What is an epoch?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 4 min
In short
An epoch is a fixed span grouping many blocks or slots. Validator assignment, reward accounting and finality decisions happen per epoch rather than per block. The length differs by chain: 32 slots on Ethereum, five days on Cardano.
Key points
- A grouping of many slots or blocks into one period
- The unit for validator assignment and reward accounting
- On Ethereum it is 32 slots, about 6.4 minutes
- Length and purpose vary widely between chains
Definition
A unit of time in proof-of-stake chains covering a fixed number of slots or blocks, used as the boundary for assigning roles and tallying results.
Recomputing every validator's duties for each block would be wasteful and would make vote tallying awkward. Chains therefore group a fixed number of blocks into a period and decide within it who proposes when and who sits on which committee. That period is the epoch.
On Ethereum, 32 twelve-second slots make one epoch — about six minutes and twenty-four seconds. Each validator is assigned one attestation per epoch. Finality is judged at epoch boundaries and normally arrives two epochs later, so a block takes roughly thirteen minutes to finalise.
Cardano's epoch is five days, and delegation changes and staking rewards are settled on that cycle, which is why switching pools takes several epochs to show up in rewards. Solana defines its epochs by slot count, landing around two to three days. The same word, quite different designs.
Watch out for
- · Delegations and exits take effect at epoch boundaries, not the moment you submit them
- · Rewards are accounted per epoch, so unstaking mid-epoch can forfeit what you expected
- · Epoch length varies by chain — do not estimate waiting times from another chain's schedule