I'm mounting different toilet tank on an old bowl. What is the mounting bolt spacing of a typical toilet tank? By this I mean the 2 bolts that attach the tank to the bowl.


3 Answers 3


There is no spacing standard, friend.

Tighten all them by hand first then go around and tighten them until you think its good. You don't wanna tighten too much because it'll break the toilet. After you tighten them check 4 leaks. If it leaks then tighten them.

The tank will always have a little wobble, unless its installed close to the wall, so you'll want to ensure if its free standing, meaning nothing is bracing it, tighten it to a degree that there is a bit of stiffness in relation to movement and you should be fine.


I have toilet with a 2” flush valve and the mounting holes are 5 3/4” apart measured from center to center

I also have a toilet with a 3” flush valve the distance between the two mounting holes measured from center to center is 6 1/4 “


You're talking about 'tank-to-bowl' bolts spacing. I think the span, 6 inches, centre to centre, has been standardized within the industry for a long time now, maybe for the last 40 years? If you're not sure, measure them first.

  • 2
    Hi Chris. I have done a huge amount of plumbing. There are many models that will absolutely not match up. There is no "STANDARD" in the industry. Some models can be as little as 1/4" different all the way up to a full inch difference. If they were all mandated to be the same, manufacturers would lose a ton of money. Commented Jan 31, 2019 at 20:40
  • 3
    The floor flange has standard 6-inch spacing AFAIK. I can't see the tank-to-bowl being standardized.
    – mike65535
    Commented Jan 31, 2019 at 20:50
  • Hah! Good point! They don't like mixing and matching. Commented Jan 31, 2019 at 20:58
  • I even have a toilet tank with 3 mounting bolts.
    – Glen Yates
    Commented Feb 16, 2023 at 20:13

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