Cosmic radiation dose calculator
Estimate the galactic cosmic ray (GCR) dose you receive on any flight leg — route, cruise altitude, and solar activity taken into account. Free, no account required.
Solar activity (NOAA G-scale)
Each level uses an independently fitted polynomial — small inconsistencies between adjacent levels are expected from the published measurement data.
Reference context (approximate)
- •Annual natural background — approximately 2.4 mSv/year global average from all sources (terrestrial, radon, medical, cosmic). GCR is only one component. (UNSCEAR 2008.)
- •EU occupational limit for aircrew — Directive 2013/59/Euratom (Art. 9) sets a 20 mSv/year limit, averaged over 5 consecutive years. Aircraft operators must manage crew exposure and apply enhanced oversight above 6 mSv/year (Category A). Below 6 mSv, Category B provisions apply.
What you are measuring
Galactic cosmic rays (GCR)
Galactic cosmic rays are high-energy atomic nuclei — mostly protons — accelerated by supernovae and other energetic events within our galaxy, outside the solar system. They bombard Earth continuously from all directions at close to the speed of light.
Why altitude matters
The atmosphere provides shielding. At sea level, roughly 1,000 g/cm² of air absorbs most of the primary particles. At cruise altitude (FL350–FL410, approximately 10–12 km), that shielding reduces to about 200–300 g/cm², and the effective dose rate rises sharply.
Why latitude matters
Earth's magnetic field deflects lower-energy cosmic ray particles. Near the poles, field lines run vertically and offer less protection — the GCR flux is higher. Near the equator, horizontal field lines provide maximum shielding. A flight from Dublin to Edinburgh receives a higher dose rate than a similar-length flight between Mediterranean cities.
Solar activity and geomagnetic storms
The NOAA G-scale measures geomagnetic storm intensity. A stronger storm weakens Earth's magnetic shielding, lowering the cutoff rigidity and allowing more GCR particles to reach aviation altitudes — so G3 generally produces a higher GCR dose rate than G0. In practice the relationship is not perfectly monotonic: each G level is fitted independently from sparse measurement data, and the model covers the 2013–2018 period of moderate-to-declining solar activity.
A separate real effect — the Forbush decrease — occurs when a coronal mass ejection sweeps past Earth and temporarily suppresses GCR flux. This is a distinct transient phenomenon and is not what the G selector models.
An active Sun can also emit Solar Particle Events (SPEs) that dramatically increase doses independently of the GCR channel. This calculator does not model SPEs.
Limitations
- GCR only. Solar particle events are not modelled. During an SPE, actual in-flight doses can be orders of magnitude higher.
- Constant cruise altitude. The model integrates dose minute by minute along the great-circle path, but uses the cruise FL you specify for the entire cruise phase. Actual climb and descent altitudes are approximated with a fixed profile.
- Polynomial range. The NAIRAS polynomial coefficients are calibrated for 9–14 km altitude. Results at other altitudes use documented approximations.
- Conservative bias. This engine implements the 2018 published polynomial representation of the NAIRAS model (Tobiska et al.). Published intercomparison studies have found NAIRAS to produce higher readings than measurement-validated models. We retain this conservative bias deliberately rather than applying an unvalidated correction factor.
- Indicative estimate only. This is not a regulatory dosimetry record. For official crew dose monitoring, use a certified programme: CARI-7A (FAA), EPCARD, SIEVERT, or your national authority tool.
Engine based on: Tobiska, W. K. et al. (2018). Analytical representations for characterising the global aviation radiation environment based on model and measurement databases. Space Weather, 16, 1523–1538. DOI: 10.1029/2018SW001843