Cosmic radiation on flights from Singapore (SIN) to London (LHR)
A flight from Singapore Changi Airport to London Heathrow Airport at 35,000 ft, about 13 h 23 min in the air, receives about 0.0346 mSv (34.6 µSv) of cosmic radiation: about a third of a chest X-ray. That is the FAA's CARI-7 model run for this route with the solar conditions of August 2026.
Updated · solar conditions of August 2026
- Dose
- 34.6 µSv0.0346 mSv
- Time in the air
- 13 h 23 minestimated
- Dose rate
- 2.6 µSv/haverage, 35,000 ft
- Chest X‑rays
- 0.35at 0.1 mSv each
Key facts: SIN → LHR
| Dose, standard flight | 0.0346 mSv (34.6 µSv) |
|---|---|
| Time in the air | 13 h 23 min, estimated from distance and prevailing winds |
| Cruise altitude | 35,000 ft |
| Average dose rate | 2.6 µSv/h |
| Great-circle distance | 10,882 km (6,762 mi) |
| Furthest from the equator | 52.5°N |
| Solar conditions | August 2026 |
The standard flight is CARI-7, the FAA Civil Aerospace Medical Institute's model, run on the dev machine for this route: 35,000 ft, 13 h 23 min in the air (climb 25 min, cruise 761 min, descent 17 min), effective dose per ICRP Publication 103. How it's calculated.
How the sun changes the dose on SIN → LHR
The sun's 11-year cycle moves this number. With the same 13 h 23 min at 35,000 ft, the flight would have received 0.0395 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0296 mSv in January 2026, near solar maximum: 33% more at the quiet end. In August 2026 it is 0.0346 mSv.
The numbers behind the chart
| Month | Dose | Dose |
|---|---|---|
| January 2016 | 36.7 µSv | 0.0367 mSv |
| April 2016 | 37.3 µSv | 0.0373 mSv |
| July 2016 | 37.2 µSv | 0.0372 mSv |
| October 2016 | 38 µSv | 0.038 mSv |
| January 2017 | 38.2 µSv | 0.0382 mSv |
| April 2017 | 38.8 µSv | 0.0388 mSv |
| July 2017 | 38.4 µSv | 0.0384 mSv |
| October 2017 | 38.2 µSv | 0.0382 mSv |
| January 2018 | 38.6 µSv | 0.0386 mSv |
| April 2018 | 39.1 µSv | 0.0391 mSv |
| July 2018 | 39 µSv | 0.039 mSv |
| October 2018 | 39.5 µSv | 0.0395 mSv |
| January 2019 | 38.4 µSv | 0.0384 mSv |
| April 2019 | 39.4 µSv | 0.0394 mSv |
| July 2019 | 39.1 µSv | 0.0391 mSv |
| October 2019 | 39.4 µSv | 0.0394 mSv |
| January 2020 | 39.3 µSv | 0.0393 mSv |
| April 2020 | 39.5 µSv | 0.0395 mSv |
| July 2020 | 39.3 µSv | 0.0393 mSv |
| October 2020 | 39.3 µSv | 0.0393 mSv |
| January 2021 | 38.6 µSv | 0.0386 mSv |
| April 2021 | 39.4 µSv | 0.0394 mSv |
| July 2021 | 38.9 µSv | 0.0389 mSv |
| October 2021 | 39 µSv | 0.039 mSv |
| January 2022 | 38.5 µSv | 0.0385 mSv |
| April 2022 | 38.3 µSv | 0.0383 mSv |
| July 2022 | 36.3 µSv | 0.0363 mSv |
| October 2022 | 37 µSv | 0.037 mSv |
| January 2023 | 35 µSv | 0.035 mSv |
| April 2023 | 35.3 µSv | 0.0353 mSv |
| July 2023 | 34 µSv | 0.034 mSv |
| October 2023 | 34.1 µSv | 0.0341 mSv |
| January 2024 | 32.8 µSv | 0.0328 mSv |
| April 2024 | 33.5 µSv | 0.0335 mSv |
| July 2024 | 33.6 µSv | 0.0336 mSv |
| October 2024 | 30.8 µSv | 0.0308 mSv |
| January 2025 | 31.5 µSv | 0.0315 mSv |
| April 2025 | 31.6 µSv | 0.0316 mSv |
| July 2025 | 31.3 µSv | 0.0313 mSv |
| October 2025 | 31.9 µSv | 0.0319 mSv |
| January 2026 | 29.6 µSv | 0.0296 mSv |
| April 2026 | 32.2 µSv | 0.0322 mSv |
| July 2026 | 33.6 µSv | 0.0336 mSv |
| August 2026 | 34.6 µSv | 0.0346 mSv |
How cruise altitude changes the dose
Flown at 31,000 ft instead, the same flight would receive 0.0256 mSv, 26% less than at 35,000 ft; at 41,000 ft it would receive 0.0483 mSv, 40% more. Same route, same time in the air, same month: only the air overhead changes.
