You can relax: for regular aluminum foil, it doesn’t really matter which side goes up.

Quick Scoop

The short answer

  • Standard foil: Either side up is fine; shiny and dull sides cook the same.
  • Exception: Special “non‑stick” foils and some brands tell you which side should touch the food.

Why there are two sides

  • Foil gets its shiny and dull sides because two sheets are rolled together at the factory; the side against the rollers becomes shiny, the side touching the other sheet looks dull.
  • They are the same material and have essentially the same heat reflection and conduction, so food cooks the same on both.

When side does matter

  • Non‑stick foil (like Reynolds Non‑Stick or Bacofoil Non‑Stick): the dull side is coated so that’s the side that should face the food.
  • Tip: If the box says “non‑stick,” check the print—often, if you can read the logo, the non‑stick side is facing you and should go up toward the food.

Common “kitchen wisdom” vs reality

You’ll see lots of forum and Reddit comments saying things like:

Shiny side up to reflect heat, dull side up for crispiness, shiny for covering, dull for baking, etc.

But tests and official guidance (including from Reynolds and food authorities) say those differences are negligible for normal home cooking.

Practical rule of thumb

  1. Look at the box:
    • If it says “non‑stick,” put the dull/non‑shiny side toward the food.
  1. If it’s plain foil (no non‑stick label):
    • Use whichever side is convenient or looks nicer—your food will turn out the same.

Information gathered from public forums or data available on the internet and portrayed here.