Week 53 is the 53rd ISO week, occurring in years where 1 January or 31 December falls on a Thursday. The frequency is approximately every 5 to 6 years.
When week 53 occurs
Recent and upcoming 53-week ISO years include:
- 2015
- 2020
- 2026
- 2032
- 2037
- 2043
- 2048
The rule follows from the First-Thursday Rule. A 53-week year arises when a 365-day year starts on Thursday or a 366-day leap year starts on Wednesday or Thursday, per ISO 8601.
Common pitfalls
Week 53 causes 3 recurring problems in business systems:
- Payroll — weekly pay cycles produce 53 pay periods that year, breaking annualised salary calculations that assume 52.
- Fiscal reporting — year-on-year comparisons distort when one period has 53 weeks and the prior has 52.
- Retail calendars — 4-4-5 and 4-5-4 calendars add a 53rd week as a separate "stub" period, requiring manual reconciliation.
Australian employers running weekly payroll should confirm software handles the 53rd week without prorating the annual salary across an extra period.