90-Day Probation Period Calculator

You've just hired someone with a 90-day probation period. But when exactly does it end? The answer depends on whether your company counts in calendar days or business days — and the difference is significant.

Calendar Days vs Business Days: The Impact

For an employee starting on January 5, 2026:

• 90 calendar days = April 5, 2026 (about 3 months)
• 90 business days = May 15, 2026 (about 4.5 months)

That's a 6-week difference. Getting this wrong can create legal issues around benefits eligibility, termination rights, and performance review timing.

Which Standard Do Most Companies Use?

The majority of employers use calendar days for probation periods. This is the most common approach in:

• The United States (most states)
• United Kingdom
• Australia
• Canada

However, some organizations — particularly government agencies and unionized workplaces — specify business days. Always check your employment contract or company handbook.

Common Probation Period Lengths

• 30 days — Common for hourly/temporary positions
• 60 days — Used by some mid-size companies
• 90 days — The most common standard in the US, UK, and Australia
• 6 months — Common in Europe, especially for senior roles

What Happens During Probation?

During a probation period, employers typically have more flexibility to terminate employment. After probation ends:

• Full employment protections kick in
• Benefits like health insurance may become active
• Notice period requirements may change
• Performance reviews become part of the formal record

Tips for HR Professionals

1. Document the exact counting method in your offer letter — "90 calendar days" or "90 business days"
2. Set calendar reminders for the 60-day and 80-day marks to begin the review process
3. Account for holidays — a probation period over December will have fewer working days for evaluation
4. Use a calculator — don't count manually. Calculate the exact end date here.