Issue 048 - Advertising technology - Internet-scale auction throughput
How many online ad auctions does Google run every second?
On September 2, a federal judge rejected the U.S. government's attempt to force Google to sell its AdX advertising exchange, the fast auction system that connects publishers selling ad space with advertisers bidding for it.
The problem
Estimate approximately how many online advertising auctions Google AdX might conduct every second worldwide.
Then estimate the approximate dollar value of advertising being sold through those auctions each day, and Google's potential share of that value from its fee.
You'll need to estimate regular web users, page loads per user, ads per page, Google's share of the ad-tech flow, and the average value of an individual ad impression.
Because Fermi problems target an order of magnitude, I normally use no more than two significant digits and write most calculations in scientific notation; the Fermi reference explains both conventions.
Before checking sources
Matt's first pass
I had to make a lot of guesses, and I was not sure how strong any of them were.
I assumed about 80% of the world's population are regular internet users, and that they average 10 sites visited by links daily. If there are about 8 billion people, then 80% of them is about 6.4 billion people.
internet users ~= 0.8 x 8 x 10^9 people
~= 6.4 x 10^9 users
site visits/day ~= 6.4 x 10^9 users x 10 visits/user/day
~= 6.4 x 10^10 visits/dayThere are 1,440 minutes in a day, so a day has about 8.6 x 10^4 seconds. Dividing daily site visits by seconds in a day:
visits/second ~= 6.4 x 10^10 visits/day / 8.6 x 10^4 seconds/day
~= 7.4 x 10^5 visits/secondI assumed 70% of those visits are coordinated by Google's AdX, which gives about 5.2 x 10^5 AdX page visits per second. Then I assumed 3 ads per site on average.
AdX ad opportunities/second
~= 5.2 x 10^5 page visits/second x 3 ads/page
~= 1.6 x 10^6 auctions/secondFor value, I guessed about 1 cent per ad impression.
gross ad value/second ~= 1.6 x 10^6 ads/second x $0.01/ad
~= $1.6 x 10^4/second
Google share at 20% ~= $3.2 x 10^3/second
annual Google share ~= $3.2 x 10^3/second x 3.2 x 10^7 seconds/year
~= $1.0 x 10^11/yearThat works out to about $100 billion per year in ad revenues going to Google from AdX.
Calibration Score
Matt's Calibration Score: 60 / 100
Higher is better: earn points for accurate pegs, sound models, correct math, and a result close to the sourced answer. The image shows percent full of it: 100 minus the Calibration Score.
Pegs: 10/30. Internet-user share was strong, but page activity, ad-request density, Google-touch share, and impression value were fuzzy enough to pull the result around by large factors.
Model: 30/30. Users times pages times ad opportunities times market share is the right basic model for a bottom-up estimate.
Math: 10/10. The arithmetic was basically clean given the assumptions.
Result: 10/30. The auction/request count was low by more than one order of magnitude, while the annual Google-dollar estimate was high but still in the right broad business-scale neighborhood.
Grounding facts
ITU estimated that about 6 billion people, or roughly 74% of the world's population, used the internet in 2025. DataReportal's April 2026 update put the figure around 6.1 billion, or about 74%.
AP's coverage of the Google ad-tech remedies reported that Google said the advertising-exchange technology targeted in the case handles about 55 million requests per second. That is the best direct reality check for the auction-throughput side of the problem.
Alphabet's Q1 2026 results reported $6.971 billion in quarterly Google Network revenue. Annualized, that is about $28 billion/year. Google Network includes properties participating in AdMob, AdSense, and Google Ad Manager, so it is not a pure AdX-only number, but it is a useful size check.
After checking sources
Check and recalibrate
The direct throughput check is much larger than Matt's page-load model:
reported ad-tech requests ~= 5.5 x 10^7 requests/second
seconds/day ~= 8.6 x 10^4
requests/day ~= 5.5 x 10^7 x 8.6 x 10^4
~= 4.7 x 10^12 requests/daySo the cleaner scale answer is tens of millions of ad requests per second, not one or two million. The page-load model probably undercounts because ad systems handle mobile apps, multiple ad slots, refreshes, retries, auctions involving many bidders, and requests that do not become paid impressions.
For the dollar side, use Alphabet's network-ad revenue as a reality check. If roughly $28 billion/year is Google's recognized network revenue, and if a 20% exchange fee is the right simplifying take rate, then the implied gross ad value is:
Google share ~= $2.8 x 10^10/year
fee ~= 0.20
gross ad value ~= $2.8 x 10^10 / 0.20
~= $1.4 x 10^11/year
gross value/day ~= $1.4 x 10^11 / 365
~= $4 x 10^8/day
Google share/day ~= $8 x 10^7/dayThat suggests the marketplace is plausibly on the order of hundreds of millions of dollars in ad value per day, with Google's share in the tens of millions of dollars per day and tens of billions per year. The exact AdX-only number may be lower than the full Google Network line, but the scale is absolutely not a small back-office fee stream.
The implied value per request is tiny:
gross value/request
~= $4 x 10^8/day / 4.7 x 10^12 requests/day
~= $8 x 10^-5/requestThat is about eight thousandths of a cent per request, or roughly $0.08 CPM if counted across every request. That low average makes sense if many requests are low-value, unsold, duplicated, refreshed, or not equivalent to one final paid impression.
Post-check reflection
Matt's reflection
I did pretty well on total internet users worldwide: 80% is close to the 74% reference number, so that part of my mental model was good.
Ten sites per day might be low, but it is hard to say. Some internet activity happens for hours on a single site, like YouTube or TikTok, while shopping or trip planning might involve hundreds of page visits in an hour. I still think 10 is a fair rough estimate.
I was fuzzy on where the AdX touch comes in, but I do not think that changes the ultimate structure of the calculation. My estimated count of AdX opportunities was low compared with the reported request scale, but the model was pointing in the right direction.
Ads per page was iffy, but my big error was cost per ad. I did not think to convert a cent per ad into CPM-style ad pricing, and that pushed my answer up by at least an order of magnitude.
Still, this is an absurd amount of revenue annually, and it is still probably a single-digit percentage of Google's total revenue depending on how much of the broader Google Network line is really AdX.
Recommended memory peg
For online-ad problems, remember about 6 billion people use the internet, a day has 8.6 x 10^4 seconds, and large ad exchanges can process around 10^7 to 10^8 ad requests per second. Ad prices are often easier to think about as CPM: $1 CPM = $0.001 per impression.
Reader results
Bars show how submitted estimates sort into the answer choices from the gut-check prompt.