Imperfect Stopwatch

[PoetLearnsPython]

Hey, I'm new here so if I break any rules, feel free to scold me.

Anyway, I was learning how to program a simple timer from a YouTube video. I got everything to work, and tweaked a few things myself. But when I compared it with an independent timer (phone and computer timer), I noticed that it runs a bit slower. By the two minute mark it's about 15 seconds behind the independent timer. Is there a way to improve this or would I have to completely start from scratch to get a more accurate one?

Oh, and I'm running 3.7.

Here's the code:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

import time from os import system   seconds = int(0) minutes = int(0) hours = int(0)   run = input("Enter R to run the program\n")   while run.lower()=="r":     seconds = (seconds + 1)     if seconds > 59:         seconds = 0         minutes += 1           if minutes > 59:         minutes = 0         hours += 1     system('cls')     print(hours,":", minutes,":",seconds)     time.sleep(1)

[ichabod801]

Well, you're waiting a second, then doing some stuff, and then waiting a second, and doing stuff, ... Doing stuff takes time. Printed output especially takes time. So it's going to be slower than an accurate stopwatch.