📅 Date Difference Calculator

Contracts and legal deadlines hinge on whether a period is counted in calendar days (every day, including weekends and holidays) or business days (typically Monday–Friday, excluding public holidays).

In real estate, an inspection contingency of “10 business days” can run several days longer on the calendar than “10 calendar days,” especially across a holiday week. The same applies to notice periods, cure periods, and payment terms in business milestones. Always read whether an agreement specifies calendar or business days, and confirm how the jurisdiction treats a deadline that lands on a weekend or holiday — it often rolls to the next business day.

A leap year adds February 29 every four years (skipping century years not divisible by 400), which affects any duration that spans it. In finance, the number of days assumed in a year is defined by a day-count convention:

• Actual/360: counts the actual days elapsed but divides by a 360-day year. Common in commercial loans and money-market instruments — it slightly increases the effective interest charged.
• Actual/365 (Actual/Actual): counts actual days over a 365-day (or 366 in a leap year) basis. Common for many consumer loans and bonds.

Because these conventions differ, the same nominal rate can produce different interest depending on which is used — so always confirm the convention when comparing loan or investment terms.