CAT is 2 hours ahead of GMT. When it's 12:00 in London on GMT, it's 14:00 in Johannesburg, Harare, or Lusaka. But the gap isn't always that neat: the UK shifts to BST in spring, and CAT never moves.
The CAT to GMT rule
Scheduling between Central Africa and the UK comes down to one split:
- Late October to late March (UK on GMT): CAT is 2 hours ahead. London 10:00 = CAT 12:00.
- Late March to late October (UK on BST): CAT is 1 hour ahead. London 10:00 = CAT 11:00.
No ambiguity on the African side. CAT is fixed at UTC+2 year-round. CAT countries don't touch their clocks.
GMT, BST, and CAT side by side
Three abbreviations, three offsets:
| Zone | Offset | Who uses it |
|---|---|---|
| GMT (Greenwich Mean Time) | UTC+0 | UK in winter, Ghana, Ivory Coast, Senegal |
| BST (British Summer Time) | UTC+1 | UK in summer only |
| CAT (Central Africa Time) | UTC+2 | South Africa, Zimbabwe, Zambia, DRC (east), and more |
The UK runs on GMT from late October to late March. Then it jumps forward to BST. Central Africa stays put. That's why the difference shrinks from 2 hours to 1 hour every spring.
CAT to GMT conversion table
The left column is CAT. The right is GMT (UK winter time).
| CAT (UTC+2) | GMT (UTC+0) |
|---|---|
| 06:00 | 04:00 |
| 08:00 | 06:00 |
| 10:00 | 08:00 |
| 12:00 | 10:00 |
| 14:00 | 12:00 |
| 16:00 | 14:00 |
| 18:00 | 16:00 |
| 20:00 | 18:00 |
| 22:00 | 20:00 |
For BST (UK summer), subtract one hour from the CAT column instead of two.
Best times to call between CAT and the UK
The workable window is wider in winter.
UK on GMT (winter): CAT is 2 hours ahead. A 09:00 London start is 11:00 in CAT countries, comfortable for both sides. The last practical call from London is around 15:00 GMT, which lands at 17:00 CAT.
UK on BST (summer): The gap narrows to 1 hour. London 09:00 is CAT 10:00. You can call later into the UK afternoon without hitting evening in Africa.
The sweet spot for a call from London to Johannesburg, Harare, or Lusaka: 10:00-14:00 GMT in winter, 09:00-15:00 BST in summer. That covers the UK morning and the CAT late morning or early afternoon.
How BST scrambles the CAT-UK gap
The UK changes clocks on the last Sunday of March and the last Sunday of October. CAT doesn't change at all.
The annual cycle:
- Late October to late March: 2 hours (CAT ahead)
- Late March to late October: 1 hour (CAT ahead)
One trap: the transition dates aren't the same everywhere. The UK follows European DST rules. Morocco also observes DST but suspends it during Ramadan. That's a different comparison entirely.
For CAT specifically, none of that applies. South Africa, Zimbabwe, Zambia, Mozambique, Malawi, and the eastern DRC are all on CAT year-round. No exceptions. No clock changes.
If you're scheduling a recurring call, bookmark the winter and summer rules separately. The 2-hour gap in January becomes a 1-hour gap in July, and many people miss the change when the UK springs forward.
What countries are on CAT?
Central Africa Time (UTC+2) is used by South Africa, Zimbabwe, Zambia, Mozambique, Malawi, Rwanda, Burundi, Botswana, Namibia, South Sudan, and the eastern half of the Democratic Republic of the Congo.
Is CAT the same as SAST?
Yes, in practice. South African Standard Time is also UTC+2 year-round. The name differs, but the offset and rules are identical to CAT.
Does the UK observe GMT all year?
No. The UK uses GMT in winter and British Summer Time (UTC+1) from late March to late October. That's why the difference with CAT shifts from 2 hours to 1 hour.
When does the UK change to BST in 2026?
The UK moves to BST on the last Sunday of March and back to GMT on the last Sunday of October. Between those dates, CAT is 1 hour ahead of London.
Why doesn't CAT observe daylight saving time?
CAT countries stay fixed at UTC+2. Near the equator, daylight hours don't vary enough across seasons to make DST worthwhile. Southern Africa's winter days are still reasonably long.
What's the difference between GMT and UTC?
GMT is a time zone (UTC+0). UTC is the time standard. For conversion purposes, they're interchangeable when the UK is on GMT. The distinction only matters when you're dealing with the technical standard itself.