How to Calculate Business Days for Project Deadlines (Free Calculator)

Business days (also called working days or weekdays):

Monday through Friday, excluding public holidays.

Not business days:

• Saturdays

• Sundays

• Federal/national holidays

• Company-specific holidays (varies by organization)

Example:

If today is Friday, Jan 12:

• "1 business day from now" = Monday, Jan 15 (skips weekend)

• "5 business days from now" = Friday, Jan 19

• "10 business days from now" = Thursday, Jan 25

Important:

Business days ≠ weekdays when holidays involved.

Weekdays = Mon-Fri (including holidays)

Business days = Mon-Fri (excluding holidays)

Different definitions exist:

Financial industry:

"Banking business days" exclude bank holidays (different from federal holidays in some countries).

International business:

Business days vary by country:

• US/Canada/Europe: Mon-Fri

• Middle East: Sun-Thu (some countries)

• Israel: Sun-Fri (Saturday is Sabbath)

Contracts:

Always specify: "U.S. business days" or "business days as recognized in [location]."

Custom definitions:

Some companies:

• Include Saturdays (6-day work week)

• Exclude specific cultural holidays

• Define "business hours" (8am-5pm same day ≠ 1 business day)

For calculations within same week:

Example: 3 business days from Tuesday, Jan 9

1. Start: Tuesday (count as day 0 or day 1 depending on "from" vs "after" interpretation)

2. Add 3 days: Wed (+1), Thu (+2), Fri (+3)

3. Result: Friday, Jan 12

For calculations crossing weekends:

Example: 5 business days from Thursday, Jan 11

1. Thursday → Friday = 1 day (Jan 12)

2. Skip weekend (Sat-Sun don't count)

3. Monday → Tuesday → Wednesday = 3 more days (Jan 15, 16, 17)

4. Total: 5 business days

5. Result: Wednesday, Jan 17

Quick rule:

Every 5 business days = 1 full work week

Every 10 business days = 2 work weeks

Every 20 business days = 1 calendar month (approximately)

For large business day counts:

Example: 30 business days from Monday, Jan 8

1. Divide by 5: 30 ÷ 5 = 6 weeks

2. Add 6 weeks to start date: Jan 8 + 42 days = Feb 19

3. Adjust for partial weeks (0 extra days in this case)

4. Result: Monday, Feb 19

With remainder:

Example: 23 business days from Wednesday, Jan 10

1. Divide: 23 ÷ 5 = 4 weeks + 3 days

2. Add 4 weeks: Jan 10 + 28 days = Feb 7 (Wednesday)

3. Add 3 more business days: Thu (+1), Fri (+2), Mon (+3, skip weekend)

4. Result: Monday, Feb 12

When holidays fall on business days:

Example: 10 business days from Monday, Jan 15, 2025

(Martin Luther King Jr. Day is Jan 15—a federal holiday)

Calculation:

1. MLK Day (Mon Jan 15): Not a business day

2. Start counting from Tuesday, Jan 16

3. Add 10 business days:

- Week 1 (Jan 16-19): Tue-Fri = 4 days

- Weekend (skip)

- Week 2 (Jan 22-26): Mon-Fri = 5 days

- Week 3 (Jan 29): Mon = 1 day

4. Result: Monday, Jan 29

Key rule:

For each holiday that falls on a weekday within your calculation period, add 1 day to the end result.

1. Visit our Free Business Days Calculator

2. Enter start date

3. Choose calculation type:

• Add business days: Find end date (e.g., 10 business days from today)

• Calculate difference: Count business days between two dates

4. Optional: Select country for automatic holiday recognition

5. Click "Calculate"

6. Get result with breakdown

What it shows:

• End date (for "add" mode)

• Number of business days (for "difference" mode)

• Weekends skipped

• Holidays excluded (if country selected)

• Visual calendar (optional)

Accuracy guarantee:

✓ Correctly handles weekend boundaries

✓ Accounts for holidays (if selected)

✓ Handles year transitions

✓ Validates leap years

✓ Shows step-by-step breakdown

Project management:

"Project must be completed in 20 business days."

