Radiation Dose Converter

Convert between radiation dose units — sieverts, rem, grays, rad, and their sub-multiples — for dosimetry.

Quantity

Dose type

From

Value

Unit

Result

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Enter a value to convert

1 mSv = 100 mrem.

Current value in every unit of this family — click any card to set as target

Reference: Both Families Relative to Their Base Unit

Unit	Symbol	In base	1 base unit =

1 Sv = 100 remequivalent dose, SI ↔ conventional 1 Gy = 100 radabsorbed dose, SI ↔ conventional 1 mSv = 100 mremsub-multiple shortcut 1 Sv = 1,000 mSv = 1,000,000 µSvSI sub-multiples

Common Real-World Doses (Equivalent Dose)

Source	mSv	mrem

4 min read 3 steps 7 terms 3 examples 6 FAQs rem = Sv × 100

Radiation dose is reported in two different unit systems — SI units (sievert, gray) used internationally, and conventional units (rem, rad) still common in US regulatory and clinical settings.

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Walk-through

How to Use This Calculator

3 steps

Choose the dose quantity

Pick Equivalent dose (Sv / rem) for biological-effect measurements like medical imaging and radiation-worker exposure limits, or Absorbed dose (Gy / rad) for the raw physical energy deposited by radiation. These two families are not interconvertible with each other.

Enter your value and pick From/To units

Type the number you want to convert, then choose the unit it's currently in (From) and the unit you want it in (To). Within the Equivalent dose family you can pick from Sv, mSv, µSv, rem, and mrem; within Absorbed dose you can pick from Gy and rad. The result updates instantly.

Read the converted result

The hero result shows your value converted into the target unit. The All Units panel below shows the same value expressed in every unit of the active family at once, and the Reference tab lists common real-world doses for context.

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Reference

Formula & Methodology

2 formulas

Equivalent dose: sievert ↔ rem

rem = Sv × 100

The sievert (Sv) is the SI unit of equivalent dose; the rem is the older conventional (CGS) unit still used in some US contexts, notably occupational dose limits. 1 sievert equals exactly 100 rem, so 1 millisievert (mSv) equals exactly 100 millirem (mrem).

Absorbed dose: gray ↔ rad

rad = Gy × 100

The gray (Gy) is the SI unit of absorbed dose — the physical energy deposited per unit mass (1 Gy = 1 joule/kg). The rad is the older conventional unit. 1 gray equals exactly 100 rad, the same ×100 relationship as the equivalent-dose family.

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Glossary

Key Terms Explained

7 terms

Sievert (Sv) The SI unit of equivalent dose, used to quantify the biological effect of radiation exposure on human tissue. It accounts for the type of radiation, not just the raw energy deposited. Regulatory dose limits (occupational, medical) are typically expressed in millisieverts (mSv).

Rem The conventional (non-SI) unit of equivalent dose, still widely used in the United States, especially by the NRC and OSHA for occupational exposure limits. 1 sievert = 100 rem, so 1 mSv = 100 mrem.

Gray (Gy) The SI unit of absorbed dose, defined as one joule of radiation energy deposited per kilogram of matter (1 Gy = 1 J/kg). Unlike the sievert, the gray measures raw physical energy transfer and does not weight for biological effect.

Rad The conventional (non-SI) unit of absorbed dose. 1 gray equals 100 rad — the same fixed ×100 relationship that connects sievert to rem in the equivalent-dose family.

Equivalent dose A measure of radiation exposure that accounts for how harmful a given type of radiation is to biological tissue, not just how much energy it deposits. Equivalent dose is what's used for medical imaging doses and occupational exposure limits, and is measured in sieverts or rem.

Absorbed dose The raw amount of radiation energy deposited per unit mass of material, regardless of the biological effect that energy causes. Absorbed dose is measured in grays or rad, and for X-rays and gamma rays it is numerically close to (though conceptually distinct from) equivalent dose.

Dosimetry The measurement and calculation of radiation dose absorbed by the human body or other matter, used in medical physics, radiation protection, and nuclear safety to track and limit exposure.

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Scenarios

Real-World Examples

3 worked examples

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Radiology technician

Converting a chest X-ray dose from sieverts to rem

Quantity Equivalent dose Value 0.1 mSv

0.1 mSv converts to 10 mrem — a typical single chest X-ray dose, useful when comparing US-reported rem figures against SI mSv figures from international literature.

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Medical physicist

Converting an absorbed radiotherapy dose from gray to rad

Quantity Absorbed dose Value 2 Gy

2 Gy converts to 200 rad — a typical single radiotherapy treatment fraction. Note this is absorbed dose (physical energy), not the equivalent dose used for whole-body exposure limits.

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Radiation safety officer

Checking an annual occupational exposure against the mSv limit

Quantity Equivalent dose Value 5000 mrem

5,000 mrem converts to 50 mSv — the US annual occupational equivalent-dose limit for radiation workers, expressed in the SI unit used by international standards bodies.

