A typical 8 oz (240 ml) cup of brewed coffee has about 95–120 mg of caffeine , but the range can be wider depending on how it’s made.

Quick Scoop (main numbers)

  • Standard brewed coffee, 8 oz: about 95–120 mg of caffeine.
  • Espresso, 1 oz shot: about 60–70 mg (but it’s more concentrated per sip).
  • Instant coffee, 8 oz: around 60–70 mg on average.
  • Decaf coffee, 8 oz: usually 2–10 mg , not zero.

Why the numbers vary

The caffeine in “a cup of coffee” isn’t fixed; it shifts with:

  • Cup size : Many mugs are 10–12 oz, so they can easily reach 113–247 mg of caffeine per cup.
  • Brew method : Drip, French press, cold brew, espresso, and instant all extract caffeine differently.
  • Beans and roast : Robusta beans have more caffeine than Arabica; grind size and roast level also change extraction.

Think of “about 100 mg per 8 oz” as a handy rule of thumb for everyday brewed coffee.

TL;DR:
Most people drinking a normal mug of brewed coffee are getting somewhere in the 95–165 mg caffeine range, depending mainly on cup size and brew style.

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