March 2020 MAU
According to RTrack analytics, Roblox hit 134M+ MAU in March of 2020. In January, RTrack data showed a MAU of 119M+ users in the 30 days preceding January 31st 2019, meaning an increase of around 15 million users in just 2 months, likely attributable to the coronavirus. Shown below is data from an August 2019 Business Insider article  and RTrack’s most recent data.
This hints at strong user growth for Roblox in terms of monthly active users, with a large jump in players.
RTrack’s value for March 2020 MAU is an estimate based on a randomly selected sample of 30,005 Roblox accounts, of which 2,639 were found to have been online in the past 31 days. At the time of calculating, total Roblox acccounts were estimated to total 1.53 billion, using the percentage of the sample online (8.7%), total monthly active users were estimated to be between 134 and 135 million. This process was allowed to run four times with a different sample group, with MAU falling between 134 and 135 million each time.
RTrack does not make any claims as to the validity or accuracy of the values shown in this blog post, and is not associated with Roblox Corp. These values are not official Roblox figures and were not released by Roblox Corp.
 “Roblox has eclipsed Minecraft with 100 million users — highlighting the popularity of ‘digital hangouts'” As of 1st April 2020: https://www.businessinsider.com/roblox-user-growth-surpasses-minecraft-2019-8?r=US&IR=T