Rem is 0.01 sievert.
Rems to Zettasieverts Converter — rem to ZSv
Convert Rem (rem) to Zettasievert (ZSv) using the exact conversion factor (1 rem = 1e-23 zettasievert). See the formula, worked examples, conversion table, and common uses.
Rems to Zettasieverts 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.
Zettasievert is 1e+21 sievert units.
Result = input x 0.01 / 1e+21.
Equivalent Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Rems to Zettasieverts
Rem and Zettasievert 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
zettasieverts = rems × 1e-23
This factor comes from each unit's defined relationship to the category's base unit: 1 rem equals 0.01 base units, and 1 zettasievert equals 1e+21 base units, so dividing one by the other gives the direct rem-to-zettasievert factor of 1e-23.
Simple example
1 rem × 1e-23 = 1e-23 ZSv
1 rem = 1e-23 zettasieverts.
Real-world example
10 rem × 1e-23 = 1e-22 ZSv
10 rems = 1e-22 zettasieverts.
Conversion table
| Rem (rem) | Zettasievert (ZSv) |
|---|---|
| 0.001 rem | 1e-26 ZSv |
| 0.01 rem | 1e-25 ZSv |
| 0.1 rem | 1e-24 ZSv |
| 1 rem | 1e-23 ZSv |
| 10 rem | 1e-22 ZSv |
| 100 rem | 1e-21 ZSv |
Reverse conversion: Zettasievert to Rem
1e-23 ZSv × 1e+23 = 1 rem
1e-23 zettasieverts = 1 rem.
rems = zettasieverts × 1e+23
For a page dedicated to this direction, see Zettasievert 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 Zettasievert (ZSv)
Zettasievert is 1e+21 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 zettasieverts are in 1 rem?
1 rem equals 1e-23 zettasieverts, using the exact defined conversion factor rather than an estimate.
How do I convert rem to zettasievert?
Multiply the rem value by 1e-23. The converter above does this instantly to whatever precision you set.
How do I convert zettasievert back to rem?
Use the reverse factor: 1 zettasievert equals 1e+23 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 zettasievert?
Zettasievert (ZSv) is a unit of radiation.
Is the rem to zettasievert 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