# Science Questions

Sat, 30th Oct 2010

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### Question

What is the total weight of red corpuscles formed in a life time?

The average adult makes 200 billion red blood cells every single day.  It’s about 2 ½ million every second, which is absolutely incredible. You've got about 20 to 30 trillion in your circulation and you have to replace that – about 1% of them - every single day.

You kill 1% of them and you make another 1% of them.

So, it should be fairly simple: you just take the number that get made every single day, you times it by how many days in a year - 365, you times that by 75 years in a lifetime, and then you times it by the weight of a red blood cell, and you get the answer.

How much does a red blood cell weigh? Well I had to look for that and it turns out, the weight of a red blood cell can change across your lifetime.  I found a paper by Mischlinzski and Koshak who are from Gdansk Medical School and they tell me that the weight of a red blood cell is, on average, about 45 picograms - 45 x 10-12 grams - per cell.

So, if you times all those numbers together, you get 246,375 grams of red blood cells made in a lifetime, which is 246 kilograms or a quarter of a tonne, an absolutely staggering number, or weight, of red blood cells.

Reference: Andrzej Mysliwskia and Anna Korczak, Mechanisms of Ageing and Development, Volume 34, Issue 2, April 1986, Pages 111-115