Updated: May 26, 2021
Stride length is a bit tricky because everyone has different leg lengths, run style, weight, speed and body composition. So to create a ‘rule’ that generally applies for stride length to all runners, people talk about cadence. Cadence is how many steps you take per minute (both feet).
Cadence is great because no matter your speed, it should be about the same. Remember that these are general guidelines and the best thing to do is listen to your body. I personally find that my cadence is a bit lower (longer strides) when I’m running slow versus when I’m doing a speed workout or racing. But I’m also not a professional runner, so I may not be the best example. Keep in mind that we are all approaching perfect form and that as your body, muscles and speed changes your stride will change as well. Do what works for you now and continue to play with these mechanics as you improve.
The general number for cadence right now is 180 steps per minute. Like anything, there is debate around this, but for beginners, it's a good target to work towards. If that's hard to visualize or apply, I like to think of it as three steps in a second, which may seem awfully fast. Remember this is a target to work towards. If you try to force or over analyze this target (or any other aspect of run form), you will probably throw off your natural stride and feel awkward. So use these as guides to work towards while still feeling natural. It takes time to gently change your run form, which is great because you want to adapt as your weight, muscles and speed adjust.
The nice thing about cadence is that it shouldn't be based on speed. As you go faster your stride length will increase, but the general principle of three steps per second should stay the same. And as you slow down, your stride length will shorten and your three steps per second will stay the same.