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Calculate Days Between Two Dates in Java

beginner· Date & Time · Date & Time

Problem

The difference between two dates can be measured as a single unit (a total number of days) or as a calendar period (months plus leftover days).

Find how many days and whole weeks lie between 15 January 2026 and 11 October 2026.

Input

2026-01-15, 2026-10-11

Output

269 days, 38 weeks

Java Program

Java

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

public class DaysBetweenDates {
    public static void main(String[] args) {
        LocalDate start = LocalDate.of(2026, 1, 15);
        LocalDate end = LocalDate.of(2026, 10, 11);

        long days = ChronoUnit.DAYS.between(start, end);    // end is exclusive
        long weeks = ChronoUnit.WEEKS.between(start, end);  // whole weeks only
        long backwards = ChronoUnit.DAYS.between(end, start);

        System.out.println("Days between:  " + days);
        System.out.println("Whole weeks:   " + weeks);
        System.out.println("Reversed args: " + backwards);
    }
}

▶ Run Code

Output

Days between:  269
Whole weeks:   38
Reversed args: -269

Core Logic

ChronoUnit.DAYS.between(start, end) counts the days from start up to, but not including, end.

How It Works

1LocalDate.of creates the two fixed dates.
2ChronoUnit.DAYS.between returns the total day count as a long.
3ChronoUnit.WEEKS.between counts only complete weeks.
4Swapping the arguments returns the same distance with a negative sign.

269 days is 38 weeks and 3 days, so the whole-week count is 38.

💡

Key Point: The end date is exclusive — DAYS.between(d, d.plusDays(1)) is 1, not 2; add one yourself if you need to count both endpoints, as in hotel or leave calculations.

Key Concepts

ChronoUnit.DAYS.between()ChronoUnit.WEEKSLocalDate.of()

Approach 2: Using Period.between()

Java

import java.time.LocalDate;
import java.time.Period;

public class DaysBetweenPeriod {
    public static void main(String[] args) {
        LocalDate start = LocalDate.of(2026, 1, 15);
        LocalDate end = LocalDate.of(2026, 10, 11);

        Period gap = Period.between(start, end); // calendar-aware: years, months and leftover days
        System.out.println(gap.getMonths() + " months and " + gap.getDays() + " days");
        System.out.println("ISO form: " + gap);
    }
}