In Zoo Tycoon the smaller rocks tend to get the animals happier because they are a fraction of a large rock and can hit their rock requirement without going over. However they are expensive.

What is cost effective, some large rocks, or many small rocks?

  • Which zoo tycoon? The original?
    – Waterseas
    May 1, 2014 at 17:25
  • @Waterseas Yes the first one.
    – Peter V.
    May 1, 2014 at 17:27
  • 1
    I would imagine that the most cost effective solution would be to use large ones until you go over, then delete some large rocks and finish the job with small rocks. May 2, 2014 at 17:10
  • IIRC small rocks give the same amount of happiness as big rocks while costing $20 less, so it's more cost-effective to get small rocks. If you wanted to test, I'd start a new zoo, get two identical exhibits going, then do one with big rocks and one with small, calculating the final cost to reach the same amount of happiness. Should only take like 10 minutes.
    – zpletan
    Jul 3, 2014 at 16:48

1 Answer 1


How Zoo Tycoon handles rocks is a little odd. Small and medium rocks both satisfy the same amount of animal happiness. For example, a mountain lion in a certain sized exhibit will be happy with up to 40 small rocks (after that it will start displaying sad faces). The same goes for medium rocks. However, the game counts large rocks as the equivalent of 4 small/medium rocks. So 10 large rocks will fulfill the requirement.

Small rocks cost $55 a piece. Four of those together cost $220. One large rock (the equivalent of four small rocks) costs $150.

So to be the most cost effective, use just large rocks until the animal stops making happy faces. Then delete the last large rock and begin placing small rocks. If after 1 - 3 it stops making smiley faces, keep the small rocks. If after exactly 4 small rocks it stops the smilies, replace them with one large rock. Just never use medium rocks!

Here's the experimentation I did with multiple different exhibits if you want to watch it for proof:

  • the video was unlisted
    – Nick S
    Jul 11, 2018 at 20:04
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    Oops, I think my computer went to sleep while uploading the video and it interrupted the video upload halfway through. I'll try and re-upload it in a couple of days when I get the chance.
    – Guy
    Jul 14, 2018 at 6:17

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