Are sieverts and curies the same type of measurement?

No. Curies (Ci) measure radioactivity — the rate of nuclear decay (how many atoms disintegrate per second). Sieverts (Sv) measure biological dose — the health effect of radiation on tissue. Converting between them is only an approximation and requires a dose conversion factor that varies by radiation type and nuclide.

What dose conversion factors does this tool use?

Representative effective dose coefficients for ingestion: alpha ≈ 2.0 × 10⁻⁷ Sv/Bq, beta ≈ 1.0 × 10⁻⁸ Sv/Bq, gamma/X-ray ≈ 3.0 × 10⁻⁹ Sv/Bq. These are order-of-magnitude estimates. Actual values depend on the specific nuclide, exposure pathway, and age group. Consult ICRP Publication 119 for precise coefficients.

What is 1 curie in becquerels?

1 curie (Ci) = 3.7 × 10¹⁰ becquerels (Bq). The curie was originally defined as the activity of 1 gram of radium-226. The becquerel is the SI unit: 1 Bq = 1 disintegration per second.

Can I use this for regulatory or compliance purposes?

No. This tool is educational. Regulatory dose-to-activity calculations require nuclide-specific coefficients, pathway modeling, and sign-off by a licensed health physicist. Use ICRP, NCRP, or NRC data tables for any compliance purpose.

Why does alpha radiation give a much lower curie estimate for the same dose?

Alpha particles have a radiation weighting factor of 20, which inflates their dose per becquerel. Because the dose factor is large, dividing a given dose by that factor yields a smaller becquerel (and therefore curie) value. In other words, a tiny amount of alpha-emitting activity can deliver a large dose — especially when inhaled or ingested.

Sieverts to Curies Converter

Name: Sieverts to Curies Converter
Availability: InStock
Author: Nham Vu

Convert radiation dose in sieverts (Sv) back to approximate activity in curies (Ci) using a selected radiation-type dose factor — shown step by step.

Input Dose

Dose value

Input unit

Radiation type

Enter a dose value and select a radiation type, then click Convert.

Note: Dose factors are representative effective dose coefficients for ingestion. Actual values depend on the specific nuclide and exposure pathway. For regulatory calculations, consult ICRP Publication 119 or a licensed health physicist.

Summary

Convert radiation dose in sieverts (Sv) back to approximate activity in curies (Ci) using a selected radiation-type dose factor — shown step by step.

How it works

Enter a dose value in sieverts, millisieverts, or microsieverts.
Select the radiation type (alpha, beta, gamma, or X-ray) to load the representative dose conversion factor.
The tool divides your dose by the factor to convert sieverts back to becquerels (Bq).
It then divides the becquerel value by 3.7 × 10¹⁰ to get curies (Ci).
Results appear in curies, millicuries, and microcuries, with each step shown.

Use cases

Working backwards from a dose estimate to approximate source activity in a research or lab setting.
Checking consistency between dose records (Sv) and legacy source data still expressed in curies.
Teaching or studying the inverse Sv → Bq → Ci conversion chain in nuclear physics or radiobiology.
Cross-referencing historical nuclear dosimetry data with modern activity measurements.
Estimating the approximate activity of a source that produced a known dose for educational purposes.
Understanding how dose factors affect activity estimates across different radiation types.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu