Becquerel (Bq) is the SI unit of radioactivity, equal to one disintegration per second. Curie (Ci) is the traditional unit, equal to 3.7×10¹⁰ disintegrations per second (originally the activity of 1 gram of radium-226). The conversion is: 1 Ci = 37 GBq (gigabecquerels). Becquerel is used worldwide in scientific contexts, while Curie is still commonly used in the United States, particularly in nuclear medicine and environmental monitoring.
Radioactivity Converter
Convert between Becquerel, Curie, Rutherford, and other radioactivity units with scientific precision.
Conversion Formula
1 Becquerel = 1 disintegration per second
Common Conversions
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Radiation Dose Reference Scale
Understanding radiation exposure levels in everyday life. All values in millisieverts (mSv) per year unless noted.
Safe (<1 mSv)
Low (1-10 mSv)
Moderate (10-100 mSv)
High (100-1000 mSv)
Extreme (>1000 mSv)
Banana (eating one)
0.0001 mSv
Dental X-ray
0.005 mSv
Chest X-ray
0.1 mSv
Annual background radiation
2.4 mSv
CT scan (abdomen)
10 mSv
Annual occupational limit
20-50 mSv
Radiation sickness threshold
1,000 mSv (acute)
Lethal dose (50% fatal)
4,000-5,000 mSv
How to Use This Radiation Converter
Our radiation converter is engineered for precision using standards from NIST, ICRP, and IAEA. Follow these steps for accurate conversions.
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Select Category Choose from 8 radiation categories using the sidebar or mobile drawer.
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Choose Source Unit Pick the unit you want to convert from (e.g., Becquerel, Sievert).
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Choose Target Unit Select the unit you want to convert to (e.g., Curie, Rem).
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Enter Value Type your radiation value — the result appears instantly.
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View Formula The exact conversion formula is displayed for verification.
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Check Safety Scale Use the reference scale to understand exposure levels.
Why Professionals Choose ASLI FORM
Built with precision engineering using international standards from NIST, ICRP, IAEA, and BIPM for maximum accuracy.
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NIST/ICRP Standards Conversion factors from official metrology and radiological institutes.
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Scientific Precision Results accurate to 10 significant digits for professional use.
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Instant Results Real-time conversion as you type — no buttons to click.
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Works Offline All calculations run locally. Perfect for field work and labs.
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Frequently Asked Questions
Gray (Gy) measures absorbed dose — the physical energy deposited per kilogram of tissue (1 Gy = 1 J/kg). Sievert (Sv) measures equivalent dose — the biological effect of that radiation, accounting for radiation type through radiation weighting factors. For gamma and beta radiation, 1 Gy ≈ 1 Sv. For alpha radiation, 1 Gy = 20 Sv due to higher biological damage. Sievert is used for radiation protection purposes.
The average person receives about 2.4 mSv per year from natural background radiation (cosmic rays, radon, terrestrial sources). The recommended public limit is 1 mSv/year above background. Occupational limits are typically 20-50 mSv/year. A chest X-ray delivers about 0.1 mSv, while a CT scan delivers 5-10 mSv. Acute radiation sickness begins around 1,000 mSv (1 Sv) received at once. The lethal dose (50% fatal within 30 days) is approximately 4,000-5,000 mSv.
Rad (radiation absorbed dose) measures physical energy absorbed — 1 rad = 0.01 Gy. Rem (roentgen equivalent man) measures biological effect — 1 rem = 0.01 Sv. For most common radiation (gamma, X-rays, beta), 1 rad ≈ 1 rem. For alpha radiation, 1 rad = 20 rem due to higher biological damage. Rad and Rem are traditional US units; Gray and Sievert are the modern SI equivalents.
Radon is typically measured in Becquerels per cubic meter (Bq/m³) internationally, or picocuries per liter (pCi/L) in the United States. The conversion is: 1 pCi/L = 37 Bq/m³. The WHO recommends action below 100 Bq/m³ (2.7 pCi/L), while the US EPA recommends action below 148 Bq/m³ (4 pCi/L). Radon is the second leading cause of lung cancer after smoking.
Exposure (measured in Roentgen or C/kg) quantifies the ionization produced in air by X-rays or gamma rays. Absorbed dose (Gray or Rad) measures energy deposited in any material. Equivalent dose (Sievert or Rem) accounts for biological effectiveness of different radiation types. Effective dose (also Sievert) further accounts for tissue sensitivity. Think of it as: Exposure → what's in the air, Dose → what hits you, Effect → what it does to you.
Our converter uses scientifically-verified conversion factors from NIST, ICRP, and IAEA standards. However, for medical dosimetry, radiation therapy planning, or regulatory compliance, always use certified medical-grade equipment and consult qualified health physicists. Our tool is designed for educational, reference, and general calculation purposes. Medical applications require specialized calibration and quality assurance.
- Alpha (α): Heavy, positively charged particles. Stopped by paper. High biological damage if ingested.
- Beta (β): Light electrons/positrons. Stopped by aluminum. Moderate penetration.
- Gamma (γ): High-energy photons. Requires lead or concrete shielding. Deep penetration.
- X-rays: Similar to gamma but produced electronically. Used in medical imaging.
- Neutron: Uncharged particles. Requires hydrogen-rich shielding (water, concrete). Very penetrating.
Background radiation is the ionizing radiation present in the environment from natural sources. The global average is about 2.4 mSv per year, composed of:
- Radon gas: ~1.2 mSv (50% of total) — from uranium decay in soil
- Terrestrial: ~0.5 mSv — from radioactive elements in Earth's crust
- Cosmic rays: ~0.4 mSv — from space, increases with altitude
- Internal: ~0.3 mSv — from radioactive isotopes in our bodies (like K-40)
ALARA stands for "As Low As Reasonably Achievable". It's the fundamental principle of radiation protection, requiring that all radiation exposures be kept as low as reasonably achievable, considering economic and social factors. ALARA is implemented through three key methods:
- Time: Minimize exposure time
- Distance: Maximize distance from source (inverse square law)
- Shielding: Use appropriate barriers (lead, concrete, water)
Half-life is the time required for half of the radioactive atoms in a sample to decay. After each half-life, the activity decreases by 50%. For example:
- Iodine-131: 8 days (used in medical treatment)
- Cobalt-60: 5.27 years (industrial radiography)
- Cesium-137: 30 years (industrial gauges)
- Plutonium-239: 24,100 years (nuclear weapons)
- Uranium-238: 4.5 billion years (natural uranium)
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