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Convert between all radiation units including Sieverts, rem, Gray, rad, and roentgen
Note: *N/A indicates incompatible unit types. Equivalent dose (Sv, rem) and absorbed dose (Gy, rad) measure different quantities and cannot be directly converted without knowing the radiation type and quality factor. For gamma/X-rays, the numeric values are approximately equal (1 Gy ≈ 1 Sv).
| Exposure Type | Dose (mSv) | Dose (rem) |
|---|---|---|
| Eating one banana (K-40) | 0.0001 mSv | 0.00001 rem |
| Dental X-ray | 0.005 mSv | 0.0005 rem |
| Chest X-ray | 0.1 mSv | 0.01 rem |
| Round-trip flight (NY to LA) | 0.04 mSv | 0.004 rem |
| Mammogram | 0.4 mSv | 0.04 rem |
| Head CT scan | 2 mSv | 0.2 rem |
| Annual background radiation (U.S.) | 3.1 mSv | 0.31 rem |
| Chest CT scan | 7 mSv | 0.7 rem |
| Whole-body CT scan | 10 mSv | 1 rem |
| Public annual dose limit | 1 mSv/year | 0.1 rem/year |
| Occupational annual limit | 50 mSv/year | 5 rem/year |
| Astronaut (6 months on ISS) | 80 mSv | 8 rem |
| Lowest dose causing symptoms | 500 mSv | 50 rem |
| LD50/60 (lethal to 50%) | 4,000-5,000 mSv | 400-500 rem |
Measures the biological effect of radiation on human tissue. Takes into account the type of radiation and its relative biological effectiveness. Used for radiation protection and risk assessment. Sievert (Sv) is the SI unit; rem is the traditional unit (1 Sv = 100 rem).
Measures the physical amount of radiation energy absorbed per unit mass of material. Does not account for biological effectiveness. Used in radiation therapy, dosimetry calibration, and material testing. Gray (Gy) is the SI unit; rad is the traditional unit (1 Gy = 100 rad).
Roentgen (R) measures ionization in air caused by X-rays or gamma rays. It's an older unit being phased out in favor of absorbed dose (Gy) or air kerma. Approximately 1 R ≈ 8.77 mGy in air, but conversion to tissue dose requires additional factors.
For gamma rays and X-rays, the numerical values of Gy and Sv are approximately equal (quality factor = 1), so 1 Gy ≈ 1 Sv. However, for alpha particles, 1 Gy = 20 Sv due to higher biological effectiveness.
THIS CONVERTER IS FOR EDUCATIONAL AND REFERENCE PURPOSES ONLY
Never use this calculator for actual radiation safety decisions. Radiation measurements must be performed using calibrated, professional-grade dosimetry equipment by trained personnel.
Do not attempt to measure radiation exposure without proper equipment including:
If you suspect radiation exposure:
All radiation work must comply with: ALARA principles, NRC regulations (10 CFR), state radiation control programs, institutional safety committees, and professional standards (NCRP, ICRP, AAPM).
Sieverts measure equivalent dose (biological effect) while Gray measures absorbed dose (physical energy). They represent different quantities. For gamma and X-rays, the numbers are approximately equal (1 Gy ≈ 1 Sv), but for other radiation types like alpha particles or neutrons, you need to apply quality factors: 1 Gy of alphas = 20 Sv.
Millisievert (mSv) = 0.001 Sv, while microsievert (µSv) = 0.000001 Sv. Thus, 1 mSv = 1,000 µSv. Typical environmental and medical doses are in the mSv or µSv range, while occupational limits are in mSv, and Sv is reserved for very high doses.
No, natural background radiation (average 3.1 mSv/year in the U.S.) is normal and unavoidable. It comes from cosmic rays, radon gas, rocks, soil, and even our own bodies (potassium-40). Radiation protection focuses on minimizing additional exposure beyond background levels.
Medical imaging should only be performed when medically necessary, following ALARA principles. A single CT scan (7-10 mSv) is generally considered safe, but unnecessary repeated imaging should be avoided. The benefit of correct diagnosis almost always outweighs the small risk from properly justified medical imaging.
The quality factor accounts for the biological effectiveness of different radiation types. X-rays and gamma rays: Q=1; Beta particles: Q=1; Neutrons: Q=5-20 (energy-dependent); Alpha particles: Q=20. To convert absorbed dose (Gy) to equivalent dose (Sv): multiply by Q.
Yes, radiation dose is tracked cumulatively for regulatory purposes. However, the body has repair mechanisms, so low doses over time are less harmful than the same total dose received acutely. Cancer risk is considered proportional to cumulative lifetime dose, though threshold effects exist for acute radiation syndrome.
Geiger counters typically display either counts per minute (CPM), µSv/h (microsieverts per hour), or mR/h (milliroentgen per hour) depending on the model. Consumer models often show µSv/h, while professional instruments may allow selection between multiple unit systems.
The mathematical conversions are exact according to standard definitions. However, real-world dose assessment involves uncertainties in measurement, calibration, geometry, and tissue composition. This converter provides precise unit conversion but cannot account for measurement uncertainties in actual dosimetry.