Tachycardia in an adult is generally classified as a heart rhythm with a rate that is:

• A. Less than 60 beats per minute
• B. 60 to 100 beats per minute
• C. Greater than 100 beats per minute
• D. More than 120 beats per minute

Answer: (C)

In adults, the resting heart rate normally sits around 60–100 beats per minute. Tachycardia means the heart is beating faster than the normal resting rate, so the general cutoff is more than 100 beats per minute. This is why the category of rates above 100 bpm best fits tachycardia. Rates below 60 bpm describe bradycardia, and rates within 60–100 bpm are considered normal resting rhythm. Rates above 120 bpm can occur, but the standard definition of tachycardia is simply a rate over 100 bpm.