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There's nothing quite as simple, relaxed and stylish as pairing a suit jacket with denim. The trick to ensuring a perfect match depends on ensuring that the jeans you pick come with certain "dressy" features:
Close fit: They don’t have to be skinny jeans, especially down below the knees, but there shouldn’t be any sag up around the thighs and crotch. You want a smooth outline of your body, not a drape of loose cloth that you can wave back and forth.
Dark color: Deep indigo is most common, but grays and black are also typical choices for nice jeans. More fashion-forward men may also experiment with white or very light gray jeans, or even brighter colors, but beginners should stick to jeans that are darker than the jacket.
Proper length: You’re going to be wearing nice-looking shoes with most of these outfits, and the cuff of the jeans should rest very lightly on the tops of the shoes when you stand straight.
The goal is to avoid pairing your jacket with jeans that look too worn, which means features like:
Severe fading or “acid wash” patches
Rips or tears of any kind
Fraying at the cuffs and pockets
Cargo pockets or gear loops
Remember that these style details aren’t mandatory, but you need to at least know the fashion rules before attempting to break them.

[Realmenrealstyle.com]