Larger than expected, but a perfect fit for my 11’ cantilever patio umbrella with 39 or 40-inch crossbar.  Reviewers are correct when they say the hole is small and makes filling with sand (at least washed sand) difficult (it would have been impossible without a funnel, but difficult even with one).  Filled each halfway with washed sand and will finish with dry sand (I imagine that will pour easier). Much nicer than standard square bases.  Overall pleased and would recommend.