The Mint Module

The x/mint module mints tokens at the end of epochs.

The x/distribution module is responsible for allocating tokens to stakers, community pool, etc.

The mint module uses time basis epochs from the x/epochs module.

The x/mint module is designed by Osmosis. It is used to handle the regular printing of new tokens within a chain. Its core function is to:

  • Mint new tokens once per epoch (default one week)
  • Have a "Reductioning factor" every period, which reduces the amount of rewards per epoch.
    (default: period is 3 years, where a year is 52 epochs. The next period's rewards are 2/3 of the prior period's rewards)


Minting params are held in the global params store.

type Params struct {
    MintDenom               string                  // type of coin to mint
    GenesisEpochProvisions  sdk.Dec                 // initial epoch provisions at genesis
    EpochIdentifier         string                  // identifier of epoch
    ReductionPeriodInEpochs int64                   // number of epochs between reward reductions
    ReductionFactor         sdk.Dec                 // reduction multiplier to execute on each period
 DistributionProportions DistributionProportions // distribution_proportions defines the proportion of the minted denom
 WeightedDeveloperRewardsReceivers    []WeightedAddress // address to receive developer rewards
 MintingRewardsDistributionStartEpoch int64             // start epoch to distribute minting rewards

The minting module contains the following parameters:

genesis_epoch_provisionsstring (dec)"500000000"
reduction_factorstring (dec)"0.6666666666666"
distribution_proportions.stakingstring (dec)"0.4"
distribution_proportions.pool_incentivesstring (dec)"0.3"
distribution_proportions.developer_rewardsstring (dec)"0.2"
distribution_proportions.community_poolstring (dec)"0.1"
weighted_developer_rewards_receiversarray[{"address": "osmoxx", "weight": "1"}]


Calculate the provisions generated for each epoch based on current epoch provisions. The provisions are then minted by the mint module's ModuleMinterAccount. These rewards are transferred to a FeeCollector, which handles distributing the rewards per the chains needs. (See for details) This fee collector is specified as the auth module's FeeCollector ModuleAccount.

func (m Minter) EpochProvision(params Params) sdk.Coin {
    provisionAmt := m.EpochProvisions.QuoInt(sdkmath.NewInt(int64(params.EpochsPerYear)))
    return sdk.NewCoin(params.MintDenom, provisionAmt.TruncateInt())


  1. mint_denom defines denom for minting token - uosmo
  2. genesis_epoch_provisions provides minting tokens per epoch at genesis.
  3. epoch_identifier defines the epoch identifier to be used for mint module e.g. "weekly"
  4. reduction_period_in_epochs defines the number of epochs to pass to reduce mint amount
  5. reduction_factor defines the reduction factor of tokens at every reduction_period_in_epochs
  6. distribution_proportions defines distribution rules for minted tokens, when developer rewards address is empty, it distributes tokens to community pool.
  7. weighted_developer_rewards_receivers provides the addresses that receives developer rewards by weight
  8. minting_rewards_distribution_start_epoch defines the start epoch of minting to make sure minting start after initial pools are set


Minting parameters are recalculated and inflation
paid at the beginning of each epoch. An epoch is signalled by x/epochs


The target epoch provision is recalculated on each reduction period (default 3 years).
At the time of reduction, the current provision is multiplied by reduction factor (default 2/3),
to calculate the provisions for the next epoch. Consequently, the rewards of the next period
will be lowered by 1 - reduction factor.

func (m Minter) NextEpochProvisions(params Params) sdk.Dec {
    return m.EpochProvisions.Mul(params.ReductionFactor)

Reductioning factor

This is a generalization over the Bitcoin style halvenings.
Every year, the amount of rewards issued per week will reduce by a governance specified factor, instead of a fixed 1/2.
So RewardsPerEpochNextPeriod = ReductionFactor * CurrentRewardsPerEpoch).
When ReductionFactor = 1/2, the Bitcoin halvenings are recreated.
We default to having a reduction factor of 2/3, and thus reduce rewards at the end of every year by 33%.

The implication of this is that the total supply is finite, according to the following formula:

$$Total\ Supply = InitialSupply + EpochsPerPeriod * \frac{InitialRewardsPerEpoch}{1 - ReductionFactor} $$


The minting module emits the following events:

End of Epoch

TypeAttribute KeyAttribute Value


The minter is a space for holding current rewards information.

type Minter struct {
    EpochProvisions sdk.Dec   // Rewards for the current epoch