List of most massive star clusters

Below are lists of the most massive known star clusters in solar masses and sorted in descending order.

Globular cluster
Globular cluster masses can be determined by observing the proper motion of nearby stars influenced by the cluster or by estimating the cluster's relaxation time.

Open clusters
The masses of open star clusters can be estimated by measuring the falloff of radial and tangential velocities of surrounding stars at a particular distance.