Radiation Dose Converter

Convert between sievert, gray, rem, rad, becquerel, and curie — across dose, absorbed dose, and activity, for radiology and safety.

Radiation Dose

Sievert, Gray, Becquerel, Curie

From

Result

1000

1 Sv = 1000 mSv

Popular conversions

What Is a Radiation Dose Converter?

A radiation converter translates radiation quantities between units — sieverts to rem, grays to rads, becquerels to curies. The crucial thing is that 'radiation' covers several different quantities: absorbed dose (energy deposited, gray/rad), equivalent dose (biological effect, sievert/rem), and activity (decays per second, becquerel/curie). They are not interchangeable, and this tool keeps them straight within each kind.

This converter routes through SI units within each quantity. The sievert-to-rem and gray-to-rad conversions are a clean factor of 100, while the becquerel-to-curie conversion uses 3.7 × 10¹⁰. Because radiation safety, medical imaging, and nuclear work mix old (rem, rad, curie) and new (sievert, gray, becquerel) units, accurate conversion matters for dose limits and safety.

This is one category of the full Unit Converter — pair it with our percentage calculator or scientific calculator for related everyday maths.

How Radiation Conversion Works

Three distinct quantities

Absorbed dose (gray/rad), equivalent dose (sievert/rem), and activity (becquerel/curie) measure different things. Convert only within the same quantity.

Sievert ↔ rem is ×100

1 sievert = 100 rem, and 1 gray = 100 rad. The SI units replaced the older ones with a clean factor of 100.

Becquerel ↔ curie

Activity: 1 curie = 3.7 × 10¹⁰ becquerel (decays per second). The becquerel is tiny, so curies and gigabecquerels are common.

Dose vs activity differ fundamentally

Activity is how much a source decays; dose is the effect on what absorbs it. You can't convert becquerels into sieverts without more information.

Core Radiation Conversion Factors

Convert within a quantity. Sievert/gray use ×100; activity uses the curie factor.

Sievert → rem

× 100

One sievert is 100 rem (equivalent dose). 1 mSv = 100 mrem.

Gray → rad

× 100

One gray is 100 rad (absorbed dose, energy per mass).

Curie → becquerel

× 3.7 × 10¹⁰

One curie is 37 billion becquerels — decays per second of activity.

How to Use the Radiation Converter

1
Identify the quantity
Decide whether you have equivalent dose (Sv/rem), absorbed dose (Gy/rad), or activity (Bq/Ci) — they don't convert across types.
2
Enter the value
Type the radiation figure you want to convert — a dose reading, an exposure record, a source activity.
3
Choose 'from' and 'to' units
Pick the matching units within the same quantity, then swap if needed.
4
Read the equivalent
The all-units table shows the value across the related units (e.g. Sv, mSv, rem) at once.

Key Radiation Concepts

Equivalent dose (sievert)

Absorbed dose weighted by radiation type and biological effect, in sieverts (Sv) or rem. Used for dose limits and risk — 1 Sv = 100 rem.

Absorbed dose (gray)

Energy deposited per unit mass, in grays (Gy) or rad. One gray is one joule per kilogram; 1 Gy = 100 rad.

Activity (becquerel)

How fast a source decays, in becquerels (one decay per second) or curies. 1 Ci = 3.7 × 10¹⁰ Bq — a curie is a lot of activity.

Quantities don't cross

Activity (Bq), absorbed dose (Gy), and equivalent dose (Sv) are different. Converting between types needs physics, not a single factor.

Real-World Radiation Conversions

🩻

Medical imaging

A chest X-ray is about 0.1 mSv (10 mrem); a CT scan several mSv. Patient dose records convert between mSv and mrem.

✈️

Cosmic exposure

A transatlantic flight gives ~0.05 mSv (5 mrem). Aircrew dose monitoring uses sieverts and rem.

☢️

Occupational limits

Radiation workers are limited to ~20 mSv/year (2,000 mrem). Safety regulations span both unit systems.

🔬

Source activity

A lab source of 1 µCi is 37,000 Bq. Activity labels and licences mix curies and becquerels.

🌍

Background radiation

Natural background is ~2–3 mSv/year (200–300 mrem). The baseline every exposure is compared against.

