How this instrument works
Cosmic radiation reaches Earth constantly, and the atmosphere shields against most of it — but that shielding thins out with altitude, so exposure rises the higher you go. The effect is measurable even at modest elevations: background radiation from cosmic rays alone is meaningfully higher for someone living in a mile-high city than at sea level, and it rises further still at commercial airline cruising altitude, tens of thousands of feet higher again.
This calculator multiplies your flight duration by a dose rate you supply, defaulting to a mid-range estimate of 0.005 millisieverts per hour. Independently reported ranges for cruising-altitude cosmic-ray dose rate commonly span roughly 0.003 to 0.008 mSv/h depending on altitude, latitude, and solar activity — routes closer to the poles and at higher cruising altitudes sit toward the upper end, so adjust the rate if you know more about your specific route.
For scale, airline crew members — who fly far more hours than an occasional passenger — pick up an estimated 2.2 millisieverts of additional occupational radiation exposure per year on average from repeated high-altitude flying, nearly doubling their total annual radiation exposure compared to a ground-based job. This calculator estimates a single flight's contribution to that same kind of exposure, not a cumulative health risk assessment — it's an informational estimate, not medical guidance.
- Enter your flight duration in hours.
- Adjust the dose rate if you know your route's typical value — the default is a mid-range estimate within the commonly cited 0.003–0.008 mSv/h range.
- Read your estimated total dose in millisieverts.
- Read the same figure in microsieverts, the smaller unit often used for single-flight comparisons.
Worked example — a 10-hour long-haul flight
A 10-hour flight at the default mid-range dose rate of 0.005 mSv/h: 10 × 0.005 = 0.05 mSv, or equivalently 50 microsieverts.
For context, airline crew members accumulate an estimated 2.2 mSv of additional occupational exposure per year from repeated flying — a single 10-hour flight at this rate represents roughly 1/44th of that annual crew figure (2.2 ÷ 0.05 ≈ 44), which helps put an occasional traveler's single-flight exposure in perspective against someone flying professionally, day after day.
Questions
Is flight radiation a real health concern for an occasional traveler?
For someone flying occasionally, the additional dose from a handful of flights a year is small compared to typical annual background radiation exposure from all sources combined, and this calculator is meant as an informational estimate rather than a health risk assessment. It isn't medical guidance — for concerns about cumulative radiation exposure from frequent flying, consult a radiation health professional rather than relying on this estimate alone.
Why does radiation exposure increase at cruising altitude?
The atmosphere absorbs and deflects a large share of incoming cosmic radiation, and that shielding effect weakens the higher you go — there's simply less atmosphere left above you to absorb it. The effect is already measurable at a mile-high elevation on the ground and becomes considerably more pronounced at the 30,000-40,000 foot cruising altitudes commercial flights operate at.
Where does the 0.003–0.008 mSv/h dose-rate range come from?
It reflects independently reported estimates for cosmic-ray dose rate at typical commercial cruising altitude, which varies with the plane's actual altitude, the flight's latitude (routes nearer the poles receive more cosmic radiation due to Earth's magnetic field geometry), and solar activity at the time. This calculator defaults to a mid-range figure within that span and leaves it fully adjustable.
How much radiation do airline crew members accumulate in a year?
Airline crews flying long-distance, high-altitude routes regularly pick up an estimated additional occupational dose of around 2.2 millisieverts per year from cosmic radiation, nearly doubling their total annual ionizing radiation exposure compared to typical ground-based background levels — a reflection of how much more flight time crew members log compared to occasional passengers.
Does flying a polar route expose me to more radiation than other routes?
Generally, yes — cosmic radiation intensity increases toward Earth's magnetic poles because the planet's magnetic field deflects less of it there compared to equatorial regions, so long polar routes (common on some transcontinental flights) tend to sit toward the higher end of the commonly cited dose-rate range.