My toilet tank keeps running

Karen Treche :) Hello .... I found this article from Family Handyman with a video there to tell you how to check for the problem and what to do about it:

https://www.familyhandyman.com/plumbing/toilet-repair/how-to-stop-a-running-toilet/view-all/

I sure do hope this will help you. Thanks for using HOMETALK for answers :)

make sure the float is at the right height to cut off water when filled

It may be the seal on the bottom of the tank.

adjust the float

In my case, when it wasn't the flapper it was the fill valve.

https://www.fluidmaster.com/products/toilet/fill-valves/400a-universal-fill-valve/

Check to make sure the water cut off valve is set to cut off the water flow a little before the water height starts pouring back into the tube. Also, it the water is still flowing into the bowl, (you'll see water movement in the bowl after it fills) you may need to adjust the flapper a little up , down , or make sure it is sealing as it should.

Thanks so much for taking time to answer my question. I was thinking that was my last option before replacing the whole toilet! Thanks again!

Thanks for taking the time to answer my question. May you know the answer to this. Is there supposed to be a seal the flapper sits on or just rest on the hole in the bowl? Thanks again

I USUALLY FILL A FEW EMPTY BOTTLES AND PUT THEM INSIDE TO TAKE SOME OF THE WATER VOLUME AWAY.

It's supposed to sit on a seat which is sealed to the hole. See attached picture.

Try to make sure that the chain is just right so that when you pull the handle it will lift the flapper right away. My toilet leaks on and off after replacing the flapper. I couldn't figure out until I adjusted my chain.