Flight Time
18,316 km
Distance
18,316 km
11,381 mi
Flight Time
21h 53m to 24h 22m
🇰🇷 Seoul → 🇧🇷 São Paulo
ICN to GRU — Complete travel planning guide
Time Difference
00:28
Seoul
-12h
difference
12:28
São Paulo
Jet Lag Severity
MildModerateSevere
severe
Severity
12
Zones crossed
9d
To adjust
Adjustment Timeline
Day 1
07:00 – 20:00
Day 2
05:00 – 20:00
Day 3
05:00 – 20:00
Day 4
05:00 – 20:00
Day 5
05:00 – 20:00
Day 6
05:00 – 20:00
Day 7
05:00 – 20:00
Day 8
05:00 – 22:00
Day 9
05:00 – 23:00
Evidence-based recommendations
Each recommendation below is graded by how strongly published research supports it, with the source it comes from. Optimal timing depends on your travel direction, the number of time zones crossed and your own circadian phase, so treat the schedule as a starting point.
Seek morning light
StrongBright light after your destination wake time helps advance your body clock when travelling east.
CDC Yellow Book 2026Limit light in the local evening
StrongLight at the wrong hour can push your clock the opposite way, so dim screens and lights before your target bedtime.
NIH — Circadian rhythmsShift bedtime earlier before departure
ModerateMoving sleep and wake times 30-60 minutes earlier for a few nights gives your clock a head start on an eastward trip.
CDC Yellow Book 2026Live on destination time on arrival
ModerateSleeping, eating and being active on local time gives your body consistent cues about the new day.
CDC Yellow Book 2026Consider timed melatonin
ModerateLow-dose melatonin near the local bedtime can help with sleep timing after crossing several zones; timing matters more than dose.
Cochrane review — Melatonin for jet lagUse caffeine early, not late
Practical adviceCaffeine can help you stay awake during local daytime, but late doses tend to delay sleep onset.
CDC Yellow Book 2026Protect sleep around the flight
Practical adviceArriving without a large sleep debt makes the first days easier, even when few time zones are involved.
CDC Yellow Book 2026
How we grade evidence
- Strong
- Consistently supported by controlled circadian research and current public-health guidance.
- Moderate
- Supported by research, but effect size and best timing vary between individuals and studies.
- Practical advice
- Sensible travel habits with limited direct evidence for shifting the body clock.
This is general travel information, not medical advice. Talk to a clinician before using melatonin or sleep medication, especially if you are pregnant, take other medication or have a sleep disorder.
Flying the other way?São Paulo → Seoul
Flying from Seoul to São Paulo
The flight from Seoul (ICN) to São Paulo (GRU) covers approximately 18,316 kilometers (11,381 miles) based on the great-circle distance between both airports. This is the shortest theoretical path over Earth's surface, though actual flight paths may be slightly longer due to air traffic routing, weather avoidance, and airspace restrictions.
The estimated non-stop flight time is 21h 53m to 24h 22m, assuming a modern jet cruising at approximately 850 km/h. This gate-to-gate estimate includes time for taxi, takeoff, climb, cruise, descent, and landing. Actual duration varies based on wind conditions — particularly the jet stream — aircraft type, and airport congestion at both ends.
São Paulo is 12 hours behind Seoul. Travelers crossing 12 time zones eastward can expect severe jet lag, with full circadian adjustment typically taking about 9 days.
Since you're traveling eastward, your body clock needs to advance — meaning you'll need to go to bed earlier and wake up earlier than feels natural. Strategic morning light exposure at your destination is the most effective way to accelerate this adjustment.
Route facts: ICN → GRU
| Detail | ICN | GRU |
|---|---|---|
| Airport | Incheon International (ICN) | São Paulo–Guarulhos International (GRU) |
| City & country | 🇰🇷 Seoul, KR | 🇧🇷 São Paulo, BR |
| Coordinates | 37.46°N, 126.44°E | 23.44°S, 46.47°W |
| IANA time zone | Asia/Seoul | America/Sao_Paulo |
| Current UTC offset | UTC+9 | UTC-3 |
| Local time now | 00:28 | 12:28 |
Flight path, direction and distance
Leaving Seoul, the great-circle track to São Paulo starts on an initial bearing of about 335° (NNW). The route measures 18,316 km, or 9,890 nautical miles — the unit airlines actually plan with. Because the shortest path on a sphere is a curve rather than a straight line on a flat map, the real track may look like it bends far north or south of the direct line you would draw on a wall map.
