Is it normal that my heart rate is always over 100?

as long as its not OVER 9000!

Wow, have u seen a doctor?

If you drink or eat things with caffeine
that will do it also smoking, doing weed

Double check again and make sure you're relaxed when you do it.

Listen and count your heartbeat for 10 seconds.
Afterwards multiply that by 6.

That's weird, active people tend to have slower, more strong heartbeats. You should see a doctor if you start to feel dizzy, lethargic, or confused.

Are you anxious?

Can you see your heart pulsing between ribs or shaking your chest?

Mine too, it has always been high. I am prone to anxiety and panic but no matter what my weight mine is always around 100-110.

if your heart rate is between 100 and 120 at the age of 18 their could be several reasons. some of those might be stress or extra sugar in your diet, their could also be too much stress in your life like maybe collage or high school maybe even excitement of moving out or being an independent adult. One way you could cut back on stress is just by cutting back on extra curricular activities, or maybe just taking 30 minuets or 1 hour a night just to relax. If none of this works then i would defiantly recommend going to a doctor but if you were to not try this before going then they would just recommend the same things for hundreds of dollars.