Rem is 0.01 sievert.
Rems to Millisieverts Converter — rem to mSv
Convert Rem (rem) to Millisievert (mSv) using the exact conversion factor (1 rem = 10 millisievert). See the formula, worked examples, conversion table, and common uses.
Rems to Millisieverts converter
Converter
Radiation Converter
Convert radioactivity, absorbed dose, and equivalent dose units by compatible radiation family.
Context values
Some unit families need one extra value for a physically accurate result.
Millisievert is 0.001 sievert units.
Result = input x 0.01 / 0.001.
Equivalent Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Rems to Millisieverts
Rem and Millisievert both belong to the radiation-measurement family, though radiation quantities fall into genuinely distinct categories: absorbed dose (gray, rad) measures energy deposited in matter, equivalent dose (sievert, rem) weights that for biological harm, and activity (becquerel, curie) measures how often a radioactive source decays — this page only converts between units of the same kind. Rem is most often used for us occupational radiation dose limits and monitoring.
Formula
millisieverts = rems × 10
This factor comes from each unit's defined relationship to the category's base unit: 1 rem equals 0.01 base units, and 1 millisievert equals 0.001 base units, so dividing one by the other gives the direct rem-to-millisievert factor of 10.
Simple example
1 rem × 10 = 10 mSv
1 rem = 10 millisieverts.
Real-world example
10 rem × 10 = 100 mSv
10 rems = 100 millisieverts.
Conversion table
| Rem (rem) | Millisievert (mSv) |
|---|---|
| 0.001 rem | 0.01 mSv |
| 0.01 rem | 0.1 mSv |
| 0.1 rem | 1 mSv |
| 1 rem | 10 mSv |
| 10 rem | 100 mSv |
| 100 rem | 1,000 mSv |
Reverse conversion: Millisievert to Rem
10 mSv × 0.1 = 1 rem
10 millisieverts = 1 rem.
rems = millisieverts × 0.1
For a page dedicated to this direction, see Millisievert to Rem.
Understanding the Rem
Rem (rem) measures equivalent radiation dose. 'Roentgen equivalent man' — the US customary unit of equivalent radiation dose, fixed at exactly 0.01 sievert. It is classified as a non-SI unit, still common in the US.
Where it's used: Still widely used in the United States alongside the SI sievert
Rem vs. sievert. Both measure equivalent radiation dose; the sievert is the modern SI unit while the rem is the older US customary unit, related by 1 sievert = 100 rem exactly.
Uses of the Rem today
- US occupational radiation dose limits and monitoring
- US nuclear regulatory reporting
- US medical radiation dose records
Understanding the Millisievert (mSv)
Millisievert is 0.001 sievert units.
Rem — sources
- US NRC (Nuclear Regulatory Commission) — glossary — Definition and continued regulatory use of the rem in the United States.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many millisieverts are in 1 rem?
1 rem equals 10 millisieverts, using the exact defined conversion factor rather than an estimate.
How do I convert rem to millisievert?
Multiply the rem value by 10. The converter above does this instantly to whatever precision you set.
How do I convert millisievert back to rem?
Use the reverse factor: 1 millisievert equals 0.1 rems. You can also use the swap control in the converter above to flip the direction instantly.
What is a rem?
Rem (rem) measures equivalent radiation dose. 'Roentgen equivalent man' — the US customary unit of equivalent radiation dose, fixed at exactly 0.01 sievert. It is classified as a non-SI unit, still common in the US.
What is a millisievert?
Millisievert (mSv) is a unit of radiation.
Is the rem to millisievert conversion exact?
Yes. 'Roentgen equivalent man' — the US customary unit of equivalent radiation dose, fixed at exactly 0.01 sievert. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between rem vs. sievert?
Both measure equivalent radiation dose; the sievert is the modern SI unit while the rem is the older US customary unit, related by 1 sievert = 100 rem exactly.
Where is the rem still used today?
Still widely used in the United States alongside the SI sievert