calendar dates.
Select the starting calendar date from the date picker.
Select the concluding calendar date.
Toggle the checkbox if you want to include the concluding day in the total count.
Instantly view total days, weeks + days, full months, and business working days.
Total Days = (End Date in ms − Start Date in ms) ÷ (1000 × 60 × 60 × 24) End Date in ms = Millisecond timestamp of ending date1000 × 60 × 60 × 24 = 86,400,000 milliseconds per standard calendar dayWeeks = floor(Days ÷ 7) | Remainder Days = Days mod 7 Days = Total elapsed calendar days7 = Seven days in a standard weekStep-by-step breakdown of common real-world time scenarios, work shifts, and duration math.
Comparing calendar days in October.
Oct 1, 2026 to Oct 31, 2026 (30 elapsed days) Planning summer break duration.
Jun 15, 2026 to Aug 20, 2026 (66 elapsed days) Tracking a full 365-day annual cycle.
Jan 1, 2026 to Jan 1, 2027 (365 elapsed days) Calculating the interval between two calendar dates is a daily task in contract agreements, rental leases, project milestone tracking, and visa stay limits. If you also need specific clock hour, minute, and second calculations, use our Date & Time Calculator.
By convention, subtraction between two dates (e.g. May 1 to May 2) yields 1 day (exclusive of the end date). If a project spans from the beginning of May 1 to the end of May 2, toggle the "Include end date" option to count both days (2 full days). For intra-day clock duration, test our flagship Time Duration Calculator.
Subtract the start date from the end date in milliseconds, and divide the result by 86,400,000 (the number of milliseconds in one 24-hour day).
Yes. The calculator includes a business days filter that counts only Monday through Friday while excluding weekend days.
All calculations on this tool are deterministic and rigorously tested against base-60 modulo arithmetic and US Fair Labor Standards Act (FLSA 29 CFR § 785.48) payroll rounding guidelines.