The astonishing misplaced confidence of some men has been on show again, with one very clever chap attempting to mansplain menstruation to women – using maths

How many tampons do you need? This man will explain

This week, mansplaining on the internet reached giddy new heights as one man tried to calculate just how many tampons are necessitated by “the average period”.

A Twitter user shared a screengrab of a comment, posted on PinkNews’s Facebook page by a plucky gentleman outlining how women might be able to manage their periods affordably with only his trusty man-brain and the power of maths. To his credit, the maths was correct – it was just everything else that was wildly wrong.

“So the average period is 10 to 35ml of blood, each tampon holds about 5ml, so seven tampons per cycle,” he began. “Lets be generous and say 10 for those ladies with an extra-juicy uterine lining. Nine periods a year equals 90 tampons max,” he concluded, before going on to refer to a 64-pack of tampons listed for £7.90 plus shipping on Amazon (“Buy two packs, save on shipping”).

“I bet he wore a lab coat while he wrote that,” someone commented on Twitter.

Personally, I only wish it could have gone on for longer. If you’re reading, sir – please continue! How absorbent are these tampons you’re talking about, and what are your thoughts on applicators? What if my period flow changes midcycle? Please, help me with maths!

It’s astonishing, isn’t it, the confidence of a man to insert himself into a conversation about women’s bodies armed with nothing but some incorrect figures – but it happens all the time. Just last month, one overconfident fellow drew ridicule for arguing online, incorrectly and at considerable length, that a Guardian article headlined “Me and my vulva” was actually about vaginas – forcing Dictionary.com to wade in with the correct definition.

It is reminiscent of the story of astronaut Sally Ride’s first space flight in 1983, when Nasa engineers approached her to ask how many tampons should go in her kit for the one-week mission. “Is 100 the right number?” they asked. “No. That would not be the right number,” she replied. Of course, they questioned her again; she reassured them they could cut that number in half without a problem.

Because the thing is, men, women’s bodies needn’t be a mystery. All you need to do is listen.