Freshdesk offers two different ways in which you can calculate your SLAs - Calendar hours- which includes your non-working hours as well as holidays, and Business hours- which are your official working hours only.

Understanding Business Hours

Business Hours refer to your company's working hours. When chosen, anything outside your working hours, including calls, will not be timed by Freshdesk. You can specify working hours for each day, allowing you to meet SLAs for multiple time zones within the same week, if necessary. 

You can set your timings via Admin > Team > Business hours. To create a new business hour setting, click on New Business Hours; or click Edit to modify previously-created business hours.

Understanding Calendar Hours

Calendar hours are regular full-day round-the-clock hours. If you're promising your customers 24/7 support, you need to use calendar hours as the basis of your SLA policies. Calendar Hours are more suited to high-priority and urgent priority tickets, which require immediate attention from your team even if it's a weekend or a holiday.

For example, if a ticket is due in six hours on a Friday evening, you'll have no problem waiting till Monday morning to resolve it if your SLA is per business hours. However, if it's in calendar hours, you'll want to resolve it immediately to ensure a spotless SLA report.