How much radiation do you get on a flight? Numbers for 14 routes

By LogAloft's calculation, a New York to London flight delivered about 30 microsieverts (µSv) of cosmic radiation under the solar conditions of July 2026. That is about a third of a two-view chest X-ray. The figure moves a good deal with the route, the cruising altitude, the time aloft and the state of the Sun.

The numbers

We ran 14 routes through LogAloft's dose model, the same one the app uses for every logged flight. Each run assumes a great-circle path at FL350 with 2,000-foot step climbs on the long legs, a typical air time and the solar conditions of July 2026. Real flights differ a little, because wind-optimized routings, North Atlantic tracks and the levels ATC assigns all shift the result.

The chest X-ray column uses 0.1 mSv (100 µSv) for a standard two-view exam, the figure in the Radiology reference catalog by Mettler and colleagues; a single front view is about a fifth of that.

Compare Los Angeles–Sydney with New York–Tokyo. Both are long, but the Sydney flight spends most of its time at low latitudes and picks up about half the dose per hour. Dallas–São Paulo and London–Johannesburg tell the same story. Length matters, but latitude sets how fast the dose accumulates.

What changes the dose

The FAA lists four factors in AC 120-61B: time in the air, altitude, latitude and solar activity.

Latitude first. Earth's magnetic field turns many cosmic rays away near the equator and far fewer near the poles. In our model at FL350 over the North Atlantic, the dose rate rises from about 1.8 µSv an hour near the equator to 2.7 at 35°N, 3.9 at 45°N and about 4.5 from 55°N up, where it levels off. The FAA puts the rate over the polar regions at about twice the rate over the geomagnetic equator at the same altitude.

Altitude next. Less air above you means less shielding. Flown level the whole way, New York–London comes out at about 19 µSv at FL310, 27 at FL350 and 35 at FL390 in our model, or roughly 15 to 20% more for every 2,000 feet at these levels.

Time is the simplest of the four. Dose accumulates hour by hour at cruise, while climb and descent add little, which is why a one-hour hop barely registers.

The Sun is the factor that surprises people. Galactic cosmic rays, the source of nearly all of a normal flight's dose, peak near solar minimum, when the Sun's magnetic field does the least to keep them out of the inner solar system (NOAA SWPC). With everything else held the same, our model gives New York–London about 41 µSv at the October 2009 solar minimum and about 24 µSv in January 2026, a month of high solar activity. By July 2026 activity had eased somewhat, and the same flight was back up to about 30 µSv, the figure in the table above. New York–Tokyo moves from about 89 µSv to about 52 µSv over the same swing. NASA and NOAA announced in October 2024 that the Sun had reached the maximum phase of its cycle (NASA), so doses on the same routes should creep up over the next several years as it heads toward the next minimum.

Solar storms are a separate and occasional effect, covered in Solar storms and your flight.

Passengers: what it adds up to

For occasional travelers the numbers are small. The Health Physics Society puts the dose at about 0.01 mSv for every 1,600 km flown and says it should be of no concern for someone taking a few trips a year. Ten round trips between New York and London come to about 0.6 mSv in our model. That is still below 1 mSv, the yearly public dose limit the ICRP recommends for planned exposures (ICRP 103). The limit doesn't legally apply to passengers, but it is a useful reference point.

If you are pregnant and fly often, ask your doctor. For crew members, the FAA recommends keeping the dose to the unborn child to no more than 0.5 mSv in any month (AC 120-61B).

Pilots: what a year looks like

Crew fly the same flights, many times over. New York–London works out to about 4 µSv per block hour at mid-2026 conditions. A pilot flying 750 block hours a year on routes like it would collect about 3 mSv a year now, and about 4 mSv at solar minimum. That is in line with the figures from the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR): its 2000 report, cited in AC 120-61B, ranked aircrew as the fourth most exposed group of workers at an average of 3 mSv a year, and its latest survey puts the worldwide average for 2010 to 2014 at 2.7 mSv (UNSCEAR 2020/2021, Annex D). The occupational limit recommended by the ICRP, and by the FAA for crew, is 20 mSv a year averaged over five years, with no more than 50 mSv in any single year.

In the US, no rule requires an airline to track your dose. In the EU, operators must assess crew dose once it is liable to exceed 1 mSv a year (Directive 2013/59/Euratom, Article 35). What the August 2026 Harvard study on aircrew cancer found, and what it can't show, is the subject of Pilots and the new cancer study.

How we worked this out

LogAloft follows the method of CARI-7A, the program the FAA's Civil Aerospace Medical Institute publishes for calculating galactic cosmic radiation dose along a flight path. On reference flights, our model agrees with CARI-7A to within about 1%. Solar conditions for each month come from the FAA's published monthly heliocentric potential, or from a neutron-monitor nowcast for months the FAA has not yet published. Like CARI-7A's flight calculations, these numbers cover galactic cosmic radiation, not solar particle events.

This is information, not medical advice.

What LogAloft does with this

Look up any flight by number or by its two airports, and LogAloft shows the dose in µSv and in chest X-rays, with a map of where along the route it was received. Try New York to London or Chicago to Hong Kong. In the logbook, each flight gets a dose, and the year's total is shown against the 1 mSv reference.

Sources

1. AC 120-61B, In-Flight Radiation Exposure, FAA, November 21, 2014
2. CARI-7 and CARI-7A, FAA Civil Aerospace Medical Institute
3. Galactic Cosmic Rays, NOAA Space Weather Prediction Center
4. Council Directive 2013/59/Euratom, EUR-Lex, December 5, 2013
5. Evaluation of occupational exposure to ionizing radiation (UNSCEAR 2020/2021 Report, Annex D), UNSCEAR, 2022
6. Dose limits (ICRP Publication 103), ICRPaedia, ICRP
7. Effective doses in radiology and diagnostic nuclear medicine: a catalog (Mettler et al.), Radiology, 2008
8. NASA, NOAA: Sun Reaches Maximum Phase in 11-Year Solar Cycle, NASA, October 15, 2024
9. Ask the Experts: radiation from airplane travel, Health Physics Society