At this length the sector counts as ultra-long-haul at around 23h 8m. Aircraft on these rotations carry extra crew, plan an extended dark-cabin period, and fuel load can force payload restrictions on hot days.
This is an international sector, so allow additional time for immigration and customs on arrival — typically 30 to 60 minutes on top of the block time before you are landside.
The route crosses the equator, so you switch hemispheres. Seasons are reversed between the two ends: plan clothing for the opposite season, and expect a noticeable change in daylight length rather than just a change of clock time.
Departure and arrival times: Seoul to São Paulo
Using an estimated block time of 23h 8m and the current offset between the two cities, this table shows what local time you would land in São Paulo for common departure times from Seoul. Use it to pick a departure that puts your arrival in daylight, which makes the first day of adjustment much easier.
| Departure (Seoul) | Arrival (São Paulo) | Arrival day |
|---|---|---|
| 06:00 | 17:08 | Same day |
| 10:00 | 21:08 | Same day |
| 14:00 | 01:08 | Next day |
| 18:00 | 05:08 | Next day |
| 22:00 | 09:08 | Next day |
Times are estimates based on great-circle distance and current time zone offsets, not airline schedules. Always confirm with your carrier.
Daylight: Seoul vs São Paulo
Daylight length is what actually resets your body clock, and it differs between Seoul and São Paulo through the year. In São Paulo the day runs from about 10.7 h to 13.6 h across the four dates below, which changes how much morning or evening light you can realistically get after landing.
| Date | Sunrise Seoul | Sunrise São Paulo | Sunset São Paulo | Day length vs origin |
|---|---|---|---|---|
| March equinox · March 20 | 06:40 | 06:10 | 18:18 | ±0 |
| June solstice · June 21 | 05:13 | 06:47 | 17:28 | −4.1 h |
| September equinox · September 22 | 06:21 | 05:56 | 18:01 | −0.1 h |
| December solstice · December 21 | 07:45 | 05:16 | 18:51 | +4 h |
Your light window in São Paulo
Flying east, light in the first hours after sunrise pulls your clock earlier. In São Paulo that puts the useful window at roughly 06:10–09:10. Keep light low around 15:18–18:18, when late light would push your clock the wrong way. Timing depends on your own circadian phase, so treat these as starting points.
Body clock time on arrival in São Paulo
Before any adjustment, your body still runs on Seoul time. When it is 08:00 in São Paulo, your body thinks it is 20:00 — which is why local mealtimes and meetings can feel so far off on day one.
| São Paulo clock | Your body clock | What your body expects |
|---|---|---|
| 06:00 | 18:00 | Awake and alert |
| 08:00 | 20:00 | Winding down |
| 12:00 | 00:00 | Sleep |
| 16:00 | 04:00 | Deepest sleep, hardest to wake |
| 20:00 | 08:00 | Awake and alert |
| 23:00 | 11:00 | Awake and alert |
Daylight saving on this route in 2026
Seoul keeps the same offset all year (Asia/Seoul), with no daylight saving changes.
São Paulo keeps the same offset all year (America/Sao_Paulo), with no daylight saving changes.
The gap between Seoul and São Paulo stays at 12 h all year, so your travel date does not change the time difference.
Estimated adjustment curve
Eastward travel asks your body clock to run earlier, which it does more slowly — roughly an hour a day. For 12 time zones that models out to about 9 days before local time and body time line up.
Day 1
11% · 10.7 h left
Day 2
22% · 9.3 h left
Day 3
33% · 8 h left
Day 4
44% · 6.7 h left
Day 5
56% · 5.3 h left
Day 6
67% · 4 h left
Day 7
78% · 2.7 h left
Day 8
89% · 1.3 h left
Day 9
100% · 0 h left
Return trip: São Paulo back to Seoul
| Leg | Direction | Time zones | Modelled recovery |
|---|---|---|---|
| ICN → GRU | eastward | 12 | 9 days |
| GRU → ICN | eastward | 12 | 9 days |
The trip home is usually the easier half of this route: about 9 days outbound versus 9 days on the way back, since the return direction matches the way your clock drifts naturally.