A pocket square with jeans is not a costume. It is a cloth in a pocket that was built to hold one.
Most pages will tell you to wait for a jacket. A few will tell you never to put one in a shirt. They are writing about weddings. This is about leaving the house.
He wore one anyway
My grandfather never left the house without a jacket. He always had a cloth in the breast pocket. Even in jeans. Even for a dinner that was not an event.
He was a Liverpool lad. The street the shop was on is still being pinned down. The year too. The habit does not need either.
He sold suits. The cloth was part of how he finished a man. Not extra. Required.
Forget the wedding rules
A pocket square is not married to a suit. It is married to a breast pocket.
If you have a jacket on, the cloth goes in the jacket. That is the clean version. Dark jeans. Plain shoes. A jacket you would actually wear to the shop. The cloth shows a strip or a small puff. Nothing that looks like a flower.
If you do not have a jacket on, you need a real chest pocket. Jeans side pockets are not it. A coin pocket is not it. A flap that will not sit is not it.
Guides that say skip it without a jacket are protecting a rule. They are not looking at a man who dressed this way every day.
What cloth
Cotton or linen. A bit of texture. Bone, white, navy. Pick one and stop.
Silk is for a room with a dress code. It slides. It shines. It fights denim. Save it.
Size: a proper square. About thirty to forty centimetres. Not a scrap from a cutter’s bin. Not a napkin.
Do not match it to a tie. There is no tie. Do not match it to your socks. The cloth is allowed to disagree with the jeans. That is the point.
Navy jeans, bone cloth. Light jeans, navy cloth. If both are dark, show less of the cloth. Let it sit.
How to fold it
Two folds. That is enough.
The flat fold. Fold to a strip. Tuck until a band of cloth shows at the top of the pocket. Straight. Quiet. Good for jeans. Good for a jacket on a Tuesday.
The puff. Pinch the middle. Push it in. Let it sit. Do not sculpt it. If it looks considered for more than three seconds, pull it out and do the flat fold.
Skip the points. Skip the crown. Skip anything you have to watch a video twice to copy. The fold is not the story. The fact of the cloth is.
Show a little. A centimetre or two. If it looks like a flag, you have too much out.
Jeans
Dark. Clean. A straight leg. Distressed denim fights the cloth. So does a very light wash. You are not going to a wedding. You are also not pretending the jeans are a suit.
Belt if the jeans need one. Plain. No theatre.
Shoes that have seen a pavement. Not trainers with a dress code in the name. Not patent.
The rest of the outfit should be able to survive the cloth being taken out. If the whole look collapses without it, the look was the cloth. Put a jacket on and start again.
No jacket
This is the part the internet hates.
A shirt with a real chest pocket can take a flat fold. Cotton cloth. Very little showing. If the pocket gapes, or the shirt is too light, leave it. A sagging pocket with a handkerchief stuffed in it is worse than none.
A T-shirt with a pocket is the grandson version of the same habit. An empty patch pocket looks leftover. A cloth gives it a job. Cotton again. Flat fold. Navy on navy is fine if you show almost nothing. Contrast if you want it read.
If the pocket is too small, do not force it. The cloth should live there. It should not bulge. It should not fall out when you sit, or when you get in a car. If it does, the pocket is wrong, not the idea.
What not to do
Do not wear a square to prove you know a rule.
Do not buy a matching set in a gift box and use both pieces in the same pocket.
Do not iron a razor crease into linen and then pair it with jeans. The cloth can look used. His did.
Do not put it in the back pocket of the jeans. That is a different object.
Do not wait for a photograph of him in a suit. We do not have that pinned yet. The instruction does not need the picture. Jacket on. Cloth in. Leave the house.
The only test
Put it in. Walk to the door. If it feels like a bit, take it out. If it feels like you forgot it was there, keep it.
He never left without it. That is the whole lesson.