→ Enter start date, add 20 business days, get deadline

Contract terms:

"Payment due 30 business days after invoice date."

→ Enter invoice date, add 30 business days, get payment deadline

SLA compliance:

"Support tickets resolved within 3 business days."

→ Enter ticket date, add 3 business days, get resolution deadline

Delivery estimates:

"Ships in 5-7 business days."

→ Calculate both 5 and 7 business days for delivery window

Legal deadlines:

"Response required within 10 business days of receipt."

→ Critical for compliance, use calculator to verify

Retroactive calculations:

"How many business days between Jan 1 and Feb 1?"

→ Use "calculate difference" mode

Question: If deadline is "5 business days from Saturday, Jan 13," when is the due date?

Two interpretations:

Interpretation 1 (Most common):

Saturday doesn't count as business day

Start counting Monday, Jan 15

5 business days from Monday = Friday, Jan 19

Interpretation 2 (Literal):

"From Saturday" means Saturday is day zero

Start counting Monday (first business day after Saturday)

5 business days = Friday, Jan 19

Result: Same answer, but clarify in contracts.

Best practice:

Always specify: "5 business days from the next business day following [date]" for clarity.

Question: 3 business days from Monday, Jan 15 (MLK Day holiday)

Two interpretations:

Option A (Count from next business day):

MLK Day doesn't count

First business day = Tuesday, Jan 16

3 business days = Thursday, Jan 18

Option B (Holiday shifts calculation):

Start from Monday, but Monday doesn't count

Add 1 to account for holiday

3 business days = Friday, Jan 19

Legal/contract standard:

Usually Option A (start from next available business day)

Our calculator:

Uses Option A by default (most common interpretation)

Question: Is "same day" a business day?

Scenario: Request submitted Monday 9am, SLA is "1 business day response."

Option 1 (Next business day):

1 business day from Monday = Tuesday

Response due Tuesday EOD

Option 2 (Same day if hours remain):

If submitted before cutoff (e.g., 2pm)

1 business day = same day (Monday EOD)

Best practice:

Define business day as:

• "Next business day" (explicit)

• "Within 24 business hours" (hour-based, not day-based)

• "By end of next business day" (clearest)

Problem:

Contract signed Monday 11pm EST, client in Tokyo (Tuesday 12pm JST)

"5 business days from signing"

Which date is Day 0?

• In New York: Monday

• In Tokyo: Tuesday (13 hours ahead)

Solution:

Always specify timezone in contracts:

"5 business days from [date] at 11:59pm EST"

Our calculator:

Uses your local timezone unless specified otherwise

Clear deadline clauses:

Good:

"Payment due 30 business days from invoice date, where business days are Monday-Friday excluding U.S. federal holidays."

Better:

"Payment due within 30 business days of invoice date. Business days are defined as Monday through Friday, 9am-5pm Eastern Time, excluding U.S. federal holidays as recognized by the Federal Reserve."

Best:

"Payment due by [specific date: February 28, 2026], which is 30 business days from the invoice date of January 15, 2026."

Why specific dates matter:

Eliminates ambiguity

No calculation disputes

Easy to enforce

Combined approach:

"Payment due 30 business days from invoice date (estimated: February 28, 2026). Business days defined as Monday-Friday excluding U.S. federal holidays."

Ambiguous language to avoid:

❌ "Within 10 days" (business or calendar?)

✓ "Within 10 business days" or "Within 10 calendar days"

❌ "5 working days" (vague in some contexts)

✓ "5 business days (Monday-Friday, excluding holidays)"

❌ "By next week" (when does week start?)

✓ "By Friday, January 26, 2026"

❌ "ASAP" (legally meaningless)

✓ "Within 2 business days" or specific date

❌ "Soon" or "promptly" (unenforceable)

✓ "Within 5 business days"

Court interpretations:

Courts usually interpret "business days" as Mon-Fri excluding holidays, but variations exist. Explicit definitions win disputes.