Polkadot SRB

Learn how Polkadot staking rewards are calculated. DOTSRB formula covers era validator rewards, total staked DOT, annualization, and NPoS commission model.

DOTSRB is a benchmark representing the annualized staking rate for the DOT token.

DOTSRB is calculated and published by Staking Rewards via the Polkadot Profile and Data API.

TL;DR: Polkadot staking rewards are derived from actual on-chain era rewards, not inflation estimates. The reward rate equals era validator rewards annualized over 365 days divided by total staked DOT. Validator-level rates are adjusted by commission using the era-based Nominated Proof of Stake model.

DOT Staking Rewards Rate: DOTSRB

$$DOTSRB = evr * t_y / st$$

Formula Key	Metric Name	Description
evr	Era Validator Reward	The total reward distributed to all validators for the previous era, sourced directly from on-chain storage.
st	Staked Tokens	The total staked DOT in the active era, sourced from on-chain era total stake.
$t_y$	Year Constant	365d — used to annualize the per-era reward.

• DOTSRB is non-compounded, excluding returns from reinvestment of rewards.

• The reward rate is derived from actual on-chain era rewards, not from an inflation model estimate.

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DOT Validator Staking Rewards Rate: DOTSRB(v)

Staking Rewards calculates the DOTSRB for each validator based on their individual commission rate.

$$DOTSRB(v) = DOTSRB * (1 - c)$$

Formula key	Metric Name	Description
c	Commission	The fee imposed by a specific validator to its delegators.

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Observation Period:

1. The DOTSRB is determined based on the latest completed era at the evaluation point.

2. This data is then annualized for a comprehensive year-long projection.

Calculation

The calculation happens every 6 hours and is immediately published via Data API.

Limitations

1. DOTSRB employs a 365-day convention for annualizing era reward data. This convention remains consistent and does not accommodate adjustments for leap years.

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DOT Real Reward Rate: DOTSRB^R

The real reward rate calculates the reward rate adjusted for inflation in the network.

$$DOTSRB^R = 1+DOTSRB/(1+ir)-1$$

Formula key	Metric name	Description
ir	Inflation Rate	Derived from on-chain era rewards: eraValidatorReward * 365 / totalSupply.

Inflation Rate Behavior

• Since March 2026, Polkadot has a capped supply model with a maximum of 2.1 billion DOT. The emission follows a stepped curve that reduces approximately every 2 years, starting at roughly 13.14% of the remaining supply per step. This replaced the previous fixed 120M DOT/year expansion model. The inflation rate is derived from actual on-chain era rewards, making it self-correcting as the emission schedule progresses.

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Other Polkadot metrics calculated by Staking Rewards:

Metric	Description
Delegated Tokens	The number of DOT tokens delegated to validators (nominators' stake).
Self Staked Tokens	The number of DOT tokens staked by validators directly (stash bonded amount).
Staking Wallets	Total number of nominators on-chain.

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Data Sources:

• Polkadot Substrate RPC (on-chain staking pallet queries via py-substrate-interface)

• CoinGecko for price and circulating supply

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References:

• Polkadot Staking Docs

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⚙️ Access historic DOT Staking Data via API

Last updated on 03/16/2026