How did we arrive at 13 billion pixels? By Sean Heber Since we (sadly) don't have a complete archive of all of our work ever, we had to come up with a total pixel count using an approximation technique. We ended up using what is often referred to as a Fermi estimate (https://en.wikipedia.org/wiki/Fermi_problem) to arrive at a total based on multiple estimates of multiple projects and time periods. See also: https://en.wikipedia.org/wiki/Hand-waving We split the last 20 years up into several pixel-size-based "eras" and then multiplied the number of client projects along with their average sizes during that time period. Here's the raw data: Old School Mac (16x16 + 32x32 = 1280px): 150 sets 25 icons each = 4800000px Pre-Retina Mac Sets (16+32+48+128 = 19968px): 100 sets 15 icons each = 30336000px Retina Mac Sets (1398016px): 50 sets 12 icons each = 838809600px Old School Client "sets" (16x16 + 32x32 = 1280px): 250 sets 25 icons each = 8000000px Pre-Retina Mac Client sets (16+32+48+128 = 19968px): 140 sets 15 icons each = 41932800px Pre-Retina Mac MEGA Client sets (16+32+48+128 = 19968px): 10 sets 500 icons each = 99840000px Retina Mac Client sets (1398016px): 400 sets 15 icons each = 8388096000px Pre-Retina iOS Internal Projects (1107446px per set) 4 "sets" 150 icons each (rough guesses) = 664467600px Pre-retina iOS client projects (1107446px per set) 150 sets 10 each = 1661169000px Retina iOS client projects (1140061px per set) 75 sets 8 each = 684036600px Retina iOS Projects (1140061px per set) 4 sets 30 each = 136807320px Windows XP 150 icons = 11836800px Windows Vista 100 icons = 7891200px Twitter emoji 1000 icons @ 16x16 and 72x72 800 @ 72x72 = 9587200px Facebook emoji 1200 icons 2 sizes = 512x512, 72x72 = 267328 = 320793600px The grand total of these numbers is 12,908,403,720px which we rounded up to 13 billion since it's close and we likely missed or forgot entire projects along with large UI-based design projects, background images, etc.