Ad mediation and bidding

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Many networks, one ad

Theo adds rewarded ads for adult players: watch a short video, get a seed. Many ad networks want to fill each one. Mediation asks several of them, so each ad goes to the one that pays the most.

eCPM

Ad money is counted as eCPM: what the studio earns for every 1,000 ads shown. An eCPM of US$12 means US$12 for 1,000 ads, or 1.2 cents for one.

Do the math

rewarded ads
ads a day  200,000eCPM       US$12

How much does Theo expect the ads to earn a day?

  1. US$2,400
  2. US$24
  3. US$240,000
Show the answer

US$2,400

200,000 ads is 200 thousands, and each thousand earns US$12: 200 × US$12 = US$2,400.

The waterfall

Older mediation is a waterfall. Google AdMob describes it as relying "on user-provided eCPM or historical data to prioritize networks and call them one at a time". The first network to say yes shows the ad.

Bidding

AdMob: "Bidding enables ad sources to compete in a real-time auction to fill your ad requests." Unlike the waterfall, "bidding calls all participating ad sources simultaneously." The winning bid is then "placed in the mediation waterfall according to the eCPM value."

Quick check

Theo's waterfall asks Network A first, because it paid US$10 last month. Today Network B would pay US$13 for this ad. In a waterfall, who shows it?

  1. Network A, at US$10
  2. Network B, at US$13
  3. Nobody
Show the answer

Network A, at US$10

A waterfall stops at the first yes, in the order of past prices. Bidding asks every source at once, so B's US$13 would win there.

Children's ads are different

AdMob: "bidding ad sources do not support ad serving for child-directed apps or ad requests." Remy marks every ad request from a player under 13 as child-directed, so only waterfall sources can fill it, under the rules for children's ads.

Quick check

Why does a 10-year-old's ad request carry the child-directed mark?

  1. Children's ads have their own rules, and bidding sources don't serve them
  2. It earns more money
  3. It makes the ad longer
Show the answer

Children's ads have their own rules, and bidding sources don't serve them

The mark tells every ad source the player is a child. AdMob's bidding sources don't serve those requests at all.

Quick check

A waterfall always gets the highest price available for each ad.

Show the answer

False

It takes the first yes, in the order of past eCPMs. Today's best offer can be further down.

Random items

One kind of item needs the most care: a prize you can't see before you pay.

Bolt says: Next: loot boxes and the law.

Fact-checked 12 October 2026