Cosmic radiation on flights from New York (JFK) to London (LHR)

Reverse: London → New York

A flight from John F. Kennedy International Airport to London Heathrow Airport at 35,000 ft, about 6 h 18 min in the air, receives about 0.0265 mSv (26.5 µSv) of cosmic radiation: about a quarter 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
26.5 µSv0.0265 mSv
Time in the air
6 h 18 minestimated
Dose rate
4.2 µSv/haverage, 35,000 ft
Chest X‑rays
0.27at 0.1 mSv each

Key facts: JFK → LHR

Dose, standard flight0.0265 mSv (26.5 µSv)
Time in the air6 h 18 min, estimated from distance and prevailing winds
Cruise altitude35,000 ft
Average dose rate4.2 µSv/h
Great-circle distance5,540 km (3,442 mi)
Furthest from the equator53.7°N
Solar conditionsAugust 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, 6 h 18 min in the air (climb 25 min, cruise 336 min, descent 17 min), effective dose per ICRP Publication 103. How it's calculated.

JFKLHR
Great-circle route, shaded from 3.9 µSv/h to 4.4 µSv/h. Shading is modelled from the monthly dose-rate grid; totals are CARI-7.

How the sun changes the dose on JFK → LHR

The sun's 11-year cycle moves this number. With the same 6 h 18 min at 35,000 ft, the flight would have received 0.0338 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0204 mSv in January 2026, near solar maximum: 66% more at the quiet end. In August 2026 it is 0.0265 mSv.

Dose for this flight at 35,000 ft, quarterly
0 µSv10 µSv20 µSv30 µSv40 µSv20162018202020222024202633.8 µSv20.4 µSv26.5 µSv
0 µSv10 µSv20 µSv30 µSv40 µSv20162020202433.8 µSv20.4 µSv26.5 µSv
The numbers behind the chart
MonthDoseDose
January 201629.4 µSv0.0294 mSv
April 201630.4 µSv0.0304 mSv
July 201630.2 µSv0.0302 mSv
October 201631.4 µSv0.0314 mSv
January 201731.8 µSv0.0318 mSv
April 201732.6 µSv0.0326 mSv
July 201732 µSv0.032 mSv
October 201731.6 µSv0.0316 mSv
January 201832.3 µSv0.0323 mSv
April 201833.2 µSv0.0332 mSv
July 201833 µSv0.033 mSv
October 201833.7 µSv0.0337 mSv
January 201932 µSv0.032 mSv
April 201933.6 µSv0.0336 mSv
July 201933.1 µSv0.0331 mSv
October 201933.6 µSv0.0336 mSv
January 202033.4 µSv0.0334 mSv
April 202033.8 µSv0.0338 mSv
July 202033.5 µSv0.0335 mSv
October 202033.5 µSv0.0335 mSv
January 202132.3 µSv0.0323 mSv
April 202133.6 µSv0.0336 mSv
July 202132.8 µSv0.0328 mSv
October 202132.9 µSv0.0329 mSv
January 202232.2 µSv0.0322 mSv
April 202231.8 µSv0.0318 mSv
July 202228.9 µSv0.0289 mSv
October 202229.9 µSv0.0299 mSv
January 202327.1 µSv0.0271 mSv
April 202327.4 µSv0.0274 mSv
July 202325.7 µSv0.0257 mSv
October 202325.9 µSv0.0259 mSv
January 202424.2 µSv0.0242 mSv
April 202425 µSv0.025 mSv
July 202425.2 µSv0.0252 mSv
October 202421.7 µSv0.0217 mSv
January 202522.6 µSv0.0226 mSv
April 202522.6 µSv0.0226 mSv
July 202522.3 µSv0.0223 mSv
October 202523 µSv0.023 mSv
January 202620.4 µSv0.0204 mSv
April 202623.4 µSv0.0234 mSv
July 202625.2 µSv0.0252 mSv
August 202626.5 µSv0.0265 mSv

How cruise altitude changes the dose

Flown at 31,000 ft instead, the same flight would receive 0.0192 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0388 mSv, 46% more. Same route, same time in the air, same month: only the air overhead changes.

Dose for this flight by cruise altitude, August 2026
  • 31,000 ft19.2 µSv
  • 33,000 ft22.7 µSv
  • 35,000 ft26.5 µSv
  • 37,000 ft30.5 µSv
  • 39,000 ft34.6 µSv
  • 41,000 ft38.8 µSv

Try it: change the altitude and the month

Every combination is its own CARI-7 run for JFK → LHR, with the same 6 h 18 min in the air. It is still a standard flight, not yours: the app calculates your exact flight.

Every combination as a table (µSv)
AltitudeJan 2016Jan 2017Jan 2018Jan 2019Jan 2020Jan 2021Jan 2022Jan 2023Jan 2024Jan 2025Jan 2026Aug 2026
31,000 ft21.222.823.122.923.923.223.119.617.616.414.919.2
33,000 ft25.227.127.527.328.527.527.423.220.819.417.622.7
35,000 ft29.431.832.33233.432.332.227.124.222.620.426.5
37,000 ft33.936.637.236.938.637.337.131.227.825.923.330.5
39,000 ft38.641.842.4424442.542.335.431.529.326.334.6
41,000 ft43.44747.847.449.747.847.739.635.232.629.338.8

The return flight: LHR → JFK

LHR → JFK receives 0.031 mSv at 35,000 ft, 17% more than JFK → LHR, over about 7 h 16 min in the air against 6 h 18 min. The return takes 58 min longer: its track runs against 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.

Dose for each direction, standard flight
  • JFK → LHR26.5 µSv
  • LHR → JFK31 µSv

Cosmic radiation on London → New York flights

What 26.5 µSv compares with

Compared withIts doseThis flight is
Chest X-Ray0.1 mSvabout a quarter of a chest X-ray
Dental X-Ray0.005 mSvabout 5.3 dental X-rays
Background Radiation (Daily)0.008 mSvabout 3.3 days of natural background radiation
Mammogram0.4 mSvabout 7% of a mammogram
Head CT Scan2 mSvabout 1% of a head CT scan
Eating a Banana0.0001 mSvabout 265 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 0.0192 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0388 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.

Download on the App Store Get it on Google Play

Other routes from JFK

All about John F. Kennedy International Airport

Other routes to LHR

Every published route

Questions people ask

All questions