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Deep Dive

Understanding the Radiation Dose Converter

4 chapters · 4 min read

Radiation dose is reported in two different unit systems — SI units (sievert, gray) used internationally, and conventional units (rem, rad) still common in US regulatory and clinical settings. This converter moves between them instantly, while keeping equivalent dose and absorbed dose as two separate, non-interchangeable quantities.

How the Radiation Dose Converter works

The calculator uses a fixed ×100 relationship within each dose family: 1 sievert (Sv) equals exactly 100 rem, and 1 gray (Gy) equals exactly 100 rad. These conversion factors are defined by international agreement (via the International Commission on Radiation Units and Measurements), not measured or approximated. Sub-multiples — millisievert (mSv), microsievert (µSv), and millirem (mrem) — follow standard SI/decimal scaling from their base unit.

Why equivalent dose and absorbed dose stay separate

Equivalent dose (Sv/rem) and absorbed dose (Gy/rad) measure conceptually different things: absorbed dose is the raw physical energy deposited per kilogram of tissue, while equivalent dose weights that energy by how biologically damaging the specific radiation type is. For X-rays and gamma rays the numeric values happen to be close (a radiation weighting factor of 1), but for alpha particles or neutrons the equivalent dose can be many times higher than the absorbed dose for the same physical energy. Because the relationship between the two families depends on radiation type and isn't a fixed constant, this calculator does not offer a Sv ↔ Gy conversion — converting between them requires knowing the specific radiation weighting factor for your scenario.

Inputs and what they mean

Start by choosing which family you need — Equivalent dose for medical imaging doses, occupational limits, and radiation protection reporting, or Absorbed dose for physics and radiotherapy energy-deposition figures. Then enter your value and select the From and To units within that family. The All Units panel shows your value expressed in every unit of the active family simultaneously, which is useful when you need to report the same figure in both SI and conventional units.

Limits and edge cases

This calculator performs unit conversion only — it does not calculate dose from exposure time, source activity, or shielding, and it cannot convert between equivalent and absorbed dose without a radiation-specific weighting factor that this tool doesn't ask for. For dose limit compliance, occupational safety decisions, or medical treatment planning, always verify figures against the applicable regulatory standard (e.g. NRC, ICRP) or consult a qualified radiation safety officer or medical physicist rather than relying solely on this conversion.

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Questions

Frequently Asked Questions

6 questions

How do I convert sieverts to rem?+

Multiply the value in sieverts by 100 to get rem. For example, 0.05 Sv × 100 = 5 rem. The same ×100 factor applies to the sub-multiples: 1 mSv = 100 mrem.

How do I convert grays to rad?+

Multiply the value in grays by 100 to get rad. For example, 2 Gy × 100 = 200 rad. This is the absorbed-dose family, kept separate from equivalent dose (Sv/rem).

What's the difference between sievert (Sv) and gray (Gy)?+

Gray measures absorbed dose — the raw physical energy deposited per kilogram of tissue. Sievert measures equivalent dose — that same energy weighted by how biologically damaging the specific type of radiation is. For X-rays and gamma rays the two are numerically similar, but for alpha particles or neutrons they can differ by a large factor.

What is a millisievert (mSv)?+

A millisievert is one-thousandth of a sievert (1 Sv = 1,000 mSv). Most everyday radiation exposures — medical imaging, background radiation, air travel — are reported in mSv because a full sievert is a very large dose.

How much radiation dose is a typical chest X-ray?+

A single chest X-ray delivers approximately 0.1 mSv (10 mrem) of equivalent dose — roughly the same as about 10 days of natural background radiation exposure.

Which unit is the SI base unit — sievert/gray or rem/rad?+

Sievert and gray are the SI (International System of Units) base units for equivalent and absorbed dose respectively. Rem and rad are the older conventional (CGS) units, still in common use in the United States for occupational and regulatory reporting, but superseded internationally by Sv and Gy.

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Radiation Dose Converter

Equivalent Dose vs. Absorbed Dose

How to Use This Calculator

Choose the dose quantity

Enter your value and pick From/To units

Read the converted result

Formula & Methodology

Key Terms Explained

Real-World Examples

Radiology technician

Medical physicist

Radiation safety officer

Understanding the Radiation Dose Converter

How the Radiation Dose Converter works

Why equivalent dose and absorbed dose stay separate

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

Radiation Dose Converter

Equivalent Dose vs. Absorbed Dose

How to Use This Calculator

Choose the dose quantity

Enter your value and pick From/To units

Read the converted result

Formula & Methodology

Key Terms Explained

Real-World Examples

Understanding the Radiation Dose Converter

How the Radiation Dose Converter works

Why equivalent dose and absorbed dose stay separate

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

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