Add Days to Date Calculator
Calculate what date it will be after adding days, weeks, months, or years to any starting date. Our free calculator handles month boundaries, leap years, and provides instant results. According to Google Trends, millions of people search for date calculations each month for deadlines, project planning, and personal milestones.
- 30 days = ~1 month (4.3 weeks) | 60 days = ~2 months (8.6 weeks) | 90 days = ~3 months (12.9 weeks)
- 180 days = ~6 months (26 weeks) | 365 days = 1 year (52.1 weeks)
- Common deadlines: 90 days (probation, visas), 30 days (returns), 60 days (notice periods)
- Business days? Use our business days calculator to exclude weekends and holidays
- Going back? Use subtract days calculator to find past dates
Add Time to Date
Enter a date and amount of time to add
Common Date Calculations from Today
Frequently needed future dates calculated from today (-):
| Days | Date | Day | Common Use |
|---|
Days to Weeks and Months Conversion
Use this reference table to quickly convert between days, weeks, and months:
| Days | Weeks | Months (approx) | Common Use |
|---|---|---|---|
| 7 | 1 | 0.23 | Weekly deadline |
| 14 | 2 | 0.46 | Two-week notice |
| 21 | 3 | 0.69 | Three weeks |
| 30 | 4.3 | 1 | Monthly billing, returns |
| 45 | 6.4 | 1.5 | Mortgage rate lock |
| 60 | 8.6 | 2 | Notice period, billing cycle |
| 90 | 12.9 | 3 | Probation, visas, warranties |
| 120 | 17.1 | 4 | Quarterly review |
| 180 | 25.7 | 6 | Half-year, Schengen visa |
| 270 | 38.6 | 9 | Pregnancy term |
| 365 | 52.1 | 12 | Annual renewal, year |
| 730 | 104.3 | 24 | Two years |
Note: Month calculations use average of 30.44 days per month. Actual months vary from 28-31 days.
Month Lengths Reference
When adding days, knowing the number of days in each month helps with planning. Source: TimeandDate.com
| Month | Days | Cumulative (from Jan 1) | Notes |
|---|---|---|---|
| January | 31 | 31 | Start of year |
| February | 28/29 | 59/60 | 29 in leap years |
| March | 31 | 90/91 | ~3 months from Jan 1 |
| April | 30 | 120/121 | Spring |
| May | 31 | 151/152 | - |
| June | 30 | 181/182 | ~6 months / mid-year |
| July | 31 | 212/213 | - |
| August | 31 | 243/244 | - |
| September | 30 | 273/274 | ~9 months |
| October | 31 | 304/305 | - |
| November | 30 | 334/335 | - |
| December | 31 | 365/366 | End of year |
- A year is a leap year if divisible by 4, except century years (1900, 2100) which must be divisible by 400
- Leap years: 2024, 2028, 2032, 2036...
- Not leap years: 2025, 2026, 2027, 2100
How to Add Days to a Date
Adding days to a date is straightforward, but month boundaries and leap years can make manual calculation tricky. Here's how our calculator works:
The Formula
- Start with your base date - Any valid calendar date
- Add the specified amount - Days, weeks, months, or years
- Adjust for month lengths - February has 28-29 days, months vary 28-31
- Account for leap years - February 29 exists only in leap years
Adding Months vs Adding Days
There's an important distinction:
- Adding "30 days" always adds exactly 30 calendar days
- Adding "1 month" moves to the same day number in the next month (Jan 15 + 1 month = Feb 15)
- If the target day doesn't exist (like February 30), it adjusts to the last valid day (February 28 or 29)
Example: Adding 90 Days to January 15, 2026
January 15 + 90 days:
- January has 31 days, so 16 days remain (Jan 16-31)
- February 2026 has 28 days (not a leap year)
- 90 - 16 - 28 = 46 days into March
- But March only has 31 days, so we continue to April
- 46 - 31 = 15 days into April
- Result: April 15, 2026
Calendar Days vs Business Days
This calculator adds calendar days (all days including weekends). For work deadlines, you may need business days:
| Calendar Days | Business Days | Total Weeks |
|---|---|---|
| 7 | 5 | 1 |
| 14 | 10 | 2 |
| 30 | ~22 | ~4.3 |
| 60 | ~43 | ~8.6 |
| 90 | ~64 | ~12.9 |
| 180 | ~129 | ~25.7 |
| 365 | ~251 | ~52.1 |
Business day calculations are important for:
- Shipping estimates - "5-7 business days" means ~7-10 calendar days
- Payment terms - Net 30 may mean 30 business or calendar days (check contract)
- Legal deadlines - Courts often use business days for filing deadlines
- Banking - Federal Reserve and banks use business days for ACH transfers
Frequently Asked Questions
Use the calculator above or visit our dedicated 90 days from today page for an instant answer. 90 days is commonly used for probation periods, visa validity, return policies, and IRS deadlines.
Select "Weeks" from the unit dropdown and enter 6. Alternatively, enter 42 days (6 x 7 = 42). Both methods give the same result. Our calculator handles either approach.
No. Adding "1 month" moves to the same day number in the next month. January 15 + 1 month = February 15 (31 days). January 31 + 1 month = February 28/29 (28-29 days) since February 31 doesn't exist.
Use our Business Days Calculator to add only working days (Monday-Friday), excluding weekends and optionally US federal holidays.
Click the "30 days" quick button above for an instant answer. 30 days is approximately 4.3 weeks or about 1 month, commonly used for return policies, billing cycles, and short-term deadlines.
Use our Days Until calculator to count days until any future date. For past dates, use the Days Since calculator. The main Date Calculator can do both.
Yes. Our calculator automatically handles leap years. February 29 is included when calculating across leap year dates. For example, adding 30 days to February 1, 2024 (leap year) lands on March 2, 2024.
Calendar days include all days (weekends and holidays). Business days only count Monday-Friday, excluding holidays. 30 calendar days equals approximately 22 business days. See our business days guide for details.
This calculator is designed for adding days forward. To calculate past dates, use our Subtract Days calculator, which is optimized for backward calculations.
Click the "6 months" quick button for an instant answer. 180 days is exactly 6 months or about 26 weeks, commonly used for Schengen visa calculations (90/180 rule) and mid-year planning.