Leisurely lunches are a great way to spend the afternoon, but often occur at upscale restaurants where nicer clothing is required. For lunches like these, business casual attire is the right choice. Business casual lunch clothes can allow you to dress comfortably but still follow appropriate dress-code guidelines.
Lunches are more formal than breakfasts, but still far less formal than dinners. For a lunch, lighter colored pants and shirts, brown shoes, a brown belt and matching socks are appropriate. Chino pants or other lighter-weight materials work perfectly. Darker colored and heavier fabric pants can also be worn, but are most likely not required unless the occasion is more formal.
Lunches can often be outdoors - remember appropriate jackets or sunglasses
As with any meal, remember to avoid spilling food on your clean clothes
Most restaurants do not have a dress-code for lunch