What is the time difference between GST and JST?

Japan Standard Time (JST) is 5 hours ahead of Gulf Standard Time (GST). GST uses a UTC offset of UTC+4, while JST uses UTC+9. For example, when it's 9:00 AM in GST, it's 2:00 PM in JST. This difference remains constant year-round since neither timezone observes daylight saving time. Use the conversion table above to see the exact time for each hour of the day.

How do I convert GST to JST?

To convert GST to JST, add 5 hours to the GST time. For example, 9:00 AM GST is 2:00 PM JST, and 5:00 PM GST is 10:00 PM JST. Since neither timezone observes DST, this conversion stays the same all year. You can also use the interactive converter above for quick, accurate results.

What time is it in JST when it's noon in GST?

When it's 12:00 PM (noon) in GST, it's 5:00 PM in JST. This is because JST is 5 hours ahead of GST. Similarly, when it's 6:00 PM in GST, it's 11:00 PM in JST. This relationship is constant throughout the year. The color-coded conversion table above shows every hour mapped between both timezones.

How many hours ahead is JST from GST?

JST is 5 hours ahead of GST. This means when it's 9:00 AM in GST, it's 2:00 PM in JST, and when it's midnight in GST, it's 5:00 AM in JST. This offset is constant throughout the year since neither timezone uses daylight saving time. The conversion table above provides a complete hour-by-hour mapping.

Is JST ahead or behind GST?

JST is ahead of GST by 5 hours. Clocks in JST show a later time than GST, meaning the day starts earlier in JST relative to GST. For example, when it's morning in GST, it's later in the morning in JST. This difference stays the same year-round.

Does GST observe daylight saving time?

No, Gulf Standard Time does not observe daylight saving time. The UTC offset of UTC+4 remains the same year-round, making time conversions from GST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

Does JST observe daylight saving time?

No, Japan Standard Time does not observe daylight saving time. The UTC offset of UTC+9 remains the same year-round, making time conversions to JST more predictable. Countries and regions in this timezone keep their clocks unchanged regardless of the season.

What is the best time to call from GST to JST?

The best time for a call between GST and JST is during overlapping business hours (9 AM – 5 PM) in both timezones. To reach someone in JST during their work day, call between 4:00 AM and 12:00 PM your GST time. Avoid calling too early or late, as the 5 hours difference means your evening could be their late night. Check the color-coded conversion table above — green hours indicate business hours in both zones, making it easy to find the ideal time.

Do GST and JST ever have the same time?

No, GST and JST are always 5 hours apart and never display the same clock time simultaneously. Neither timezone observes DST, so the difference is constant year-round with no seasonal variation. The 5 hours offset is determined by their fixed positions relative to the Prime Meridian (UTC). You can always rely on this consistent difference when planning across these timezones.

GST to JST Converter

Convert Gulf Standard Time to Japan Standard Time. See the hour-by-hour conversion table below.

Timezone Details

Gulf Standard Time

7:42 AM

Friday, April 3, 2026

GST (UTC+04:00)

Japan Standard Time

12:42 PM

Friday, April 3, 2026

JST (UTC+09:00)

Difference: +5 hours

GST DST: No

JST DST: No

24-Hour Overview

GST — 24-hour overview

12a12a

3a3a

6a6a

9a9a

10a

11a

12p12p

3p3p

6p6p

9p9p

10p

11p

NightMorningBusinessEvening

JST — 24-hour overview

5a5a

8a8a

10a

11a11a

12p

2p2p

5p5p

8p8p

10p

11p11p

12a

2a2a

NightMorningBusinessEvening

Frequently Asked Questions

Related Conversions

JST to GST EST to JST JST to EST PST to JST JST to PST GMT to JST JST to GMT IST to JST JST to IST

Cities in These Timezones

GST Cities

Dubai Abu Dhabi

JST Cities

Tokyo Osaka Fukuoka

More Tools

Compare GST & JST Plan a Meeting (GST & JST)See on Map

Learn More

How Time Zones Work Understanding DST Timezone Abbreviations

External Resources

Gulf Standard Time on Wikipedia Japan Standard Time on Wikipedia IANA Time Zone Database