How do you know which size to order online? You measure, you don’t guess

The parcel arrives, you open it, you try it on, and it fits. First time.

No repacking, no post office, no ordering the same thing again in another size.

All that stands between you and that is a tape measure and two minutes, once.

Why is this even a question? Because the number on the shoe and the letter on the shirt are not your measurements, they are the brand’s. The shoe site RunRepeat measured shoes in the same US size 9 and found internal lengths anywhere from 255 to 281 millimetres. A 26 millimetre spread, almost two full sizes, on the exact same number.

And clothes are looser still, because there isnt a number at all. There is a letter the shop picked.

So we switch to centimetres. A centimetre is a centimetre in every brand, on every site, in every language.

Shoes: measure your foot once, and use that number forever

1. In the evening, after youve been on your feet. Your foot spreads over the day, and that is the foot that goes into the shoe.
2. With a sock on, the same kind youll wear with this shoe.
3. A sheet of paper on the floor, heel against the wall. The wall is what holds the heel still, otherwise the measurement slides and you get a different number every time. Stand with your weight on both feet and mark lightly at your longest toe.
4. Both feet, not one. Most people have a difference, and the size is set by the bigger foot.
5. Measure from the wall to the mark. That is your number.

Now the part most people skip: open the size chart of that specific model, not the brand’s general one and not the site’s. Find the row that says foot length, and take the size that matches your number.

And you need room in front. The rule: the inside length should be at least half a centimetre longer than your foot, and for running give it a full centimetre. Between two sizes, take the bigger one. A shoe that is slightly big is solved with a sock. A shoe that is too small is solved with nothing.

And here is why this is not theoretical: a 28.4 centimetre foot is a size 46 in Adidas and a 45.5 in Nike. Same foot, two numbers. Order a 46 in Nike because that is what the Adidas in your closet says, and the shoe arrives too big.

Clothes: measure something that already fits you, do not pick a letter

S, M and L are not sizes. They are a letter the shop chose. On the Chinese sites sizes tend to run smaller than you are used to, and the same M from two shops is two completely different garments.

So do not guess what you are. Show the chart what already fits you.

Take a shirt or a pair of trousers you like the fit of. Lay them flat on the table, no stretching, and measure:

• Chest: armpit to armpit, doubled if the chart asks for a circumference
• Length: from the top of the shoulder down to the hem
• Shoulders: seam to seam
• Sleeve: from the shoulder seam to the cuff
• Trousers: waist circumference, and the inseam from the crotch to the hem

Five measurements, two minutes, and you compare them to the chart of that product itself.

Two things that save you a mistake. One shop’s chart does not apply to another, not even on the same site. And if you want a loose fit, add the centimetres deliberately, because you measured a garment that exists and not the one you are hoping for.

I dont guess sizes, akhi. I measure them. Two minutes once, and after that every order is a ten second check.