Most of the world does not change its clocks
Around 70 countries change their clocks. The majority of the world's population does not — including India, China, Japan, Brazil and Russia.
The headline numbers
Roughly 70 countries observe some seasonal clock change, concentrated in Europe, North America and parts of Oceania and South America. Most of Asia and Africa does not, and those regions hold the majority of the world's population.
Major economies that opted out
| Country | Offset | Notes |
|---|---|---|
| India | UTC+5:30 | Never adopted it nationally |
| China | UTC+8 | Abandoned in 1991; one zone nationwide |
| Japan | UTC+9 | Brief post-war trial, then dropped |
| Russia | UTC+3 (Moscow) | Abolished seasonal changes in 2014 |
| Brazil | UTC−3 (Brasília) | Abolished in 2019 |
| Türkiye | UTC+3 | Fixed to permanent summer time in 2016 |
The ones that changed recently
Brazil's 2019 decision is the most consequential recent change for international business, because it removed a seasonal shift that used to affect every São Paulo–Europe relationship. Türkiye's 2016 move to permanent summer time had a similar effect for Istanbul.
Both are a reminder that offsets are policy, not physics. Software that hard-codes them ages badly, which is exactly why the IANA database exists and is updated several times a year.
Why it matters for scheduling
A pair of zones drifts only if one changes and the other does not. London to Mumbai drifts twice a year; Mumbai to Dubai never does. When you are choosing where to place a standing meeting, a pair where neither side changes clocks is materially less trouble.
What this means for a US or European team
The practical rule is simple: a pair drifts only when one side changes and the other does not. That divides your relationships into two groups.
| Pair | Gap | Drifts? |
|---|---|---|
| New York ↔ London | 5 hours | Yes, for about four weeks a year |
| London ↔ Berlin | 1 hour | No |
| New York ↔ Los Angeles | 3 hours | No |
| London ↔ Mumbai | 4.5 / 5.5 hours | Yes, twice a year |
| New York ↔ Phoenix | 2 / 3 hours | Yes, twice a year |
| London ↔ Dubai | 3 / 4 hours | Yes, twice a year |
Choosing partners with scheduling in mind
It sounds trivial until you run a support rota. A follow-the-sun handover between London, New York and Sydney needs re-checking three times a year because all three change on different dates. The same rota between London, Dubai and Singapore only moves when London does.
The recent changes worth knowing
- Brazil, 2019. Abolished daylight saving, removing a seasonal shift against Europe.
- Türkiye, 2016. Fixed permanently at UTC+3, so it now drifts against the EU twice a year.
- Russia, 2014. Abolished seasonal changes after briefly trying permanent summer time.
- Mexico, 2022. Ended daylight saving for most of the country, changing its relationship with the US.
Each of those landed in the IANA database within weeks. Anything built on a hard-coded offset table needed a code change instead.
Filed under Reference · Tags: daylight saving, countries, dst. Figures verified against the official definitions — see our editorial policy.