Convert Radiation Dose Units Online Convert between sieverts, millisieverts, microsieverts, rem, millirem, grays, and rads.

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Radiation Converter

Convert between sieverts, millisieverts, microsieverts, rem, millirem, grays, and rads.

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What Is Radiation Converter?

A radiation converter translates between units measuring ionizing radiation dose. The sievert (Sv) is the SI unit of dose equivalent (biological effect), while the gray (Gy) measures absorbed dose (physical energy). The rem (roentgen equivalent man) and rad are older units still widely used in the US. For gamma and beta radiation, 1 Sv = 1 Gy numerically (quality factor Q = 1), but for alpha particles and neutrons the relationship differs. This converter handles standard unit conversions and is essential for health physics, nuclear medicine, radiation safety, and environmental monitoring.

Why Use Radiation Converter?

Covers both dose equivalent (Sv/rem) and absorbed dose (Gy/rad).
Includes micro and millisievert for everyday dose measurements.
Essential for radiation safety professionals.
Results update instantly as you type with no page reloads.

Common Use Cases

Health Physics

Convert occupational dose measurements between SI and legacy units.

Nuclear Medicine

Translate patient dose values between sieverts and rem for clinical records.

Radiation Safety

Compare dose limits expressed in different unit systems.

Environmental Monitoring

Express background radiation readings in µSv or mrem for field reports.

Technical Guide

Radiation dose units:

Dose Equivalent (biological effect):
• 1 Sv = 1,000 mSv = 1,000,000 µSv
• 1 Sv = 100 rem
• 1 mSv = 100 mrem = 0.1 rem

Absorbed Dose (physical energy):
• 1 Gy = 100 rad
• 1 Gy = 1 J/kg of tissue

Relationship: Sv = Gy × Q (quality factor)
• For gamma/beta: Q = 1, so 1 Sv = 1 Gy
• For alpha: Q = 20, so 1 Gy of alpha = 20 Sv
• For neutrons: Q = 5-20 depending on energy

Typical doses:
• Natural background: ~2.4 mSv/year (240 mrem/year)
• Chest X-ray: ~0.02 mSv (2 mrem)
• CT scan: 2-10 mSv
• US occupational limit: 50 mSv/year (5 rem/year)
• Acute lethal dose: ~4-5 Sv

Tips & Best Practices

1
1 Sv = 100 rem. 1 mSv = 100 mrem. These are the key conversion factors.
2
For gamma/beta radiation: Sv and Gy are numerically equal.
3
Average natural background radiation is about 2.4 mSv (240 mrem) per year.
4
A single chest X-ray delivers about 0.02 mSv — very low.

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Frequently Asked Questions

Q How do I convert rem to millisieverts?

Multiply rem by 10. For example, 5 rem = 50 mSv.

Q What is the difference between gray and sievert?

Gray (Gy) measures the physical energy absorbed (1 Gy = 1 J/kg). Sievert (Sv) accounts for biological effect using a quality factor: Sv = Gy × Q.

Q What is a safe radiation dose?

Background radiation is about 2.4 mSv/year. Occupational limits are typically 20-50 mSv/year. There is no perfectly "safe" dose, but low doses have negligible measurable health effects.

Q Are sievert and gray the same for X-rays?

Yes, for X-rays (gamma radiation), the quality factor Q = 1, so 1 Sv = 1 Gy numerically.

Q How much radiation is a CT scan?

A typical CT scan delivers 2-10 mSv depending on the body area and protocol.

About This Tool

Radiation Converter is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.