The Date Calculator is a versatile tool designed to solve everyday chronological math problems. Working with dates can be notoriously tricky due to leap years, varying month lengths, and timezones. This tool handles the complex calendar logic for you.

Common Use Cases

Project Planning: Find exact delivery dates by adding weeks or business days to a start date.
Age & Anniversaries: Calculate exactly how old something is down to the days, or how many days are left until a special event.
Legal & Finance: Determine expiration dates for contracts, warranties, and financial grace periods.

Leap Years & Calendar Rules

Our calculator automatically accounts for leap years. A leap year occurs every 4 years, adding a 29th day to February. However, years divisible by 100 are not leap years unless they are also divisible by 400 (e.g., the year 2000 was a leap year, but 1900 was not).

Standard Year365 Days

Leap Year366 Days

Standard Month28, 29, 30, or 31 Days

Timezone Context: Date calculations are performed using your browser's local timezone to ensure days roll over exactly when you expect them to in your locale.

How the calculation works

Adding days moves the calendar forward, including month lengths and leap days.

New date = start date + number of days

2024 and 2028 are leap years. February 2026 has 28 days.

Worked example: 90 days after 1 January 2026

January contributes 30 days after the 1st, leaving 60.
February 2026 has 28 days, leaving 32.
1 April is day 32 of the remainder, so 90 days after 1 January is 1 April 2026.

Days after 1 January 2026

Days	Date
30	31 Jan 2026
90	1 Apr 2026
365	1 Jan 2027

Frequently asked questions

What date is 90 days after 1 January 2026?▼

1 April 2026.

What date is 365 days after 1 January 2026?▼

1 January 2027. 2026 is not a leap year.

How do you count the days between two dates?▼

Subtract the dates. From 1 January to 1 April 2026 is 90 days.