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Lost Socks Calculator

Created by Piotr Małek and Bogna Szyk
Reviewed by Steven Wooding and Jack Bowater
Last updated: Jun 05, 2023

How many times have you unloaded the laundry, only to realize that one of your socks is missing? We've all been there; this problem has been affecting millions ever since socks were invented by the ancient Greeks back in the 8th century BC. While we still don't have a perfect solution to this particular problem, we have something even better: the Sock Loss Index calculator. Use it to find out how many socks go missing in your household per month, and how much money you spend on replacing them.

A foolproof sock loss equation

As you might expect, you're not the only person who's fed up with socks disappearing mysteriously from the washing machine when you're not looking. The issue got so much attention that a special study on the Mystery of The Missing Sock was commissioned to investigate the scale of the problem.

Missing sock.

Psychologist Dr. Simon Moore of Innovationbubble, a behavioral strategy agency, and statistician Geoff Ellis at Evolution met together to analyze thousands of cases of lost socks and came up with a foolproof formula:

Sock loss index = [L(p * f) + C(t * s)] - (P * A)


  • L stands for laundry size, calculated as the number of people in the household, p, multiplied by the frequency of washes over a week, f;

  • C represents washing complexity, and is found by multiplying how many types of wash, t, your household does in a week, by the number of socks, s, washed in a week;

  • P is your positivity towards doing laundry, measured on a scale from 1 to 5;

  • and A stands for degree of attention - that is, the number of precautions taken before doing the laundry. Precautions might include checking pockets, unrolling sleeves, turning clothes the right way, and unrolling socks.

We went a step further to find out how much money you lose on replacing all these missing socks - feel free to check it out in the advanced mode of our Sock Loss Index calculator. We assumed that for each sock lost, you buy a new pair. (What happens to the single sock? We recommend making a sock bun).

🙋 Our dress size calculator can help you find your perfect fit!

Where do all the missing socks go?

Even though most people suspect that fairies, the machine god, or hungry alligators are on the hunt for their socks, scientists have found an answer to this question as well. (They love spoiling the fun of the guessing game, don't they?) Apparently, the culprit is hiding in plain sight: it's your washing machine.

It's true: your washing machine is perfectly capable of devouring socks from time to time. You can find them in most surprising places if you disassemble the device; they might end up between the inner and outer drum, in the drain pipe, or behind the agitator.

Nevertheless, the study discovered that the average Brit loses an astounding 1.3 socks every month, which translates to 15 socks a year. Now, imagine a family of four that has a five-year-old washing machine. Unless their machine is actually a giant cloth moth in disguise, it's not physically possible to fit 300 single socks in its insides.

That leads us to a surprising conclusion: the main criminal, it turns out, is... you. Or, to be more precise, you and all the other people living in your household.

🙋 Convert between different shoe sizes with our shoe size conversion tool!

How to decrease your Sock Loss Index?

Why are you responsible for all of those socks going missing? The main problem is usually absentmindedness. Researchers found that we don't often notice when we drop socks behind radiators or furniture. We're also guilty of being careless when securing our socks to a washing line - some of them fall off and get blown away towards the horizon, ready to start a new life.

Luckily, there's a remedy for this lack of attention. We have compiled a list of tips that will ensure your socks stay where they belong.

  1. Switch to socks that aren't colorful. According to the study, colored socks make up for 55% of all socks that go missing! White, stripy or spotty socks are well-mannered and don't wander off that easily.

  2. Reduce the number of socks you own. This might seem counterintuitive, but the more loads of laundry you do, the higher the probability of misplacing a sock is. If you pare down on the number of types of laundry and their frequency, you will be able to keep more socks in your drawer!

  3. Change your attitude. The more you enjoy laundry, the more attention you pay to it. In consequence, you'll be more aware of any socks that avoid their duties and go AWOL.

  4. Go on a sock hunt. It's natural to search for missing socks in only the most obvious places. Instead of giving up when you don't find them in the laundry basket, go around your apartment and search again. They don't have to be lost forever!

Sort your socks like a pro(fessor)

Let's say you prevented your washing machine from eating all of your socks, and have now gathered a massive pile of socks in front of you. Is there a most efficient way to sort them? Apparently, the answer is yes.

In their book Algorithms to Live By, cognitive scientist Professor Brian Christian and science writer Tom Griffith recommend an algorithm known as a radix sort (widely applied in computer science) to sort your socks.

How does radix sort work? Instead of picking one sock from the pile and searching for its twin, you should separate all socks into subgroups - for example, by color. You can even subdivide the socks again according to a different criterion (let's say length). Then, it's much easier to match socks within these smaller piles.

If you don't have a lot of socks, the authors suggest you could try using the pigeonhole principle instead. This principle says that if you pick half of all the socks plus one, then you're certain to find at least one pair. For example, if a load of laundry contains ten socks, pick six of them at random. This smaller pile will contain at least one pair of socks that you can match.

Are all these algorithms giving you a headache? Well, there is always a more straightforward solution: buy only one type of sock!. If all your socks are identical, there's no need to sort them!

Check sock size calculator to learn how to calculate sock size!

Piotr Małek and Bogna Szyk
Related calculators
People in household
Precautions taken
Types of washes
Number of washes
Attitude towards doing laundry
I like it
Total socks washed
Chance of losing a sock
Socks lost
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