GMT to BST Converter
Convert time between Greenwich Mean Time (GMT) and British Summer Time (BST)
Greenwich Mean Time (GMT)
British Summer Time (BST)
Time Difference
British Summer Time (BST) is 0 hours ahead of Greenwich Mean Time (GMT)
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Select Time
Quick Reference
| GMT | BST |
|---|---|
| 02:00 | 02:00 |
| 04:00 | 04:00 |
| 06:00 | 06:00 |
| 08:00 | 08:00 |
| 10:00 | 10:00 |
| 12:00 | 12:00 |
| 14:00 | 14:00 |
| 16:00 | 16:00 |
| 18:00 | 18:00 |
| 20:00 | 20:00 |
| 22:00 | 22:00 |
| 00:00 | 00:00 |
Top 10 Most Common Time Zones
| Abbreviation | Full Name | UTC Offset | Typical Use |
|---|---|---|---|
| UTC | Coordinated Universal Time | UTC ±0 | Global reference standard (servers, logs, APIs) |
| EST / EDT | Eastern (US) Time | UTC −5 / −4 | New York, Toronto — North American business hub |
| CST / CDT | Central (US) Time | UTC −6 / −5 | Chicago, Dallas — US central business region |
| PST / PDT | Pacific (US) Time | UTC −8 / −7 | San Francisco, Los Angeles — tech industry standard |
| GMT / BST | Greenwich Mean / British Summer Time | UTC 0 / +1 | UK, used globally as a reference with UTC |
| CET / CEST | Central European (Summer) Time | UTC +1 / +2 | Paris, Berlin, Amsterdam — EU business core |
| IST | India Standard Time | UTC +5:30 | India — major IT & outsourcing region |
| CST | China Standard Time | UTC +8 | Beijing, Shanghai — East Asia business hub |
| JST | Japan Standard Time | UTC +9 | Tokyo — finance & tech hub |
| AEST / AEDT | Australian Eastern (Daylight) Time | UTC +10 / +11 | Sydney, Melbourne — APAC regional business |
Why Time Zone Abbreviations Are Ambiguous
Unlike standardized identifiers (like America/New_York or Europe/London from the IANA tz database), abbreviations such as "CST" or "IST" are not globally unique. They can refer to different time zones depending on context — country, region, or even time of year (due to daylight saving time).
Common Ambiguous Time Zone Abbreviations
| Abbrev. | Common Meaning(s) | UTC Offset | Region(s) |
|---|---|---|---|
| CST | Central Standard Time / China Standard Time / Cuba Standard Time | UTC−6 / UTC+8 / UTC−5 | North America, China, Cuba |
| IST | Indian Standard Time / Irish Standard Time / Israel Standard Time | UTC+5:30 / UTC+1 / UTC+2 | India, Ireland, Israel |
| AST | Atlantic Standard Time / Arabia Standard Time | UTC−4 / UTC+3 | Caribbean, Canada, Middle East |
| PST | Pacific Standard Time / Philippine Standard Time | UTC−8 / UTC+8 | North America, Philippines |
| EST | Eastern Standard Time (North America / Australia) | UTC−5 / UTC+10 | North America, Australia |
✅ Best Practice
To avoid ambiguity, always:
- Use IANA tz identifiers — e.g.,
America/New_Yorkinstead of "EST" - Specify UTC offset explicitly — e.g.,
UTC−5when abbreviations must be used - Include the full timezone name — e.g., "Eastern Standard Time (EST)" with UTC offset
Related Time Zone Conversions
About GMT to BST Time Conversion
Converting time from Greenwich Mean Time (GMT) to British Summer Time (BST) is essential for understanding UK timezone changes. GMT is UTC+0 and is used from late October to late March, while BST is UTC+1 and is used from late March to late October. Both are UK timezones, representing the shift for daylight saving time.
