Cosmic radiation on flights from London (LHR) to New York (JFK)
A flight from London Heathrow Airport to John F. Kennedy International Airport at 35,000 ft, about 7 h 16 min in the air, receives about 0.031 mSv (31 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
- 31 µSv0.031 mSv
- Time in the air
- 7 h 16 minestimated
- Dose rate
- 4.3 µSv/haverage, 35,000 ft
- Chest X‑rays
- 0.31at 0.1 mSv each
Key facts: LHR → JFK
| Dose, standard flight | 0.031 mSv (31 µSv) |
|---|---|
| Time in the air | 7 h 16 min, estimated from distance and prevailing winds |
| Cruise altitude | 35,000 ft |
| Average dose rate | 4.3 µSv/h |
| Great-circle distance | 5,540 km (3,442 mi) |
| Furthest from the equator | 53.7°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, 7 h 16 min in the air (climb 25 min, cruise 394 min, descent 17 min), effective dose per ICRP Publication 103. How it's calculated.
How the sun changes the dose on LHR → JFK
The sun's 11-year cycle moves this number. With the same 7 h 16 min at 35,000 ft, the flight would have received 0.0394 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0238 mSv in January 2026, near solar maximum: 66% more at the quiet end. In August 2026 it is 0.031 mSv.
The numbers behind the chart
| Month | Dose | Dose |
|---|---|---|
| January 2016 | 34.4 µSv | 0.0344 mSv |
| April 2016 | 35.4 µSv | 0.0354 mSv |
| July 2016 | 35.3 µSv | 0.0353 mSv |
| October 2016 | 36.6 µSv | 0.0366 mSv |
| January 2017 | 37.1 µSv | 0.0371 mSv |
| April 2017 | 38.1 µSv | 0.0381 mSv |
| July 2017 | 37.3 µSv | 0.0373 mSv |
| October 2017 | 36.9 µSv | 0.0369 mSv |
| January 2018 | 37.7 µSv | 0.0377 mSv |
| April 2018 | 38.7 µSv | 0.0387 mSv |
| July 2018 | 38.5 µSv | 0.0385 mSv |
| October 2018 | 39.4 µSv | 0.0394 mSv |
| January 2019 | 37.3 µSv | 0.0373 mSv |
| April 2019 | 39.3 µSv | 0.0393 mSv |
| July 2019 | 38.7 µSv | 0.0387 mSv |
| October 2019 | 39.3 µSv | 0.0393 mSv |
| January 2020 | 39 µSv | 0.039 mSv |
| April 2020 | 39.4 µSv | 0.0394 mSv |
| July 2020 | 39.1 µSv | 0.0391 mSv |
| October 2020 | 39.1 µSv | 0.0391 mSv |
| January 2021 | 37.7 µSv | 0.0377 mSv |
| April 2021 | 39.3 µSv | 0.0393 mSv |
| July 2021 | 38.3 µSv | 0.0383 mSv |
| October 2021 | 38.4 µSv | 0.0384 mSv |
| January 2022 | 37.5 µSv | 0.0376 mSv |
| April 2022 | 37.1 µSv | 0.0371 mSv |
| July 2022 | 33.8 µSv | 0.0338 mSv |
| October 2022 | 35 µSv | 0.035 mSv |
| January 2023 | 31.6 µSv | 0.0316 mSv |
| April 2023 | 32 µSv | 0.032 mSv |
| July 2023 | 30 µSv | 0.03 mSv |
| October 2023 | 30.2 µSv | 0.0302 mSv |
| January 2024 | 28.3 µSv | 0.0283 mSv |
| April 2024 | 29.2 µSv | 0.0292 mSv |
| July 2024 | 29.5 µSv | 0.0295 mSv |
| October 2024 | 25.4 µSv | 0.0254 mSv |
| January 2025 | 26.3 µSv | 0.0263 mSv |
| April 2025 | 26.4 µSv | 0.0264 mSv |
| July 2025 | 26.1 µSv | 0.0261 mSv |
| October 2025 | 26.8 µSv | 0.0268 mSv |
| January 2026 | 23.8 µSv | 0.0238 mSv |
| April 2026 | 27.3 µSv | 0.0273 mSv |
| July 2026 | 29.5 µSv | 0.0295 mSv |
| August 2026 | 31 µSv | 0.031 mSv |
How cruise altitude changes the dose
Flown at 31,000 ft instead, the same flight would receive 0.0224 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0453 mSv, 46% 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 LHR → JFK, with the same 7 h 16 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 | 24.8 | 26.6 | 27 | 26.8 | 28 | 27 | 27 | 22.8 | 20.5 | 19.2 | 17.4 | 22.4 |
| 33,000 ft | 29.4 | 31.6 | 32.1 | 31.8 | 33.3 | 32.1 | 32 | 27.1 | 24.3 | 22.6 | 20.5 | 26.5 |
| 35,000 ft | 34.4 | 37.1 | 37.7 | 37.3 | 39 | 37.7 | 37.5 | 31.6 | 28.3 | 26.3 | 23.8 | 31 |
| 37,000 ft | 39.6 | 42.8 | 43.5 | 43.1 | 45.1 | 43.5 | 43.4 | 36.4 | 32.5 | 30.2 | 27.2 | 35.6 |
| 39,000 ft | 45 | 48.7 | 49.5 | 49.1 | 51.4 | 49.6 | 49.4 | 41.3 | 36.8 | 34.2 | 30.7 | 40.4 |
| 41,000 ft | 50.6 | 54.9 | 55.8 | 55.3 | 58 | 55.8 | 55.6 | 46.3 | 41.1 | 38.1 | 34.2 | 45.3 |
The return flight: JFK → LHR
JFK → LHR receives 0.0265 mSv at 35,000 ft, 14% less than LHR → JFK, over about 6 h 18 min in the air against 7 h 16 min. The return is 58 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 31 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 6.2 dental X-rays |
| Background Radiation (Daily) | 0.008 mSv | about 3.9 days of natural background radiation |
| Mammogram | 0.4 mSv | about 8% of a mammogram |
| Head CT Scan | 2 mSv | about 2% of a head CT scan |
| Eating a Banana | 0.0001 mSv | about 310 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 0.0224 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0453 mSv, 46% 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 2.1 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 66% 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.