How to Read Your Kitty’s Genes

You can use this spreadsheet to read your kitty’s genes for you. Read below to understand how it works.

Find and Read Your Kitty’s Genetic Code

1.  Your kitty’s genome is made up of gene blocks. Each block of 4 genes describes a cattribute category. Your kitty has 1 dominant trait and 3 recessive traits in each group. The dominant trait (D0) is on the right side and is your kitty’s visible cattribute (e.g. sphynx). The recessive traits are non-visible, but may be passed on to children.

kai genome2.  Kittens have a 75% chance of inheriting the dominant trait from one of their parents, and a 25% chance of inheriting one of their parents’ recessive genes. (For detailed odds, see my post on Breeding Outcomes.)

The Trait Chart has all known traits and their kai and binary codes.

This spreadsheet will read your kitty’s genes for you.

Special shout-out to kai for breaking the genetic code. See his article here:


Gas Limit and Gas Price

metamaskWhat is gas limit and gas price?

Every action in CryptoKitties goes to the ethereum network where miners execute the transaction. The price you pay for their services is the “Tx fee” (transaction fee). It is made up of two parts: Gas Price and Gas Limit.

  • Gas Price (GWEI) is what you offer to pay the miners for each operation they do to execute the smart contract.
  • Gas Limit is how many operations you allow them to do before they “run out of gas” and drop the transaction.

Read More »

How much does it cost to play CryptoKitties?

Here are all the costs you might encounter while playing CryptoKitties.


Buying a cat.  (Price varies.)
Hiring a sire for your cat.  (Price varies.)
Breeding.  (0.008 ETH)*
Sales fee. When you successfully sell or sire a cat, 3.75% of the sale goes to developers.
Transaction fees (gas)*. Every time you perform an action, you have to pay the ethereum miners to complete the task. The gas fee is shown before you submit a transaction. It is roughly between $0.30 – $3.00 (depending on ethereum network traffic).

* The breeding fee was initially 0.001 ETH. It had to be raised due to the mechanics of how kittens are “born” (the breeding fee has to be higher than gas fees). The breeding fee may drop back down once the ethereum network can handle a large volume of transactions.
* Gas fees high right now due to the volume of transactions on the blockchain. These should go down dramatically once ethereum scales.

Happy Kittying!
– Jodiferous

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How to Breed Cats Using the Smart Contract (MEW)

Cats being stuck with “Bun in Oven” or “Resting” is a common issue, and it will generally resolve itself within a few hours. But in case you don’t want to wait, you can call the smart contract manually using MyEtherWallet.

Breeding with Smart Contract (MEW)

UPDATE: They have removed the CryptoKitties contract from MEW. You can copy the ABI from here:

STEP 0: Make sure your cats are ready to breed or the transaction will fail. (Click on the link in step 3 and enter the kitty IDs individually on line 29 “isReadyToBreed” and click on Query to check.)

1. Go to
2. Click on the Contracts tab.
3. Select the CryptoKitties smart contract (the address should match
4. Click Access.
5. Select the breedWithAuto function.
6. Input the kitty IDs of your matron and sire.
7. Select Metamask as your sending option in the bottom. Click Connect to Metamask.
8. Press Write and enter in the breeding fee (currently 0.008 at the time of this post, this breeding fee can change) as the sending value in the popup.
9. Send the transaction and in the Metamask popup, enter your gas price. (See for current gas prices.)

Once your transaction is successful, the matron of the breeding pair should have a new Bun in the Oven. Happy breeding!

Here is a video walk-through of the process provided by LucyintheSky:

breed with MEW 1

breed with MEW 2

breed with MEW 3

Courtesy of DERPYBASTARD and anyone else who contributed to this how-to guide.