Quick answer
Calendar days include all days: Monday to Sunday, including bank holidays. Business days are different and usually skip weekends.
Simple example
If a deadline says 5 calendar days from Monday, and the start date is excluded, you count Tuesday, Wednesday, Thursday, Friday, Saturday.
If the same deadline says 5 business days, weekends are skipped and the result is usually later.
Why this matters
- Delivery windows can look shorter or longer depending on wording.
- Complaint and service deadlines may use different rules.
- Contract/payment dates can be missed when calendar and business days are mixed up.
Calendar days vs business days
| Term | What it counts | Weekend included? |
|---|---|---|
| Calendar days | Every day on the calendar | Yes |
| Business days | Usually Mon" · “Fri working days | No |
Clear yes/no answer summary
If you only have ten seconds, here is the answer you need:
| Question | Answer | Note |
|---|---|---|
| Do calendar days include Saturdays? | Yes | Saturday is a calendar day like any other. |
| Do calendar days include Sundays? | Yes | Sunday counts, even if no business operates that day. |
| Do calendar days include bank holidays? | Yes | Calendar days count every day, including public holidays. |
| Do business days include weekends? | No | Business days skip Saturday and Sunday by default. |
| Do business days include bank holidays? | Usually no | Most policies exclude them, but check the specific wording. |
| Can “days” without a prefix mean calendar days? | Usually yes | In UK legal and consumer contexts, “days” defaults to calendar days. |
Worked examples from different starting days
The starting day dramatically affects when a calendar-day deadline lands. Here are two worked comparisons:
Starting on a Wednesday
If you receive a notice on Wednesday and the deadline is 7 calendar days (excluding the start date):
| Day | Date example | Count | Notes |
|---|---|---|---|
| Wed | 10 Jun | Start (day 0) | Notice received |
| Thu | 11 Jun | Day 1 | Weekday |
| Fri | 12 Jun | Day 2 | Weekday |
| Sat | 13 Jun | Day 3 | Weekend — still counts! |
| Sun | 14 Jun | Day 4 | Weekend — still counts! |
| Mon | 15 Jun | Day 5 | Weekday |
| Tue | 16 Jun | Day 6 | Weekday |
| Wed | 17 Jun | Day 7 — deadline | Deadline lands on a weekday |
By business-day counting, 7 business days from a Wednesday would land on the following Friday (26 June), skipping both weekends in between — a full 9 days later.
Starting on a Friday
If you receive a notice on Friday and the deadline is 3 calendar days:
| Day | Date example | Count |
|---|---|---|
| Fri | 5 Jun | Start (day 0) |
| Sat | 6 Jun | Day 1 |
| Sun | 7 Jun | Day 2 |
| Mon | 8 Jun | Day 3 — deadline |
Three calendar days from a Friday lands on Monday. If the same rule said 3 business days, the deadline would slip to Wednesday 10 June — a midweek deadline instead of a Monday one.
How different industries use the terms
Not every sector treats these terms the same way. Knowing the industry norm helps you interpret what a deadline really means:
| Industry | Typical default | Why |
|---|---|---|
| E-commerce & retail | Calendar days for returns; business days for delivery | Consumer law mandates calendar days for cancellation rights; couriers quote business days for shipping estimates. |
| Financial services | Business days | FCA rules, payment processing, and trading all use business days. Weekends are not banking days. |
| Legal & courts | Calendar days (with roll-forward rules) | Court deadlines are calendar days, but if a deadline falls on a weekend or holiday it typically rolls to the next business day. |
| Public sector & FOI | Working days | FOI requests in the UK must be answered within 20 working days. The clock does not tick on weekends. |
| Employment & HR | Calendar days for notice; business days for processing | Statutory notice is calendar-based. Internal HR processes (payroll changes, onboarding) often reference business days. |
| Insurance | Business days | Claims handling and underwriting timelines typically use business days to reflect office hours. |
What to check in contracts and policies
Before you rely on a deadline, scan the document for these five things:
- The exact wording. Does it say “calendar days,” “business days,” “working days,” or just “days”? If only “days” appears, look for a definitions section.
- The definitions clause. Many contracts include a section near the beginning that defines key terms. “Business day” may be defined as “a day other than Saturday, Sunday, or a bank holiday in England and Wales.”
- Jurisdiction. Which country’s bank holidays apply? A “business day in England” is not necessarily a business day in Scotland, which has different bank holidays.
- Time of day cut-off. Some contracts specify that notices received after 5pm count as received the next day. This can add another day to the clock.
- Weekend/holiday rollover. Does the deadline shift to the next business day if it falls on a non-working day, or does it stay fixed? This varies by jurisdiction and contract.
Frequently asked questions
Does “within 7 days” include today?
Generally no. “Within 7 days of receiving this notice” starts counting from the day after receipt. However, always verify — some contracts explicitly include the day of receipt as day one. If the contract is silent, the common-law position in England and Wales is that the day of the event is excluded.
Do calendar days include Christmas Day?
Yes. Calendar days count every day of the year. Even Christmas Day, Boxing Day, and New Year’s Day are counted. A 7-calendar-day deadline spanning Christmas may push the deadline to Christmas Day itself, though many organisations will pragmatically extend to the next working day.
Can a deadline fall on a Sunday?
Yes, under calendar-day counting, deadlines can land on Sundays. Whether you are expected to act on a Sunday depends on the context. For consumer returns, you don’t need to post a return on a Sunday; you just need to notify the seller of your cancellation by that date.