Flight Radiation Calculator

Estimate the cosmic-ray radiation dose you pick up on a flight from cruising altitude, route latitude, and solar activity, plus what that adds up to over a year of flying.

Quick Facts

Typical dose rate
About 3-5 microsieverts per hour at cruising altitude
Cosmic-ray intensity roughly doubles for every 1,500 m (about 4,900 ft) of altitude gained, and polar routes run roughly double the dose rate of equatorial routes at the same altitude.

Your Results

Calculated
Dose this flight
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Effective dose, single flight
Dose rate at cruise
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Microsieverts per hour, this route
Annual dose (these flights)
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Flights per year x dose per flight
Chest X-ray equivalent
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Using about 100 microsieverts per chest X-ray

Ready

Set flight duration, altitude, route latitude, and solar phase, then press Calculate.

How the flight radiation estimate works

Every flight exposes passengers and crew to galactic cosmic radiation — high-energy particles from outside the solar system that the atmosphere normally blocks at ground level. At cruising altitude there is far less air overhead to absorb that radiation, so dose rates are much higher than on the ground. This calculator estimates effective dose as flight duration (hours) multiplied by a dose rate (microsieverts per hour) that depends on cruising altitude, route latitude, and where the sun is in its roughly 11-year solar cycle.

The dose-rate model

The dose rate is built from a reference value of about 4 microsieverts per hour at 35,000 feet, mid-latitude, average solar conditions — a figure consistent with published aviation dosimetry guidance, which commonly cites 3 to 5 microsieverts per hour for typical commercial cruise altitudes. From that reference point, three factors adjust the rate:

  • Altitude: dose rate roughly doubles for every 1,500 m (about 4,900 ft) gained, since each extra 1,500 m removes roughly half the shielding air mass above the aircraft.
  • Route latitude: Earth's magnetic field deflects more cosmic radiation near the equator than near the poles. Equatorial routes run at roughly half the mid-latitude dose rate, while polar routes run at roughly 1.9x the mid-latitude rate.
  • Solar activity: counterintuitively, cosmic-ray dose is lower during solar maximum — a more active sun's stronger solar wind deflects more galactic cosmic radiation — and higher during solar minimum.

Multiplying the resulting dose rate by flight duration gives the effective dose for one flight. Multiplying that by how many similar flights are taken per year gives an annual estimate, which this calculator compares to the roughly 100-microsievert dose of a chest X-ray and to the roughly 3,000-microsievert average annual natural background dose in the United States.

Reading the result

A single coast-to-coast flight typically adds somewhere in the range of 15 to 40 microsieverts — a small fraction of annual background exposure for an occasional traveler. Frequent flyers and aircrew who log hundreds of hours a year can accumulate several thousand microsieverts annually, which is why aviation authorities in several countries apply the same occupational monitoring framework used for other radiation workers to aircrew, with a common reference dose constraint of about 20,000 microsieverts (20 millisieverts) per year.

Assumptions and limits

This is a simplified estimate, not a replacement for detailed dosimetry tools such as the FAA's CARI model or EPA flight radiation guidance, which account for the exact flight path, real-time solar activity, and minute-by-minute altitude profile. Actual dose varies with the specific route flown, current solar conditions (including rare solar particle events), and altitude changes during climb and descent.

Frequently Asked Questions

How much cosmic radiation do I get on a flight?
Commercial flights typically add about 3 to 5 microsieverts per hour of cosmic radiation at cruising altitude, roughly the equivalent of a chest X-ray (about 100 microsieverts) every 20 to 30 hours in the air. This calculator estimates dose as flight duration multiplied by a dose rate that depends on altitude, route latitude, and solar activity.
Why does radiation increase with altitude?
The atmosphere shields the ground from galactic cosmic rays. As altitude increases there is less air overhead to absorb that radiation, so intensity rises quickly, roughly doubling for every 1,500 meters (about 4,900 feet) gained, which is why dose rates at typical cruising altitudes of 30,000 to 40,000 feet are far higher than at sea level.
Are polar flights more radioactive than equatorial ones?
Yes. Earth's magnetic field deflects more cosmic radiation near the equator than near the poles, so a route over high latitudes can receive roughly twice the dose rate of a similar flight closer to the equator at the same altitude, which is why this calculator includes a route latitude setting.
Should frequent flyers or pilots worry about this exposure?
Occasional flying adds only a small fraction of typical annual background radiation exposure, about 3,000 microsieverts a year on average in the US. Aircrew who fly hundreds of hours a year accumulate enough cosmic-ray dose that aviation authorities monitor it using the same occupational framework applied to other radiation workers, with a common reference constraint of about 20,000 microsieverts (20 millisieverts) per year.

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