Add or Subtract Days Calculator

Calculate future or past dates with precision. Our enterprise-quality date calculator helps you add or subtract days from any date, with support for business days, detailed breakdowns, and multiple format outputs.

Select the date to calculate from
Choose to add or subtract days
Enter between 1 and 10,000 days

How to Use the Date Calculator

  1. Select your start date - Click the date picker or type the date manually in the format shown (mm/dd/yyyy).
  2. Choose your method - Select "Add Days" to calculate a future date, or "Subtract Days" for a past date.
  3. Enter the number of days - Type any number between 1 and 10,000 days.
  4. (Optional) Enable business days - Check the box to exclude weekends from your calculation, perfect for project deadlines.
  5. Click Calculate - Get instant, detailed results with multiple date formats and a comprehensive breakdown.

Back to Calculator

When to Use This Date Calculator

Business & Project Management

Calculate project deadlines: If your project timeline is 45 business days, simply enter today's date, add 45 days, and enable "Business Days Only" to get your exact deadline excluding weekends.

Invoice due dates: Create accurate invoices with Net 15, Net 30, or Net 45 payment terms. Enter your invoice date and add the appropriate number of days to determine the exact due date.

Contract milestones: Track important contract dates, renewal periods, and milestone deadlines with precision. Calculate 90-day notice periods, 180-day reviews, or annual renewal dates instantly.

Personal Planning

Subscription tracking: Know exactly when your free trials, memberships, or subscriptions expire. Enter the start date and add the trial period (7, 14, or 30 days) to get the expiration date.

Event planning: Planning a wedding, party, or vacation? Calculate 60 days before for invitations, 30 days before for RSVPs, or any custom timeframe you need.

Fitness goals: Track your 30-day, 60-day, or 90-day fitness challenges. Enter your start date and see exactly when you'll reach your goal.

Legal & Compliance

Legal deadlines: Calculate filing deadlines, statute of limitations dates, and response periods with confidence. The business days option ensures accurate business-day calculations for legal requirements.

Notice periods: Determine exact dates for employment notice periods, lease terminations, or contract cancellations.

Healthcare & Medical

Medication schedules: Calculate when to refill prescriptions or complete treatment courses. If your prescription is for 30 days, add 30 days to see your refill date.

Appointment planning: Schedule follow-up appointments precisely (e.g., "return in 6 weeks" = add 42 days).

Key Features

  • Add or subtract up to 10,000 days
  • Business days calculation (excludes weekends)
  • Multiple date format outputs (Long, Short, ISO 8601)
  • Detailed breakdown (weeks, business days, weekends)
  • Auto-scroll to results for easy viewing
  • Copy to clipboard functionality
  • Quick preset calculations (30, 60, 90, 120, 180, 365 days)
  • Mobile-responsive design

Frequently Asked Questions

How do I add days to a date?
Enter your start date, select "Add" as the method, enter the number of days you want to add, and click Calculate. The calculator will instantly show you the resulting date with a detailed breakdown.
Can I calculate business days only?
Yes! Check the "Business Days Only" option to exclude weekends from your calculation. This is perfect for project planning, invoice terms, and deadline tracking in professional settings.
What is the maximum number of days I can add or subtract?
You can add or subtract up to 10,000 days (approximately 27 years) from any date. This range covers virtually all practical use cases for date calculations.
Does this calculator account for leap years?
Yes, the calculator automatically accounts for leap years, ensuring accurate date calculations across all years, including February 29th in leap years.
Can I use this calculator for contract dates?
Absolutely! This calculator is perfect for determining contract end dates, renewal dates, notice periods, and payment terms. Use the business days option for terms like "Net 30 business days."
What date formats are supported?
The calculator provides results in multiple formats: long format (e.g., "Monday, January 15, 2024"), short format (e.g., "January 15, 2024"), and ISO 8601 format (e.g., "2024-01-15") for technical use.

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