Days Between Dates
Calculate the exact number of days between any two dates
Frequently Asked Questions
Enter your start date and end date in the calculator, then click Calculate. The tool shows the exact number of days between them, along with weeks, approximate months, and total hours. You can toggle whether to include the end date in the count.
Inclusive counting counts both the start and end dates (e.g., Monday to Wednesday = 3 days). Exclusive counting counts only the days between them (Monday to Wednesday = 2 days). Our calculator lets you choose with the "Include end date" checkbox.
Yes. The calculator uses actual calendar dates, so it automatically accounts for leap years (366 days) and varying month lengths. February 1 to March 1 will correctly return 28 or 29 days depending on the year.
Days Between Dates Calculator: The Complete Guide to Counting Days
Counting the days between two dates is one of the most common date calculations people need—and one of the trickiest to do accurately by hand. Months have 28, 29, 30, or 31 days, leap years add an extra day every four years (with exceptions), and the difference between inclusive and exclusive counting can change your result by a full day. Our Days Between Dates calculator handles all of this automatically, giving you an accurate count in seconds along with conversions to weeks, months, and hours.
Inclusive vs. Exclusive Counting
The most common source of confusion in day counting is whether to include the start date, the end date, both, or neither. Different contexts use different conventions:
Exclusive Counting: Days Between = End Date − Start Date. Example: January 1 to January 10 = 9 days. This counts the "gaps" between dates and is the default in most programming languages and spreadsheets.
Inclusive Counting: Days Between = (End Date − Start Date) + 1. Example: January 1 to January 10 = 10 days. This counts both the first and last day and is common in legal, rental, and medical contexts.
Inclusive Counting: Days Between = (End Date − Start Date) + 1. Example: January 1 to January 10 = 10 days. This counts both the first and last day and is common in legal, rental, and medical contexts.
Our calculator defaults to inclusive counting (the "Include end date" checkbox is checked), but you can uncheck it for exclusive counting. Always verify which convention applies to your situation—a one-day difference can matter for legal deadlines, insurance claims, or contract terms.
Worked Examples
Example 1 — Rental Period: You sign a lease starting March 1 and ending August 31. Inclusive count: 184 days (March: 31, April: 30, May: 31, June: 30, July: 31, August: 31). Exclusive count: 183 days. Most lease agreements count inclusively, meaning you pay rent for the full period including both the move-in and move-out dates.
Example 2 — Countdown to an Event: Today is January 15 and your wedding is on June 20. Exclusive count (days remaining): 156 days. This is the natural "countdown" number—you have 156 more days to prepare. An inclusive count would be 157, counting today itself.
Example 3 — Pregnancy Due Date: A pregnancy is typically 280 days from the first day of the last menstrual period (LMP). If LMP is April 10, adding 280 days (exclusive of the start) gives a due date of January 15 of the following year. Obstetricians use this standard 280-day (40-week) calculation.
Common Date Spans: Quick Reference
| Period | Calendar Days | Common Use |
|---|---|---|
| 1 week | 7 | Weekly deadlines, follow-ups |
| 2 weeks | 14 | Pay periods, notice periods |
| 30 days | 30 | Return policies, billing cycles, trial periods |
| 45 days | 45 | Mortgage contingencies, escrow |
| 60 days | 60 | COBRA enrollment, insurance windows |
| 90 days | 90 | Probation periods, quarterly reviews, visa stays |
| 120 days | 120 | Construction milestones, warranty claims |
| 180 days | 180 | Half-year reviews, statute of limitations |
| 365 days | 365 | Annual renewals, subscriptions, warranties |
| Pregnancy | 280 | Due date from last menstrual period |
| School year (US) | ~180 | Instructional days, K-12 |
Legal Day Counting Rules
Legal deadlines have strict rules about how days are counted, and getting it wrong can forfeit your rights:
- Federal courts (FRCP Rule 6): When a deadline is stated in days, exclude the day of the triggering event and include the last day. If the last day falls on a weekend or legal holiday, the deadline extends to the next business day. For periods less than 11 days, weekends and holidays within the period are also excluded.
- Statutes of limitations: These typically use calendar days and start the day after the triggering event. A 2-year statute starting from an injury on March 15, 2024 expires on March 15, 2026—but if that falls on a weekend, many jurisdictions extend to the next Monday.
- Contract notice periods: "30 days' notice" usually means 30 calendar days from the date notice is given (exclusive of the notice day itself). Some contracts specify "30 business days," which is significantly longer—about 6 weeks.
- Tax deadlines: The IRS uses calendar days. If a filing deadline falls on a weekend or holiday, it moves to the next business day. The April 15 tax deadline, for instance, shifts to April 17 or 18 when the 15th falls on a weekend.
Legal Disclaimer: Day-counting conventions vary by jurisdiction, court, and contract type. This calculator provides calendar day counts only. For legal deadlines, always consult the specific rules that apply to your case and verify with legal counsel.
Days Between Dates in Different Contexts
- Travel planning: Knowing the exact number of nights (exclusive count) vs. days (inclusive count) matters for hotel bookings. Checking in on Monday and checking out on Friday is 4 nights but covers 5 calendar days.
- Project management: Gantt charts and project timelines count working days or calendar days depending on the methodology. A "30-day project" in calendar days is about 22 business days.
- Medical and health: Prescription durations, quarantine periods, and recovery timelines all use day counts. A "14-day quarantine" starting Monday means you're cleared the Monday after next (day 15).
- Financial calculations: Interest accrual, loan terms, and investment holding periods all depend on precise day counts. Bond markets use conventions like "Actual/360" or "30/360" for interest calculations, which can produce different day counts than the calendar.
- Education: School years typically require 180 instructional days. Snow days, holidays, and professional development days all factor into whether a district meets this threshold.
Counting Tip: When counting days on a calendar, the most common mistake is counting the start date. If someone says "call me in 3 days" on Monday, they usually mean Thursday (3 days later), not Wednesday. Our exclusive mode handles this naturally—uncheck "Include end date" for countdown-style calculations.
Our Days Between Dates calculator is free, runs entirely in your browser, and stores no data. For related tools, try our Date Difference Calculator, Business Days Calculator, Add/Subtract Days, and Age Calculator.