Rem is 0.01 sievert.
Rems to Megasieverts Converter — rem to MSv
Convert Rem (rem) to Megasievert (MSv) using the exact conversion factor (1 rem = 1e-8 megasievert). See the formula, worked examples, conversion table, and common uses.
Rems to Megasieverts 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.
Megasievert is 1000000 sievert units.
Result = input x 0.01 / 1e+6.
Equivalent Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Rems to Megasieverts
Rem and Megasievert 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
megasieverts = rems × 1e-8
This factor comes from each unit's defined relationship to the category's base unit: 1 rem equals 0.01 base units, and 1 megasievert equals 1000000 base units, so dividing one by the other gives the direct rem-to-megasievert factor of 1e-8.
Simple example
1 rem × 1e-8 = 1e-8 MSv
1 rem = 1e-8 megasieverts.
Real-world example
10 rem × 1e-8 = 1e-7 MSv
10 rems = 1e-7 megasieverts.
Conversion table
| Rem (rem) | Megasievert (MSv) |
|---|---|
| 0.001 rem | 1e-11 MSv |
| 0.01 rem | 1e-10 MSv |
| 0.1 rem | 1e-9 MSv |
| 1 rem | 1e-8 MSv |
| 10 rem | 1e-7 MSv |
| 100 rem | 0.000001 MSv |
Reverse conversion: Megasievert to Rem
1e-8 MSv × 100000000 = 1 rem
1e-8 megasieverts = 1 rem.
rems = megasieverts × 100000000
For a page dedicated to this direction, see Megasievert 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 Megasievert (MSv)
Megasievert is 1000000 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 megasieverts are in 1 rem?
1 rem equals 1e-8 megasieverts, using the exact defined conversion factor rather than an estimate.
How do I convert rem to megasievert?
Multiply the rem value by 1e-8. The converter above does this instantly to whatever precision you set.
How do I convert megasievert back to rem?
Use the reverse factor: 1 megasievert equals 100,000,000 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 megasievert?
Megasievert (MSv) is a unit of radiation.
Is the rem to megasievert 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