It's hard to quantify how big the leak is, but the IP holds steady. I'm just not sure whether the leak is lowering the displayed pressure, and if it is, by how much. I was surprised that it leaked at all, so perhaps I got a dud? It eligible for a free return so I'll just do that and see if the replacement leaks and go from there. Thanks for confirming, and for the guide! That 4" winters gauge is a big step up from the smaller one I was borrowing from a friend.That’s odd, mine doesn’t leak; it shouldn’t leak at all, I think this would definitely throw the gauge off, but if it’s very small I don’t think it would matter.