Business Days Calculator API: Complete Developer Guide

Need to calculate business days between dates or add working days to a date? This guide covers everything about business day calculation via API, including handling weekends, holidays, and implementation examples in multiple programming languages.

What are Business Days?

Business days (or working days) are days when businesses typically operate - usually Monday through Friday, excluding public holidays. Different countries and industries may have different definitions.

Example: From Monday Jan 1 to Friday Jan 12 = 9 business days (excluding 2 weekends)

Calculation Complexity

Factors that make business day calculation complex:

Weekends

Most countries use Saturday-Sunday weekends, but some use Friday-Saturday.

Public Holidays

Holidays vary by country, region, and even company.

Regional Differences

Different countries have different working weeks and holiday schedules.

Using the Business Days API

TinyFn provides a flexible endpoint to calculate business days:

GET https://api.tinyfn.io/v1/time/business-days?start=2024-01-01&end=2024-01-15
Headers: X-API-Key: your-api-key

{
  "start_date": "2024-01-01",
  "end_date": "2024-01-15",
  "business_days": 10,
  "total_days": 14,
  "weekends": 4,
  "holidays_excluded": 0,
  "weekend_days": ["saturday", "sunday"]
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/time/business-days?start=2024-01-01&end=2024-01-31&country=US',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const result = await response.json();
console.log(`Business days: ${result.business_days}`);

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/time/business-days',
    params={'start': '2024-01-01', 'end': '2024-01-31', 'country': 'US'},
    headers={'X-API-Key': 'your-api-key'}
)
result = response.json()
print(f"Business days: {result['business_days']}")

cURL

curl "https://api.tinyfn.io/v1/time/business-days?start=2024-01-01&end=2024-01-31&country=US" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Shipping Estimates: Calculate delivery dates based on business days
• SLA Tracking: Measure response times in business days
• Project Planning: Estimate project durations accurately
• Payment Terms: Calculate due dates (e.g., Net 30 business days)
• HR Systems: Track working days for payroll and PTO

Best Practices

1. Know your audience: Use appropriate country/region for holidays
2. Document assumptions: Clarify what counts as a business day
3. Handle edge cases: Consider what happens when start/end are weekends
4. Update holidays: Keep holiday lists current for accurate results