Cosmic radiation on flights from London (LHR) to Singapore (SIN)

Reverse: Singapore → London

A flight from London Heathrow Airport to Singapore Changi Airport at 35,000 ft, about 12 h 3 min in the air, receives about 0.0308 mSv (30.8 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
30.8 µSv0.0308 mSv
Time in the air
12 h 3 minestimated
Dose rate
2.6 µSv/haverage, 35,000 ft
Chest X‑rays
0.31at 0.1 mSv each

Key facts: LHR → SIN

Dose, standard flight0.0308 mSv (30.8 µSv)
Time in the air12 h 3 min, estimated from distance and prevailing winds
Cruise altitude35,000 ft
Average dose rate2.6 µSv/h
Great-circle distance10,882 km (6,762 mi)
Furthest from the equator52.5°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, 12 h 3 min in the air (climb 25 min, cruise 681 min, descent 17 min), effective dose per ICRP Publication 103. How it's calculated.

LHRSIN
Great-circle route, shaded from 1.4 µSv/h to 4.0 µSv/h. Shading is modelled from the monthly dose-rate grid; totals are CARI-7.

How the sun changes the dose on LHR → SIN

The sun's 11-year cycle moves this number. With the same 12 h 3 min at 35,000 ft, the flight would have received 0.0352 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0265 mSv in January 2026, near solar maximum: 33% more at the quiet end. In August 2026 it is 0.0308 mSv.

Dose for this flight at 35,000 ft, quarterly
0 µSv10 µSv20 µSv30 µSv40 µSv20162018202020222024202635.2 µSv26.5 µSv30.8 µSv
0 µSv10 µSv20 µSv30 µSv40 µSv20162020202435.2 µSv26.5 µSv30.8 µSv
The numbers behind the chart
MonthDoseDose
January 201632.7 µSv0.0327 mSv
April 201633.3 µSv0.0333 mSv
July 201633.2 µSv0.0332 mSv
October 201633.8 µSv0.0338 mSv
January 201734.1 µSv0.0341 mSv
April 201734.6 µSv0.0346 mSv
July 201734.2 µSv0.0342 mSv
October 201734 µSv0.034 mSv
January 201834.4 µSv0.0344 mSv
April 201834.9 µSv0.0349 mSv
July 201834.8 µSv0.0348 mSv
October 201835.2 µSv0.0352 mSv
January 201934.2 µSv0.0342 mSv
April 201935.1 µSv0.0351 mSv
July 201934.8 µSv0.0348 mSv
October 201935.1 µSv0.0351 mSv
January 202035 µSv0.035 mSv
April 202035.2 µSv0.0352 mSv
July 202035 µSv0.035 mSv
October 202035 µSv0.035 mSv
January 202134.4 µSv0.0344 mSv
April 202135.1 µSv0.0351 mSv
July 202134.6 µSv0.0347 mSv
October 202134.7 µSv0.0347 mSv
January 202234.3 µSv0.0343 mSv
April 202234.1 µSv0.0341 mSv
July 202232.4 µSv0.0324 mSv
October 202233 µSv0.033 mSv
January 202331.2 µSv0.0312 mSv
April 202331.4 µSv0.0314 mSv
July 202330.3 µSv0.0303 mSv
October 202330.4 µSv0.0304 mSv
January 202429.3 µSv0.0293 mSv
April 202429.8 µSv0.0298 mSv
July 202430 µSv0.03 mSv
October 202427.5 µSv0.0275 mSv
January 202528.1 µSv0.0281 mSv
April 202528.2 µSv0.0282 mSv
July 202527.9 µSv0.0279 mSv
October 202528.4 µSv0.0284 mSv
January 202626.5 µSv0.0265 mSv
April 202628.7 µSv0.0287 mSv
July 202630 µSv0.03 mSv
August 202630.8 µSv0.0308 mSv

How cruise altitude changes the dose

Flown at 31,000 ft instead, the same flight would receive 0.0228 mSv, 26% less than at 35,000 ft; at 41,000 ft it would receive 0.0431 mSv, 40% 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 ft22.8 µSv
  • 33,000 ft26.8 µSv
  • 35,000 ft30.8 µSv
  • 37,000 ft35 µSv
  • 39,000 ft39.2 µSv
  • 41,000 ft43.1 µSv

Try it: change the altitude and the month

Every combination is its own CARI-7 run for LHR → SIN, with the same 12 h 3 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 ft24.225.125.425.225.825.425.323.121.720.919.722.8
33,000 ft28.429.529.829.630.329.829.727.125.424.42326.8
35,000 ft32.734.134.434.23534.434.331.229.328.126.530.8
37,000 ft37.238.739.138.939.839.13935.533.231.93035
39,000 ft41.643.443.843.644.643.843.739.637.135.633.439.2
41,000 ft45.847.948.34849.348.348.243.640.839.136.643.1

The return flight: SIN → LHR

SIN → LHR receives 0.0346 mSv at 35,000 ft, 12% more than LHR → SIN, over about 13 h 23 min in the air against 12 h 3 min. The return takes 1 h 20 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
  • LHR → SIN30.8 µSv
  • SIN → LHR34.6 µSv

Cosmic radiation on Singapore → London flights

What 30.8 µSv compares with

Compared withIts doseThis flight is
Chest X-Ray0.1 mSvabout a third of a chest X-ray
Dental X-Ray0.005 mSvabout 6.2 dental X-rays
Background Radiation (Daily)0.008 mSvabout 3.9 days of natural background radiation
Mammogram0.4 mSvabout 8% of a mammogram
Head CT Scan2 mSvabout 2% of a head CT scan
Eating a Banana0.0001 mSvabout 309 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 0.0228 mSv, 26% less than at 35,000 ft; at 41,000 ft it would receive 0.0431 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.

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