Ned Segal
Chief Financial Officer at Twitter
Thanks, Jack. Q3 was a solid quarter driven by focus and execution. Total revenue grew 37% year-over-year at the high end of our guidance. mDAU grew 13% year-over-year to $211 million, with US mDAU essentially flat quarter-over-quarter, and up 4% year-over-year, both in line with our expectations. Due to the unusual comps from the pandemic surge last year, coupled with typical seasonality. We expect total mDAU in Q4 to grow at or above the Q3 rate of 13% on a year-over-year basis. And we continue to believe the low point for year-over-year mDAU growth, in 2021 was back up Q2 due to those tough comps.
The impact of COVID remains fragmented across the world, and we believe consumer behavior has yet to normalize. Despite these uncertainties, we remain optimistic given our healthy top of funnel, our conversion rate and our product roadmap, which allow us to serve more and more people every day. Let me share some of the highlights from the Olympics on our DR Roadmap from Q3. The Olympics were a strong event for us. Olympics-related tweets of video content reviewed more than 1 billion times on Twitter.
There were 76 billion tweet impressions related to the Olympics. And 12 of the 14 official Olympics sponsors advertised on Twitter. Our shift to direct response ads also made great strides. For math advertisers, we launched an updated learning period model that delivers more consistent campaign performance. And for website clicks, we introduced a multi destination CareSouth, to enable advertisers to market and drive traffic to multiple products inside the same ad on Twitter.
These are just a few examples of our accelerated pace of testing and rolling out new features, yet we won't stop there when it comes to increasing focus on our most critical work. As Jack mentioned earlier, and although it happened in October, it's worth spending a moment on the announced sale of MoPub. The sale of MoPub positions us to reallocate resources and accelerate product development by investing more and the team's focused on better monetizing our website and apps.
The sale is expected to close in Q1, and while the associated product engineering and go-to-market teams are largely expected to shift to DR, SMB and commerce upon closing, it will take time for their work to deliver results. We do not expect to recoup the full revenue loss associated with the sale of MoPub in 2022. Which is estimated to be between $200 million and $250 million.
Despite some expected 2022 revenue loss, there are no changes to our goal of generating $7.5 billion or more of annual revenue in 2023, with our increased focus and additional resources working on increasing our market share. And the $150 billion and growing addressable market for ads on Twitter. I've also noticed there has been a lot of focus more broadly on the impact of the supply chain on the economy in general and advertising in particular. I'm pleased to share that are launching connect value proposition, continues to resonate with advertisers across the economy.
Both well, more than half of our total ad revenue year-to-date, associated with services and digital goods. Let me also spend a moment on ATT. We continue to see opportunities around personalization on Twitter as we better leverage our unique signal to improve people's experienced. And show them more effective Ads across both brand and direct response. The revenue impact we experienced from ATT in Q3 increased on a sequential basis, but remains modest. The impact of ATT is likely to vary across ad platforms given the unique mix of ad formats, signal, and remediations on each, as well as other factors.
The mitigations we've put in place and the speed with which we've adopted new standards, like SKAdNetwork and resulting changes across our technical stack have contributed to minimizing the impact to us. Since the launch of ATT April, we've invested in supporting SKAdNetwork, opening up 30% plus more inventory and scale on iOS, and launched support for view through attribution and FK campaign ID management features in the Twitter
Ads Manager. It's still too early for Twitter to assess the long-term impact of Apple's privacy-related iOS changes, but the Q3 revenue impact was lower than expected, and we've incorporated an ongoing modest impact into our Q4 guidance. We've seen our revenue product development, both related to and distinct from ATT, improve the performance of our products, and we expect that to continue. Let me quickly turn to a couple of points regarding our outlook. We continue to expect total revenue to grow faster than expenses in 2021, excluding the litigation settlement announced in Q3.
And we expect to continue our investment posture as we enter next year. We'll talk more about 2022 in February. but let me provide a little more context here. Our 30% plus headcount growth in 2021 with annual metric increases and other investments we've made in 2021, including our new data center, will flow into annual expenses for 2022, likely resulting in a mid-20% increase in total expenses next year prior to hiring any more people or additional investments during 2022.
We're pleased with our Q3 results and we're excited about the momentum we bring with us into Q4. Let's go to questions.