⚛️

Cancer radiotherapy

Tumour treatment delivers absorbed doses of tens of grays (thousands of rad). Therapy planning works in grays.

Best Practices for Radiation Conversion

✓Convert only within a quantity. Sievert, gray, and becquerel measure different things. Never convert activity (Bq) directly into dose (Sv) — that needs exposure physics, not a factor.
✓Use ×100 for SI-to-old dose units. 1 Sv = 100 rem and 1 Gy = 100 rad. The clean factor of 100 makes dose conversion straightforward once the quantity is right.
✓Mind the prefixes. Doses are usually small (mSv, µSv); a slip from mSv to Sv overstates exposure 1,000-fold. Carry the prefix precisely.
✓Distinguish dose from dose rate. Sieverts are a total dose; sieverts per hour is a rate. Don't confuse a cumulative dose with an exposure rate.
✓Compare against background. Natural background is ~2–3 mSv/year. Putting a converted dose in that context makes its significance clear.

Common Radiation Conversion Mistakes

Converting across quantities

Turning becquerels into sieverts (or grays into becquerels) with a single factor is invalid — they measure fundamentally different things.

Confusing gray and sievert

Gray is absorbed energy; sievert weights it for biological harm. They're numerically equal only for some radiation types, not in general.

Dropping a dose prefix

Reading mSv as Sv overstates a dose 1,000-fold — turning a routine scan into an apparent emergency. Prefixes are critical here.

Mixing dose and dose rate

A total dose (Sv) and a dose rate (Sv/h) differ by a time factor. Treating one as the other misjudges exposure.

Why Radiation Conversion Matters

Radiation units sit at the heart of medical imaging, nuclear safety, and occupational dose limits — and the field still mixes the old units (rem, rad, curie) with the SI ones (sievert, gray, becquerel). The deepest pitfall is that 'radiation' isn't one quantity: absorbed dose, equivalent dose, and activity are distinct, and converting across them with a single factor is simply wrong.

Because dose figures drive safety decisions and patient records, and because a dropped prefix can turn a harmless exposure into an apparent crisis, precise conversion within the correct quantity is essential. A converter that keeps sievert/rem, gray/rad, and becquerel/curie in their proper lanes lets clinicians, health physicists, and safety officers work reliably across both systems.

Built for radiologists, health physicists, nuclear workers, and safety officers converting between sievert, gray, becquerel, and their old-unit equivalents.

Linear unit factors follow the BIPM SI brochure, the NIST Guide to the SI, and ISO 80000. Currency rates load live from open.er-api.com; crypto prices from CoinGecko. See our methodology and editorial policy. Educational only — not certified for regulated trading, settlement, medical, or aerospace use.

Radiation Dose Converter FAQs

Multiply sieverts by 100 to get rem, since 1 Sv = 100 rem. So 1 mSv equals 100 mrem, and a 0.1 mSv chest X-ray is 10 mrem. The same factor of 100 converts grays to rads for absorbed dose (1 Gy = 100 rad).

A gray (Gy) measures absorbed dose — the energy deposited per kilogram of tissue. A sievert (Sv) measures equivalent dose — that energy weighted by how biologically harmful the radiation type is. For X-rays and gamma rays they're numerically equal, but for alpha particles the sievert is much larger, reflecting greater harm.

Not with a single factor. Becquerels measure activity (decays per second of a source), while sieverts measure the dose received by something exposed to it. Converting requires knowing the radiation type, geometry, distance, time, and absorbing material — it's a physics calculation, not a unit conversion.

One curie equals 3.7 × 10¹⁰ becquerels — 37 billion decays per second. The curie was based on the activity of one gram of radium. The becquerel (one decay per second) is so small that practical sources are quoted in kilo-, mega-, or gigabecquerels, or in microcuries and millicuries.

A typical CT scan delivers an effective dose of about 2–10 mSv (200–1,000 mrem), depending on the body region, compared with about 0.1 mSv for a chest X-ray. For context, natural background radiation is roughly 2–3 mSv per year, so a CT scan is on the order of a year's background exposure.

It uses exact definitions within each quantity (1 Sv = 100 rem, 1 Gy = 100 rad, 1 Ci = 3.7 × 10¹⁰ Bq) and routes conversions through the SI unit of each quantity at full precision, so the result is exact to your input precision — provided you convert within the same quantity.