If you remove the foam and steamed milk from a cappuccino, you’re basically left with a shot of espresso. So we are comparing espresso and regular dripped coffee.
A single shot of espresso contains roughly 40 mg of caffeine per ounce, whereas a brewed cup of coffee using an auto drip machine only has around 10 mg in each ounce. Obviously, this will vary depending on the dosage and the amount of water used. But it’s a good starting point.
So. 2oz shot of espresso: 80mg caffeine. 8oz cup of drip coffee: 80mg caffeine. About the same amount of caffeine.
But we haven’t factored in ingestion time. Generally, you enjoy a shot of espresso in under a few minutes, while you will take longer to drink a cup of brewed coffee.