This sievert to rem converter changes equivalent or effective dose between sieverts, millisieverts, microsieverts, rem, millirem and microrem. The factors are exact: 1 Sv = 100 rem, so 1 mSv = 100 mrem. The same factors convert a dose rate, so 1 µSv/h = 0.1 mrem/h.
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How to use the sievert to rem converter
- Enter the dose or rate, for example 0.25 from a survey meter in µSv/h.
- In the sievert to rem converter, choose its unit and the target unit, such as µSv to mrem.
- Read the sievert to rem converter result: 0.25 µSv/h = 0.025 mrem/h.
For mSv to rem, divide by 10. For rem to mSv, multiply by 10. Keep the time unit (per hour or per year) unchanged on both sides.
What is equivalent radiation dose?
Equivalent dose weights absorbed dose for the biological effect of the radiation type. The SI unit is the sievert (Sv); the US also uses the rem, where 1 Sv = 100 rem and 1 mSv = 100 mrem.
Conversion formula
The sievert to rem converter stores every unit as a multiple of the base unit, the sievert (Sv). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in sieverts.
Common equivalent radiation dose conversions
| From | To | 1 unit equals |
|---|---|---|
| sievert (Sv) | rem (rem) | 100 rem |
| rem (rem) | sievert (Sv) | 0.01 Sv |
| millisievert (mSv) | millirem (mrem) | 100 mrem |
| microsievert (µSv) | millirem (mrem) | 0.1 mrem |
Sievert to rem converter worked example
Convert 25 millisieverts to millirem:
- Factor of mSv = 0.001 Sv
- Factor of mrem = 1 × 10−5 Sv
- 25 × 0.001 ÷ 1 × 10−5 = 2,500 mrem
Equivalent radiation dose unit reference
| Unit | Symbol | Group | Equals (Sv) |
|---|---|---|---|
| Sievert | Sv | SI | 1 |
| Millisievert | mSv | SI | 0.001 |
| Microsievert | µSv | SI | 1 × 10−6 |
| Rem | rem | Traditional US | 0.01 |
| Millirem | mrem | Traditional US | 1 × 10−5 |
| Microrem | µrem | Traditional US | 1 × 10−8 |
Reverse factors for each equivalent radiation dose unit
The sievert to rem converter reference table gives each unit in sieverts. To go the other way, divide by that factor; the list below does the division for you.
- Millisievert (mSv), SI: 1 mSv = 0.001 Sv, so 1 Sv = 1,000 mSv.
- Microsievert (µSv), SI: 1 µSv = 1 × 10−6 Sv, so 1 Sv = 1,000,000 µSv.
- Rem (rem), Traditional US: 1 rem = 0.01 Sv, so 1 Sv = 100 rem.
- Millirem (mrem), Traditional US: 1 mrem = 1 × 10−5 Sv, so 1 Sv = 100,000 mrem.
- Microrem (µrem), Traditional US: 1 µrem = 1 × 10−8 Sv, so 1 Sv = 1 × 108 µrem.
US dose limits in mSv and rem
The US NRC rules in 10 CFR Part 20 are written in rem. In SI units:
| Limit or reference (per year) | rem | mSv | Average µSv/h over 8,760 h |
|---|---|---|---|
| Occupational total effective dose limit, 10 CFR 20.1201 | 5 | 50 | 5.708 |
| Member of the public limit, 10 CFR 20.1301 | 0.1 | 1 | 0.114 |
| Average US exposure from all sources (NRC) | 0.62 | 6.2 | 0.708 |
The last column shows each annual figure as a steady hourly rate; real exposure is not uniform.
From dose rate to dose
Dose equals dose rate times time. A worker in a 20 µSv/h area for 3 hours receives 60 µSv, or 6 mrem. Sieverts measure biological effect; the physical energy deposited is measured in grays. Sv = Gy × radiation weighting factor, which is 1 for gamma rays and X-rays. Use the absorbed dose converter for grays and rads and the radioactivity converter for source activity.
Everyday doses
Typical medical and background doses help put numbers in context. A chest X-ray gives about 0.1 mSv, which the sievert to rem converter shows as 10 mrem. The average US resident receives about 6.2 mSv a year from all sources, about 620 mrem. A CT scan of the abdomen is often around 8 to 10 mSv. One sievert is exactly 100 rem.
US regulations still use rem, so annual limits are often written both ways. The occupational limit of 50 mSv a year is 5 rem, and the public limit of 1 mSv is 100 mrem. Hospitals and nuclear plants in the US report badge doses in mrem, while most other countries use mSv. Converting is just a factor of 100.
Related converters and calculators
Related radiation tools:
- Absorbed dose converter: Gy and rad
- Radiation exposure converter: R and C/kg
- Radioactivity converter: Bq and Ci
- Half-life calculator: decay over time
- Scientific notation calculator: powers of ten
Sources
US NRC: 10 CFR Part 20, Standards for Protection Against Radiation; US NRC: Doses in our daily lives; NIST Special Publication 811, Appendix B.
Questions about this calculator
How many rem are in a sievert?
100 rem = 1 Sv exactly.
How do I convert mSv to rem?
Divide by 10. For example, 50 mSv = 5 rem.
How do I convert µSv/h to mrem/h?
Divide by 10. For example, 2 µSv/h = 0.2 mrem/h.
What is the US public dose limit?
0.1 rem (1 mSv) per year under 10 CFR 20.1301.
Is a sievert the same as a gray?
For gamma rays and X-rays the numbers match, but Sv includes a weighting for biological effect and Gy does not.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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