Try it: change the altitude and the month
Every combination is its own CARI-7 run for SIN → LHR, with the same 13 h 23 min in the air. It is still a standard flight, not yours: the app calculates your exact flight.
Every combination as a table (µSv)
| Altitude | Jan 2016 | Jan 2017 | Jan 2018 | Jan 2019 | Jan 2020 | Jan 2021 | Jan 2022 | Jan 2023 | Jan 2024 | Jan 2025 | Jan 2026 | Aug 2026 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 31,000 ft | 27.1 | 28.2 | 28.4 | 28.3 | 29 | 28.4 | 28.4 | 25.9 | 24.3 | 23.4 | 22 | 25.6 |
| 33,000 ft | 31.8 | 33.1 | 33.4 | 33.2 | 34 | 33.4 | 33.3 | 30.4 | 28.5 | 27.4 | 25.8 | 30 |
| 35,000 ft | 36.7 | 38.2 | 38.6 | 38.4 | 39.3 | 38.6 | 38.5 | 35 | 32.8 | 31.5 | 29.6 | 34.6 |
| 37,000 ft | 41.7 | 43.5 | 43.9 | 43.6 | 44.7 | 43.9 | 43.8 | 39.8 | 37.3 | 35.7 | 33.6 | 39.3 |
| 39,000 ft | 46.7 | 48.7 | 49.1 | 48.9 | 50.1 | 49.1 | 49.1 | 44.5 | 41.6 | 39.9 | 37.4 | 43.9 |
| 41,000 ft | 51.4 | 53.7 | 54.2 | 53.9 | 55.3 | 54.2 | 54.1 | 48.9 | 45.7 | 43.8 | 41 | 48.3 |
The return flight: LHR → SIN
LHR → SIN receives 0.0308 mSv at 35,000 ft, 11% less than SIN → LHR, over about 12 h 3 min in the air against 13 h 23 min. The return is 1 h 20 min shorter: its track runs with the prevailing westerly winds at cruise altitude. Cosmic radiation builds up with every minute aloft, so the longer direction collects more of it along the same path.
What 34.6 µSv compares with
| Compared with | Its dose | This flight is |
|---|---|---|
| Chest X-Ray | 0.1 mSv | about a third of a chest X-ray |
| Dental X-Ray | 0.005 mSv | about 6.9 dental X-rays |
| Background Radiation (Daily) | 0.008 mSv | about 4.3 days of natural background radiation |
| Mammogram | 0.4 mSv | about 9% of a mammogram |
| Head CT Scan | 2 mSv | about 2% of a head CT scan |
| Eating a Banana | 0.0001 mSv | about 346 bananas |
The comparison values are the ones the FlightDose app uses.
Why your flight will differ
- Altitude. Flown at 31,000 ft instead, the same flight would receive 0.0256 mSv, 26% less than at 35,000 ft; at 41,000 ft it would receive 0.0483 mSv, 40% more. Same route, same time in the air, same month: only the air overhead changes.
- Time in the air. Every extra 30 minutes on this route adds about 1.3 µSv. Headwinds, holding and routing change it by tens of minutes on a long flight.
- The month. The sun's 11-year cycle swings this route's dose by about 33% between quiet and active years.
- The track. Airlines fly tracks that bend with the jet stream, not the exact great circle; a track further from the equator collects more.
- Solar storms. A rare solar radiation storm can add to the dose for hours; CARI-7's monthly figures don't include one.
FlightDose calculates your exact flight.
Your date, your altitude, your time in the air, with live space weather, and a running total against the limits that matter to you.