Pictures of this coronavirus have been published, and several details about its morphology, including a size around 120 nm.

My questions are:

  1. What is the weight of a single COVID-19 virus? Can we assume a density similar to water leading to a weight of 4/3*PI*120nm^3 / 1000 = 4.2 10-21 g if I'm not mistaken?

  2. Approximately how many viruses of this type are present in the body of someone infected (including asymptomatic carrier), and thus what is the average weight per person?

    This page states It has been estimated that there are over 380 trillion viruses inhabiting us, a community collectively known as the human virome

    However, it focuses on harmless viruses and healthy people. I haven't found numbers related to someone infected by a virus.

  3. How does this compares to poisons1? This article about the deadliest one, botulinum toxin, states: Extrapolating from its effect on mice, an intravenous dose of just 10⁻⁷g would be fatal to a 70kg person.

1 I understand it can't easily compare with poisons as a poison doesn't duplicates itself inside a body and the immune system, hopefully, plays a role here.

  • 1
    What medical use do you consider this information to have? What have you found online with your question? Welcome to MedicalSciences.SE Please take the tour and read the help center. For reasons mentioned in this post and in How to Ask, we require prior research information when asking questions. Please help us to help you and edit your question to provide more information on what you have read on this subject. What made you ask this question? This helps to provide an answer which will be more helpful. If you found nothing, what did you Google? Commented Mar 16, 2020 at 12:18
  • I'm voting to close this question as off-topic because it has no medical, scientific, or academic value.
    – Carey Gregory
    Commented Mar 16, 2020 at 14:57
  • @ChrisRogers I have edited my question. Let me know if you still think it still deserves being closed. Thanks.
    – jlliagre
    Commented Mar 16, 2020 at 15:38
  • As @CareyGregory points out, and I agree (see the first point in my previous comment), I still do not see any medical, scientific or academic value within your question so therefore it is questionable that it is likely to have an answer. Can you demonstrate specifically that your question has a medical value with similar scientific studies on weight of a single virus and how much viral load is required for sufficient infection to create symptoms? Commented Mar 16, 2020 at 15:46
  • @ChrisRogers I understand that the weight of this particular virus can be considered a futile piece of information but there is a study about the density of influenza viruses (jbc.org/content/159/1/29.full.pdf) from which we might deduce their individual weights, so that's not completely pointless. While I have removed that particular question from my list, I'm still interested in knowing the cumulative weight of all coronavirus spreading now, i.e. when the sum of infinitesimal quantities started to matter. Are we talking about, say, kilograms of viruses?
    – jlliagre
    Commented Mar 16, 2020 at 17:21

1 Answer 1


A single CoV-2-SARS virus weight is around one femtogram (10-15g).

An infected person contains between one billion and one hundred billion viruses, i.e. between one and one hundred micrograms.

Estimating the number of contaminated people at a given time to 50 million (including undetected cases), we reach a worldwide number of five hundred millions of billions viruses, with a cumulative weight being somewhere between 100 g and 1 kg.

Source: The total number and mass of SARS-CoV-2 virions in an infected person by Ron Sender, Yinon M. Bar-On, Avi Flamholz, Shmuel Gleizer, Biana Bernsthein, Rob Phillips, Ron Milo

Update: 2021-02-15: A more recent computation didn't focus on the weight but on the volume:

  • I'm curious what led you to ask this question. Now that you found this answer, do you foresee any scientific value to it?
    – Carey Gregory
    Commented Nov 27, 2020 at 20:05
  • 2
    Curiosity led me to ask this question, which by the way is the only one I ever asked on any SE sites, contrasting with 4000+ replies of my own. About its value, here is a quote from its source: The global impact of SARS-Cov-2 is clearly evident from its influence on public health and the global economy. Contrasting these global effects with the very moderate cumulative mass of these viruses highlights the limits of our day-to-day intuition in understanding and combating this pandemic and the need to rely on sound quantitative information rather than gut feelings.
    – jlliagre
    Commented Nov 27, 2020 at 20:18

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