On November 10, 2021, it was reported that the album had gained over 630,000 pre-order sales by November 8, becoming Twice’s most pre-ordered and best-selling album of all-time before its release.By November 10, it had reached over 700,000 pre-order sales. In its first week, MRC Data reported that the album had sold 66,000 album-equivalent units in the United States. Of these, 58,000 were pure sales, 8,000 were streaming-equivalent units, and a negligible amount were track-equivalent units.

Formula of Love: O+T=<3 debuted at number 1 in South Korea’s Gaon Album Chart, making it Twice’s tenth number-one album on the chart, following More & More (2020). In Japan, it peaked at number 17 on Billboard Japan‘s Hot Albums chart and at number 2 on Oricon’s Albums Chart. The album became Twice’s highest-charting album in the US and Canada to date, peaking at number 3 on the Billboard 200 and at number 17 on the Canadian Albums Chart. On Billboard, it charted atop the Tastemakers, Top Album Sales, and World Albums charts,peaking at numbers 7, 2, and 1, respectively. In Europe, the album appeared in Belgium’s Ultratop Flanders and Wallonia 200 Albums, Finland’s Top 50 Albums, Lithuania’s Top 100 Albums,the Netherlands’ Album Top 100, and the United Kingdom’s Album Downloads Chart.