Does this include weekends?

This tool calculates calendar days, meaning it includes weekends and holidays. If you add 10 days to a Friday, it will simply count 10 days forward on the calendar.

How does it handle leap years?

The calculator is fully leap-year aware. If you add 1 year to February 29th, 2024, it will correctly land on February 28th, 2025 (since 2025 is not a leap year).

Can I calculate business days?

Currently, this tool calculates total calendar days. We are working on a separate 'Business Days Calculator' to exclude weekends and public holidays.

What is the 90-day rule?

Many legal and visa documents refer to a '90-day period'. This is often different from '3 months'. Use this tool to calculate exactly 90 days, which is more precise than counting months.

Is the calculation accurate?

Yes. It uses the standard Gregorian calendar rules built into modern browsers, ensuring 100% accuracy for any date from year 100 to 9999.

Add or Subtract Time

Find out exactly what date it will be in X days, or what date it was Y months ago.

Start Date

Years

Months

Days

Result Date

Enter a start date to see the result

Why Use a Date Calculator?

Calculating dates in your head is surprisingly difficult. "30 days from today" isn't just "next month" because months have different lengths (28, 30, or 31 days). Leap years add another layer of complexity.

Our Add/Subtract Date Calculator eliminates the guesswork. It's an essential tool for professionals and planners who need precision.

Common Use Cases

⚖️ Legal & Visas

The 90/180 Rule: Many tourist visas allow you to stay for 90 days. Overstaying by even one day can cause huge problems. Use this tool to find your exact "must leave by" date.

🤰 Pregnancy & Health

Due Dates: Pregnancy is calculated as 280 days (40 weeks) from the last period. Add 280 days to find the estimated due date.

📦 Warranties & Returns

Expiration: If you bought a laptop on Jan 15th with a 90-day return policy, when is the last day you can return it? (Hint: It's not April 15th).

📅 Project Management

Sprints: If a project sprint is 2 weeks long and starts on Wednesday, what is the exact completion date?

Days vs. Months: The Big Confusion

In casual conversation, we often use "one month" and "30 days" interchangeably. In date calculation, they are very different:

Add 1 Month: Jan 31 + 1 Month = Feb 28 (or 29). The day is clamped to the end of the month.
Add 30 Days: Jan 31 + 30 Days = March 2 (or March 1 in leap years).

Pro Tip: For legal contracts and deadlines, always check if the document specifies "days" or "months". "90 days" is almost never exactly "3 months".

Frequently Asked Questions

What happens if I subtract time? ▼

Subtracting works exactly like adding, but backwards in time. This is useful for finding past dates, like "What was the date 180 days ago?" (often used for calculating residency periods).

Does it account for Daylight Saving Time? ▼

Since this tool calculates dates (calendar days), Daylight Saving Time (which affects hours) does not impact the result. A day is counted as a day regardless of whether it had 23, 24, or 25 hours due to a clock change.

Can I add weeks? ▼

Yes! Adding 1 week is exactly the same as adding 7 days. Our tool allows you to input weeks directly for convenience.

Is my data private? ▼

Absolutely. All calculations happen instantly in your browser using JavaScript. We do not track the dates you enter or send them to any server.