Even a suit can be informal. There’s some details that make a difference. Not all of them are equally important though.
Every little detail counts. Almost everything about the cut of the suit jacket can make it a little more or a little less formal and official. And if you’ve read about this before, you know what I mean: peak lapels are more formal than notched ones, patch pockets are less formal than flapped ones, but none are as formal as besom ones. One button closure is the most official. So are two vents as opposed to one.
While this is all more or less true, I tend to disregard most of these things. Because, sure, one button closure makes the suit a little more similar to a tuxedo, and therefore more official – in theory. In practice, one button is a signature style of Huntsman sport jacket – and that doesn’t look too formal to me.
I’ve been arguing about that with Mikołaj from Blue Loafers several times. He scoffs at my three-piece suits with patch pockets, because that’s too informal a detail to pair with a waistcoat. He expressed disdain at the notion of wearing a jacket with besom pockets with jeans. And I couldn’t disagree more, because I think those things don’t matter anymore.
I’m not saying, mind you, that there’s no formality difference between tailored garments. Quite the opposite in fact. But there are some things that have the power to decide this aspect easily and ultimately; everything else comes down to aesthetic choice.
The most important thing is the fabric. Smooth worsted wool in dark colour is formal. Texture, pattern, bright colours – that brings this formality down. A navy or charcoal worsted wool suit is formal nowadays; you can add peak lapels to accentuate it, but it is something few will notice. Most will concentrate on the colour and the delicate sheen of the material. If you go with flannel, tweed, rough hopsack weave wool – you’ll get a less formal garment. If you make it brighter in colour, and add some plaid pattern – you take another few steps down the formality ladder.
Another thing is construction. The typical British tailoring with strong shoulders and padded chest has those clean lines and looks more like a military uniform. This also has a formal vibe, and looks more serious than a soft-shouldered jacket. But I’m putting it on a second position because there are exceptions: like the Huntsman jacket I linked above.
Those two things are, in my opinion, decisive. Other stuff is for purists to stress over and enthusiasts to play with.
And there can be a lot of playing – I remember a suit Alex from Monokel Berlin wore to Pitti 92. Made of navy pinstripe worsted wool – the fabric and subdued business pattern would place it rather high on the formality ladder, as a conservative, office-appropriate wear. But it had very soft construction and details like patch pockets with buttoned flaps. This was a deliberate inversion of what you’d expect to be made from this fabric – it worked quite nicely, and I would see it as rather informal option.
But if you’re looking just for things to wear and not neccessarily make a statement on Pitti, I really wouldn’t worry that much. If you need a nice suit for suit-wearing occasions, go with dark worsted wool, and perhaps more constructed. If you want a suit to break into separates, and occasionally wear as a whole, but without looking to stuffy – go with something with nice texture, lighter colours, and perhaps some pattern – and maybe with soft shoulders.
And whichever type of pockets or lapels you prefer with that.