This conversion is important for anyone in the UK or coordinating with UK colleagues and businesses. During the transition periods, accurate time conversion prevents scheduling errors, missed meetings, and confusion in international coordination. The 1-hour difference between GMT and BST affects all time calculations with other regions.
Common Use Cases for GMT to BST Conversion
Business & Work
- Understanding UK timezone transitions during daylight saving changes
- Scheduling meetings across UK DST transitions
- Coordinating with UK teams during time change periods
- Managing calendars and reminders during timezone shifts
Personal & Travel
- Adjusting personal schedules during daylight saving transitions
- Planning international calls with UK residents
- Scheduling events before and after clocks change
- Understanding UK time references in media and news
Time Zone Information
Greenwich Mean Time (GMT)
- UTC Offset: UTC+0
- IANA Timezone: Europe/London
- Daylight Saving: Used from last Sunday in October to last Sunday in March
- Major Cities: London, Edinburgh, Cardiff, Belfast, Dublin
- Coverage: United Kingdom and Ireland (winter time)
British Summer Time (BST)
- UTC Offset: UTC+1
- IANA Timezone: Europe/London
- Daylight Saving: Used from last Sunday in March to last Sunday in October
- Major Cities: London, Edinburgh, Cardiff, Belfast, Dublin
- Coverage: United Kingdom and Ireland (summer time)
Quick Reference: GMT to BST
Remember: BST is always 1 hour ahead of GMT. BST is active from late March to late October. Outside these dates, the UK observes GMT.
Frequently Asked Questions
What is the time difference between GMT and BST?
Greenwich Mean Time (GMT) is UTC+0, while British Summer Time (BST) is UTC+1. This means BST is 1 hour ahead of GMT. When it's 12:00 PM (noon) in GMT, it's 1:00 PM (13:00) in BST. Both are UK timezones, with GMT used in winter and BST used in summer.
When is BST active in the UK?
British Summer Time (BST) is active from the last Sunday in March to the last Sunday in October. During these months, clocks are set forward by 1 hour from GMT. Outside this period (late October to late March), the UK observes Greenwich Mean Time (GMT).
Why does the UK have two different timezones?
The UK observes daylight saving time to make better use of daylight hours. During summer months when days are longer, BST shifts clocks forward to extend evening daylight. This helps reduce energy consumption and provides more daylight hours for business and leisure activities. During winter months with shorter days, GMT is used.
How does GMT to BST conversion affect international business?
GMT to BST conversion is important for understanding UK timezone changes when coordinating international meetings. The shift from GMT to BST changes the offset with other timezones. For example, UK to US East Coast changes from 5 hours (GMT to EST) to 4 hours (BST to EDT). It's crucial to account for this transition date in global scheduling.
What is the clocks change date?
The UK changes from GMT to BST on the last Sunday of March at 1:00 AM GMT (clocks spring forward to 2:00 AM BST). The reverse change from BST to GMT happens on the last Sunday of October at 2:00 AM BST (clocks fall back to 1:00 AM GMT). Most of Europe follows similar but sometimes different dates.
Is this conversion relevant for most people?
Yes, this conversion is essential for anyone in the UK or coordinating with UK colleagues during the transition period. Understanding the difference between GMT and BST helps with scheduling meetings across DST changes, setting reminders correctly, and managing calendars during the twice-yearly timezone shift.
Pro Tips
- • The 1-hour difference between GMT and BST is straightforward - just add 1 hour to GMT time to get BST time.
- • Mark your calendar for the last Sunday of March (GMT to BST) and last Sunday of October (BST to GMT) to remember transition dates.
- • During the transition week, be extra careful with scheduling as different systems and countries may transition on different dates.
- • Many other countries have different daylight saving transition dates, so be aware when scheduling international meetings.
- • Check your phone and computer settings - most devices automatically update between GMT and BST in the UK.
- • Remember: when the UK is on BST, the time difference with other regions changes by 1 hour compared to GMT periods.
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