CAT to AST
-6hCAT
CATSOURCEAST
ASTGreen rows indicate typical business hours (9 AM - 5 PM)
CAT and AST on the World Map
The map below highlights the CAT (Central Africa Time) and AST (Atlantic Standard Time) timezone regions across the globe.
CAT – Central Africa Time
UTC+02:00Central Africa Time (CAT, UTC+02:00) covers Zimbabwe, Zambia, Mozambique, Malawi and neighbouring countries.
- •Central Africa Time is fixed at UTC+02:00 with no daylight saving.
- •CAT matches South Africa Standard Time (SAST) all year.
- •It is the same offset as Central European Time in winter.
- •Harare is level with Johannesburg and one hour ahead of Lagos.
AST – Atlantic Standard Time
UTC-04:00Atlantic Standard Time (AST) is the time zone for the Canadian Atlantic provinces and the Caribbean, 4 hours behind UTC.
- •Puerto Rico uses AST year-round and does not observe DST.
- •AST is 1 hour ahead of EST.
- •Halifax, the capital of Nova Scotia, is the largest city in AST Canada.
Understanding the -6h Gap: CAT vs AST
CAT runs on Central Africa Time (CAT) at UTC+02:00. AST runs on Atlantic Standard Time (AST) at UTC-04:00. That puts CAT 6 hours behind AST — a difference of -6h at the current offsets.
In practice, when it is 9:00 AM in CAT it is 3:00 AM in AST. Midnight in CAT is 6:00 PM in AST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
CAT to AST time conversion table
| CAT (CAT) | AST (AST) | Day |
|---|---|---|
| 12:00 AM | 6:00 PM | previous day |
| 6:00 AM | 12:00 AM | same day |
| 7:00 AM | 1:00 AM | same day |
| 8:00 AM | 2:00 AM | same day |
| 9:00 AM | 3:00 AM | same day |
| 12:00 PM | 6:00 AM | same day |
| 3:00 PM | 9:00 AM | same day |
| 5:00 PM | 11:00 AM | same day |
| 6:00 PM | 12:00 PM | same day |
| 9:00 PM | 3:00 PM | same day |
Why people convert CAT to AST time
- Scheduling a call from CAT to AST: a 10:00 AM start in CAT lands at 4:00 AM in AST, so you can confirm the slot without doing the arithmetic yourself.
- Finding shared working hours: both CAT and AST are inside the 9-to-5 working day between 3:00 PM and 5:00 PM CAT time (9:00 AM–11:00 AM AST). That is roughly 2 hours of usable overlap.
- Keeping family and friends in sync: knowing that 8:00 PM in CAT is 2:00 PM in AST makes it easy to avoid calling at 3 AM.
- Always state the zone abbreviation, not just the hour. "3:00 PM CAT" is unambiguous; "3 PM" across a -6h gap is not.
- Block 3:00 PM–5:00 PM CAT as the recurring meeting window if you work primarily from CAT and need AST colleagues present.
About CAT (Central Africa Time)
Central Africa Time (CAT) is fixed at UTC+02:00 all year across a broad belt of southern and central Africa, including Zimbabwe, Zambia, Mozambique, Malawi, Rwanda, Burundi and the eastern Democratic Republic of the Congo. None of these countries observes daylight saving time, so CAT never shifts. It is the same offset as South Africa Standard Time (SAST) and the winter version of Central European Time, which makes CAT a convenient bridge between African, European and Middle Eastern schedules — Harare is level with Johannesburg all year and one hour ahead of Lagos.
About AST (Atlantic Standard Time)
Atlantic Standard Time (AST) covers Canada's Atlantic provinces (Nova Scotia, New Brunswick, Prince Edward Island, and most of Labrador), as well as several Caribbean nations. Puerto Rico and the US Virgin Islands use AST year-round without daylight saving time. The Canadian provinces switch to Atlantic Daylight Time (ADT) in summer.
Best time to call between CAT and AST
Both CAT and AST sit inside the 9 AM – 5 PM working day between 3:00 PM–5:00 PM CAT, which is 9:00 AM–11:00 AM AST. That gives roughly 2 hours of shared time — the safest window for a live call or meeting.
Business hours overlap
CAT and AST overlap for about 2 hours during the working day — enough for meetings if you avoid the edges of the window.
CAT is 6 hours behind AST (CAT UTC+02:00 → AST UTC-04:00). The shared working window is 3:00 PM–5:00 PM CAT. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
CAT
Does not observe DST
AST
☀ Currently in DST
Standard: UTC-04:00 · DST: UTC-03:00
Clocks fall back on Sun, Nov 1, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between CAT and AST?
CAT (CAT, UTC+02:00) is 6 hours behind AST (AST, UTC-04:00). The gap is currently -6h.
How do I convert CAT time to AST time?
Add -6h to CAT local time. For example, 9:00 AM in CAT is 3:00 AM in AST.
What time is it in AST right now?
AST uses AST at UTC-04:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -6h offset from CAT.
What is the best time to call AST from CAT?
Call between 3:00 PM and 5:00 PM CAT — that maps to 9:00 AM–11:00 AM AST and keeps both parties inside the working day.
Which is behind, CAT or AST?
CAT is 6 hours behind AST. When it is 12:00 PM in CAT it is 6:00 AM in AST.
Does daylight saving time affect the CAT–AST difference?
Neither zone observes daylight saving time, so the -6h offset between CAT and AST is fixed all year.
Which other cities share CAT's time zone?
CAT also covers Harare, Lusaka, Maputo, Lilongwe, Kigali.
Which countries use CAT, CAT's zone?
CAT is used in Zimbabwe, Zambia, Mozambique, Malawi, Rwanda, Burundi, DR Congo (east).
Is there a day difference between CAT and AST?
Not normally. The -6h gap only pushes the date over the previous day.
What is the time difference between CAT and AST?
AST is -6h from CAT.
What timezone is CAT in?
CAT operates on its local timezone.
What timezone is AST in?
AST operates on its local timezone.
Which countries use CAT (Central Africa Time)?
CAT is used in Zimbabwe, Zambia, Mozambique, Malawi, Rwanda, Burundi, and 1 more countries.
Does CAT observe daylight saving time?
No, CAT does not observe daylight saving time and remains at UTC+02:00 year-round.
What are some interesting facts about CAT?
Central Africa Time is fixed at UTC+02:00 with no daylight saving. CAT matches South Africa Standard Time (SAST) all year.
Which cities are in the AST timezone?
Major cities in the AST timezone include Halifax, San Juan, Santo Domingo, Caracas, La Paz, Fredericton, Charlottetown.
What is the UTC offset for AST?
Atlantic Standard Time (AST) is at UTC-04:00. During daylight saving time, it shifts to ADT.
What should I know about the AST timezone?
Puerto Rico uses AST year-round and does not observe DST. AST is 1 hour ahead of EST.
When is it midnight in CAT, what time is it in AST?
When it is 12:00 AM (midnight) in CAT (CAT), it is -6h later in AST (AST).
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