I was wondering the number of slots the Byron era (testnet) had or the slot number when Byron finished.

The only info I've been able to find is systemStart": "2019-07-24T20:20:16Z" coming from testnet-shelley-genesis.json.

( Calculate timestamp from slot discusses about the same thing but with mainnet Byron. )

Any help would be great. Thanks in advance!

  • Should you have accepted the answer?
    – gRebel
    Commented Mar 15, 2022 at 3:30
  • @gRebel right, done ✅
    – kindofdev
    Commented Mar 15, 2022 at 9:19

1 Answer 1


As far as I know, Shelley started at epoch 1, i.e. after a single Byron epoch 0 on Cardano Testnet.

Byron started on Testnet:

epoch 0 ... slot 1031 ... block 1 ... date 2019/07/25 ... time 02:03:56

Shelley started on Testnet:

epoch 1 ... slot 21600 ... block 20570 ... date 2019/07/29 ... time 20:20:16


There's also one simple way to check this out. Start downloading a Cardano Testnet DB onto your computer, and, at the very beginning of the process, apply cardano-cli command:

cardano-cli query tip --testnet

But the best solution is to send a request to the IOHK helpdesk.

  • So systemStart": "2019-07-24T20:20:16Z" coming from testnet-shelley-genesis.json, what does it mean?
    – kindofdev
    Commented Jan 30, 2022 at 20:25
  • I don't know what it means. Testnet explorer shows another date.
    – Andy Jazz
    Commented Jan 30, 2022 at 20:27
  • 1
    One more question if you're so kind. When was the slot duration set to 1 sec on Cardano Testnet? At the beginning of Shelley?
    – kindofdev
    Commented Jan 30, 2022 at 21:28
  • 1
    No problem, thank you for your help.
    – kindofdev
    Commented Jan 30, 2022 at 21:57
  • 1
    Travis found out when 1slot-1sec started, cardano.stackexchange.com/questions/6955/… @AndyJazz
    – kindofdev
    Commented Feb 2, 2022 at 0:32

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.