A printable week-date tool for ISO week numbers, Monday-start planning, 52 or 53 week-years, and date conversion beside the CalculationTime clockface.
Inputs, result, proof and time.
Use the instrument above, then check the calculation record, assumptions and related tools below.
Week Builder
Build a printable ISO week
CalculationTime ISO Week Calendar
2026-W36
Monday 31 August 2026 to Sunday 06 September 2026
Week-Year
2026
Weeks In Year
53
Business Days
5
Boundary
Month
Selected dateSunday 06 September 2026
ISO week date2026-W36-7
ISO weekdaySunday
Mon31
31 Aug 2026
ISO Day
1
Year Day
243
Tue1
01 Sept 2026
ISO Day
2
Year Day
244
Wed2
02 Sept 2026
ISO Day
3
Year Day
245
Thu3
03 Sept 2026
ISO Day
4
Year Day
246
Fri4
04 Sept 2026
ISO Day
5
Year Day
247
Sat5
05 Sept 2026
ISO Day
6
Year Day
248
Sun6
06 Sept 2026
ISO Day
7
Year Day
249
Week-Year Window
ISO 2026 starts Monday 2025-12-29 and the next ISO week-year starts Monday 2027-01-04.
Notes
Sprint goals, release windows, roster notes, deadlines and review checkpoints.
Assumptions
ISO 8601 Monday-start weeks, local browser Gregorian dates, selected sheet range 2026-08-31 to 2026-09-06.
ISO Output Room
Keep week numbers printable, traceable and boundary-aware
The tabs collect the week-date calculation, browser print path, planning limits and standards notes so the page can be checked instead of merely trusted.
Week-date construction
The planner builds each week from ISO week 1 Monday
CalculationTime finds the Monday of ISO week 1 from the January 4 anchor, then adds whole weeks to draw the selected Monday to Sunday sheet.
The selected week-year automatically clamps to 52 or 53 valid ISO weeks.
Date conversion updates the sheet so January and December boundary dates are easy to inspect.
Weekend, ordinal day and neighbouring week-year markers stay visible in the printable report.
ISO year + week number -> week 1 Monday -> selected Monday-Sunday sheet -> date conversion
Method
ISO weeks are built from the Thursday rule
ISO week 1 is the week containing the year's first Thursday. The calculator finds the Monday of week 1 from January 4, then adds whole weeks to build the selected Monday to Sunday sheet. Date conversion uses the same Thursday anchor so early January and late December dates can belong to the neighbouring ISO week-year.
Week-year range
The planner accepts ISO week-years from 1900 through 2100 and automatically limits the week number to 52 or 53.
Print path
The print button opens browser print and the print stylesheet keeps the week sheet, converted date result, notes and assumptions.
Limits
This page does not infer public holidays, fiscal calendars, payroll periods or regional work rules. It only calculates ISO week-date structure.
Source Notes
Standards and platform basis
The page labels week numbers using the ISO 8601 week-date convention: weeks start on Monday, and week 1 is the week containing the first Thursday of the Gregorian year. Browser JavaScript Date objects provide the underlying Gregorian date arithmetic.