Radiation Dose Converter
Convert absorbed and equivalent dose between Sv and rem units.
What it does
Radiation dose uses two unit families. SI reports sieverts with milli and micro prefixes. US custom reports rem with millirem. Both measure the same biological effect for equivalent dose, only the scale differs.
The tool above converts among Sv, mSv, uSv, rem, and mrem. The defaults convert 100 mrem to mSv, so the page opens showing 1 mSv. Pick new units to update the result and the full list.
The link is exact by definition: 1 rem = 0.01 Sv, so 1 Sv = 100 rem. From there milli is 0.001 and micro is 0.000001 in each family. A chest CT near 7 mSv is 700 mrem on the same scale.
Use sieverts for reports, papers, and meters. Use rem where US rules or old instruments quote it. Keep absorbed dose in gray apart from equivalent dose in sieverts when radiation type matters, since weighting factors enter there.
This page shows the factors, one full hand checked example at 100 mrem, a reference table, and practice checks that run through the tool.
How to use
- Type the dose number, for example 100.
- Pick the starting unit in From unit, for example mrem.
- Pick the target unit in To unit, for example mSv.
- Read the main result with unit name.
- Scan the note line for the same dose in all five units.
- Check context: background is microsieverts, therapy is sieverts.
Formula
- Sv
- Sievert, SI unit. Base for math.
- rem
- US custom unit. 1 rem = 0.01 Sv.
- m, u
- Milli 0.001 and micro 0.000001 prefixes.
Factors are exact by unit definition. For X rays and gamma, 1 Sv counts near 1 Gy absorbed. For alpha and neutrons, quality factors change equivalent dose and need separate tables.
Worked example
Example: 100 mrem to mSv
A badge reads 100 millirem. Express in millisieverts.
- Write 100, from mrem, to mSv.
- Base: 100 x 0.00001 = 0.001 Sv.
- Target factor: 1 mSv = 0.001 Sv.
- Divide: 0.001 / 0.001 = 1 mSv.
- Cross check: 1 mSv is 100 mrem by the 100 to 1 rem rule.
- Siblings: 1000 uSv and 0.1 rem.
Reference table
| Unit | Sv per unit | Note |
|---|---|---|
| Sv | 1 | Base |
| mSv | 0.001 | Medical scans |
| uSv | 0.000001 | Background |
| rem | 0.01 | US custom |
| mrem | 0.00001 | Badges |
Limits
- Units only. No risk model here.
- Equivalent dose assumed. Absorbed gray needs radiation weighting first.
- Four decimals suit field work. Low background may need more.
- Regulatory limits depend on context and time span, not just units.
Common mistakes
- Reading mrem as mSv, off by 100 times.
- Mixing gray with sievert for alpha or neutron dose.
- Dropping micro vs milli by 1000 times.
- Adding doses from different weighting without factors.
- Quoting therapy sieverts as if background microsieverts.
Try it yourself
Quick checks. Answers sit tucked under each question.
2.5 Sv in rem?
2.5 / 0.01 = 250 rem.
500 mrem in mSv?
500 x 0.00001 / 0.001 = 5 mSv.
Questions
How many mSv in 100 mrem?
1 mSv.
Sv or rem?
SI uses Sv, US custom uses rem. 1 Sv is 100 rem.
What is background?
About a few mSv per year from natural sources, or a few hundred mrem.
Gray or sievert?
Gray is absorbed energy. Sievert weights by radiation type for effect.
Why five units?
Milli and micro span medical to background without long decimals.
Is this medical advice?
No. Units only. Dose guidance needs a qualified expert.