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Radiation Dose Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Anna Szczepanek, PhD and Steven Wooding
Based on research by
US Environmental Protection Agency Radiation Protection;; Accessed 10.2022See 1 more source
Al-Shakhrah IA. An indirect high iodine (131I) effective dose used for thyroid ablation in patients with thyroid cancer. Is the method of measurement important?; Journal of Applied Clinical Medical Physics; July 2020
Last updated: Jan 18, 2024

The radiation dose calculator allows you to find out the amount of ionizing radiation that accompanies you in your everyday life. ☢️

Our tool will guide you through the meanders of mrem radiation from medical, natural, and everyday life sources. We'll also talk about radioactive decay, different doses of radiation, and their possible harm to human health and life.

Read on to find out:

  • What is radiation dose measured in?
  • How much radiation does the average human receive each year?

What is radiation and what does it do?

Ionizing radiation consists of alpha, beta, and gamma rays. Ionizing radiation bears the power to tear apart electrons from atoms and particles. The radioactive decay of different atomic nuclei produces such radiation.

Radioactive atoms are present in the ground, the food we eat, and the air we breathe – they also bombard us constantly from cosmic space. Humans learned to produce artificial radioactive substances for medical and war purposes.

In medicine, physicians use radiation to diagnose and treat different diseases and states.

  • X-rays and computer tomography (CT) allow us to look inside the human body – they're used every day in hospitals worldwide.

  • Radioactive elements are also needed in cancer treatment – the radiation is served precisely to the center of the neoplasm, killing its cells. Radiotherapy can be applied externally via the beam machine or internally by placing a capsule into the location of a tumor. If we want to compute the total effect of radiotherapy treatment, we use the biological equivalent dose (see BED calculator).

  • Mammograms save thousands of women every year, detecting early forms of breast cancer.

  • Radioisotope of iodine eliminates possible leftovers of thyroid cancer cells – it is also efficient in treating Graves' disease.

Large amounts of radiation can be lethal to humans – high-energy rays destroy DNA, leading to multiple organ failure and subsequent death due to radiation poisoning.

💡 The lethal radiation dose is 400,000-450,000 mrem – such an amount would kill 50% of the population within 30 days.

Try to compare this number with your annual radiation dose computed with our CT radiation dose calculator!

How to calculate radiation dose?

To calculate the radiation dose, you will have to add all the possible sources of radiation you might have had contact with.

  1. Start with the natural sources. Internal, cosmic, and terrestrial radiation and sea level account for ~ 287 mrem/year.

  2. Continue with everyday life. Use the table below.


Radiation in mrem/year

Cigarettes smoked

0.49 per pack

Travel by plane

1 per 1000 miles (1600 km)

Porcelain veneers/crowns


Radiation worker

Individual dose

Stone, brick, concrete building


And many others...

  1. Move on to medical sources.


Radiation in mrem/year



CT pelvis/ abdomen scan


CT chest scan


CT head scan


And many others...

  1. Everything added and ready? Enjoy your results. 🎉

💡 Learn details about specific radiation sources using our flight radiation calculator and medical radiation calculator.

Other radiation sources

What are other rare radiation sources not included in our radiation dose risk calculator?

  • ❤️ Plutonium-powered pacemaker – a pacemaker is a device that artificially maintains the rhythm of the heart. A plutonium-powered mechanism could easily outlive its owner while delivering reasonably low doses of radiation (100 mrem/year). Such devices were ditched because of dangers connected to handling plutonium as well as the discovery of lithium batteries.

  • 📺 Old TVs with Cathode-Ray Tube used to emit some amounts of ionizing radiation; the TVs we use nowadays might be the source of non-ionizing radiation only.

  • Luminous wristwatches (LCD) – especially popular during the '90s, with screens that glow in the dark.

  • 🚀 Weapons test fallout estimated 1 mrem/year in some regions. 1963 was the peak year of radioactive fallout; its level has been decreasing since then.

How much radiation does the average human receive each year?

The average annual level of radiation for the US citizen is equal to 361 mrem/year.

🚬 If you smoke tobacco, you should add an additional 280 mrem/year.

What is radiation dose measured in?

We can measure radiation in a variety of different units. Let's explain some of them:

  • mrem (milirem); and
  • mSv (millisievert) – both of these units describe the health risk and biological effects of radiation.

100 mrem = 1 mSiv

  • Gy (grey); and
  • rad – both measure the physical quantity of absorbed radiation.

1 rad = 0.01 Gy

What's the annual dose limit for radiation workers in msv?

Adults working with radioactive materials should limit their exposure to 50 mSv per year.

50 mSv is equal to 5000 mrem – the amount of radiation equivalent to that of 5 abdomen/pelvis CT scans.

Łucja Zaborowska, MD, PhD candidate
Natural sources - background radiation
Your body's internal radiation
Cosmic radiation (sea level)
Terrain elevation
Sea level (none)
Terrestrial radiation
Everyday life sources - during the past year:
I smoked
cigarettes per day
Lived next to a nuclear plant?
Lived next to a coal-powered plant?
Lived in a stone/concrete/brick house?
Had a smoke detector?
Used gas lantern mantles?
Wore porcelain crowns/ veneers/ false teeth
Worked as a radiation worker
Long-distance travel
by plane
Passed though
airport screening devices
Had your luggage X-ray scanned?
Medical sources
Number of X-rays
CT scans: pelvis/abdomen
CT scans: chest
CT scans: head
Thyroid ablation with radioactive iodine
Annual radiation dose
Radiation dose
Radiation from:
Natural sources: 100%
Everyday life sources: 0%
Long-distance travel: 0%
Medical sources: 0%
💡 Your radiation dose is lower than that of an average US citizen.
Check out 3 similar radiology calculators ☢️
BEDMedical RadiationTI-RADS
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