Zeptosievert is 1e-21 sievert units.
Zeptosieverts to Rems Converter — zSv to rem
Convert Zeptosievert (zSv) to Rem (rem) using the exact conversion factor (1 zeptosievert = 1e-19 rem). See the formula, worked examples, conversion table, and common uses.
Zeptosieverts to Rems 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.
Rem is 0.01 sievert.
Result = input x 1e-21 / 0.01.
Equivalent Dose units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Zeptosieverts to Rems
Zeptosievert and Rem 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. Specifically: Zeptosievert is 1e-21 sievert units, and rem is 0.01 sievert.
Formula
rems = zeptosieverts × 1e-19
This factor comes from each unit's defined relationship to the category's base unit: 1 zeptosievert equals 1e-21 base units, and 1 rem equals 0.01 base units, so dividing one by the other gives the direct zeptosievert-to-rem factor of 1e-19.
Simple example
1 zSv × 1e-19 = 1e-19 rem
1 zeptosievert = 1e-19 rems.
Real-world example
10 zSv × 1e-19 = 1e-18 rem
10 zeptosieverts = 1e-18 rems.
Conversion table
| Zeptosievert (zSv) | Rem (rem) |
|---|---|
| 0.001 zSv | 1e-22 rem |
| 0.01 zSv | 1e-21 rem |
| 0.1 zSv | 1e-20 rem |
| 1 zSv | 1e-19 rem |
| 10 zSv | 1e-18 rem |
| 100 zSv | 1e-17 rem |
Reverse conversion: Rem to Zeptosievert
1e-19 rem × 1e+19 = 1 zSv
1e-19 rems = 1 zeptosievert.
zeptosieverts = rems × 1e+19
For a page dedicated to this direction, see Rem to Zeptosievert.
Understanding the Zeptosievert (zSv)
Zeptosievert is 1e-21 sievert units.
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
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 rems are in 1 zeptosievert?
1 zeptosievert equals 1e-19 rems, using the exact defined conversion factor rather than an estimate.
How do I convert zeptosievert to rem?
Multiply the zeptosievert value by 1e-19. The converter above does this instantly to whatever precision you set.
How do I convert rem back to zeptosievert?
Use the reverse factor: 1 rem equals 1e+19 zeptosieverts. You can also use the swap control in the converter above to flip the direction instantly.
What is a zeptosievert?
Zeptosievert (zSv) is a unit of radiation.
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.
Is the zeptosievert to rem 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.