How do I clean a stubborn toilet bowl ring??

We've had a lot of success with CLR or other 'rust killer' type cleaners. Most stubborn toilet rings are mineral buildup based. You could also try draining the bowl and filling it with vinegar. Might take longer to soak.

You can also add a can of Coke to the inside of the toilet and let soak for an hour, then a rain with a brush and flush!

I tried all of the previous answers and they didn’t work on my toilet ring. I used a pumice stone and ring is gone!

When using a pumice stone be sure to keep stone and toilet bowl wet. A dry stone will scratch the toilet bowl -- I learned the hard way!

My solution was the pumice stick. This is excellent way to remove stains and rings in the toilet. When commercial toilet cleaners fail -this is my go to. Great for thick crusted calcium mineral build up that the toilet waterbowl collcts.

They are found at my local Walmart for less than two dollars -good for multiple uses. Be sure to follow the use instructions, soaking the pumice stone in water for a few minutes. While the stone is soaking, grab your toilet brush and splash water up around the ring. Note: It’s very important to keep both the stone and the surface wet while cleaning to avoid scratching your porcelain.