What to WearParis has an informal but genuinely real dress culture, and it rewards a slightly more put-together look than a lot of other major destinations. This isn’t about rule-following so much as understanding that personal presentation carries more social weight in French culture than it does in plenty of Anglo-American contexts — and it shows up in small, practical ways, like how you’re received in restaurants and shops.
The baseline that actually works: smart casual rather than obvious tourist gear. That doesn’t mean any particular style — Parisians aren’t especially formal, they just tend to dress with a certain effortlessness that’s more about fit and proportion than logos or price. Comfortable walking shoes that also look reasonably presentable, rather than pure performance footwear, fit the Paris street naturally.
Museums and most churches have no strict dress code beyond the general modesty you’d expect in any religious space. Notre-Dame, both a major tourist site and a working cathedral, calls for covered shoulders, and a number of Paris churches enforce this more strictly than the major museums do.
Seasonally, Paris has real autumn and winter — pack layers and a proper coat from October through March, and lighter, comfortable clothing for mild spring and summer, with a light jacket for evenings regardless of season given how much the temperature can drop after dark.