Epochs & Slots
How time is measured and organized on the Cardano blockchain.
Measuring Time in Cardano
A blockchain requires a precise clock to chronologically order transactions and reach consensus. In Cardano, time is not simply viewed as a continuous flow, but is divided into fixed periods: Epochs and Slots. This system is heavily oriented towards traditional calendars to make calculations predictable and secure.
What is a Slot?
A slot is the smallest unit of time within the Cardano ledger. In the current network configuration, exactly 1 Slot = 1 Second. In each of these slots, the network theoretically has the opportunity to produce a new data block. However, a block is not generated in every slot; the system is configured (via the 'Active Slot Coefficient' parameter) so that a new block is created roughly every 20 seconds on average.
What is an Epoch?
An Epoch is a collection of many slots. Currently, a Cardano epoch consists of exactly 432,000 slots, which equates to exactly 5 days. Epochs are extremely important cycles for the network:
- Staking Boundaries: At the boundaries between two epochs (epoch transition), snapshots of the network are taken to determine who has delegated how much ADA to which pool.
- Rewards Distribution: Staking rewards are always calculated per epoch and distributed at the beginning of subsequent cycles.
- Governance & Parameters: Changes to network parameters or governance decisions typically take effect at epoch boundaries.
In short: Slots structure the heartbeat (ticking) for block production, while epochs dictate the overarching rhythm for staking, rewards, and governance.