Block Emission | Mechanisms | Subtensor Reference

dTAO Emission Flow

dTAO Emission Flow (per block)

Step 1

~0.5 TAO / block

Logarithmic decay from 21M cap

Step 2

TAO Flow Shares

EMA of stake/unstake activity

Step 3: Liquidity Pools

TAO

reserves

Alpha

tokens

Alpha price = TAO in pool / Alpha in pool

More TAO staked → higher Alpha value

Inject TAO + mint Alpha for distribution

Step 4: Alpha Distribution (per subnet)

Owner Cut

taken first

remaining

Miners

50% of remainder

Validators

50% of remainder

Root Divs

if price > 1τ

Accumulates in Pending* storage until epoch

Step 5: At Epoch

Yuma Consensus

Distribute to wallets by I/D scores

I = incentive (miners) D = dividends (validators) τ = TAO

Example: Who Gets What (one block, one subnet)

0.5τ block emission → Subnet gets 20% share → 10% owner cut → α price = 1.0τ

TAO In: 0.10τ

Owner: 0.01α

Miners: 0.045α

Validators: 0.045α

0.10τ → 0.10α minted → 0.01α owner (10%) → 0.09α remainder → 50/50 split

Legacy Subnets (non-dTAO)

Subnets not yet on dTAO use root network weights for emission shares and distribute TAO directly without liquidity pools.

Key Storage Items

BlockEmission SubnetTaoFlow SubnetTAO SubnetAlphaIn SubnetMovingPrice PendingServerEmission PendingValidatorEmission

Click items to navigate to their reference pages.

The Big Picture

Block emission is the "money printer" of Bittensor. Every ~12 seconds a new block mints TAO from a 21M supply cap, and distributes it across all active subnets through their Alpha token pools. As more TAO has been minted, the emission rate decays logarithmically — like Bitcoin halving but smoother.

Why This Matters

Block emission determines the total new TAO entering the economy each day. It directly affects validator and miner earnings, Alpha token prices, and overall network inflation.

Example Scenario

At current issuance (~7.5M TAO of 21M cap), each block emits ~0.5 TAO. A subnet with 20% TAO Flow share receives 0.1 TAO per block. After 10% owner cut, the remaining 0.09 TAO worth of Alpha splits 50/50 between miners and validators — then distributed by Yuma Consensus at epoch.

Common Questions

When does emission stop?: Never fully — it decays asymptotically. Emission approaches zero as total issuance nears 21M TAO, similar to Bitcoin but with smoother logarithmic decay rather than discrete halvings.
How is emission split between subnets?: Via TAO Flow shares — an EMA of stake/unstake activity combined with root network validator weights. Subnets attracting more stake get more emission.

Use Cases

Estimating validator/miner daily earnings
Understanding network inflation rate
Modeling subnet economics
Planning long-term stake strategies

Every block, the Subtensor runtime mints new TAO and distributes it across subnets. The total emission per block is determined by the halving schedule (total issuance vs. max supply). Each subnet receives a share proportional to its TAO Flow allocation. Within each subnet, emissions are further split between validators and miners via Yuma Consensus results.

Since dTAO, emissions flow through Alpha token pools rather than being distributed as raw TAO.

Triggers

Every block (on_initialize hook)

Inputs (3)

Item	Type	Role
BlockEmission SubtensorModule	storage	TAO emitted per block (from halving schedule)
TotalIssuance SubtensorModule	storage	Current total TAO supply for halving calculation
NetworksAdded SubtensorModule	storage	Active subnet registry

Outputs (4)

Item	Type	Role
SubnetTAO SubtensorModule	storage	TAO injected into subnet Alpha pools each block via run_coinbase
SubnetAlphaIn SubtensorModule	storage	Alpha minted into subnet pools from emission injection
TotalIssuance SubtensorModule	storage	Updated total supply after minting
Emission SubtensorModule	storage	Per-UID emission amounts after epoch processing

Source Files

pallets/subtensor/src/coinbase/block_step.rs

block_step()

pallets/subtensor/src/coinbase/block_emission.rs

get_block_emission()

Formulas

Halving Schedule

Block emission decreases as total issuance approaches max supply (21M TAO), following a log2-based decay that halves emission at each issuance threshold.

residual = floor(log2(1 / (1 - total_issuance / (2 * 10_500_000_000_000_000))))
block_emission = DefaultBlockEmission / 2^residual
// DefaultBlockEmission = 1_000_000_000 RAO (1 TAO)
// Emission halves at each residual step as issuance grows

TypeScript: computeBlockEmission() in yuma-formulas.ts

Emission Calculator

See how block emission flows through subnets to participants

Block Emission (TAO)

= 500,000,000 RAO

Subnet Configuration

Subnet	TAO Flow %	Owner Cut %	Pool TAO	Pool Alpha	α Price	Actions
SN1					1.200τ
SN2					0.800τ
SN3					1.000τ

α Price auto-calculates from Pool TAO / Pool Alpha

Emission Breakdown (per block)

Subnet	TAO In	α Minted	Owner	Miners	Validators
SN1	0.2500τ	0.2083α	0.0208α (0.0250τ)	0.0938α (0.1125τ)	0.0938α (0.1125τ)
SN2	0.1500τ	0.1875α	0.009375α (0.007500τ)	0.0891α (0.0712τ)	0.0891α (0.0712τ)
SN3	0.1000τ	0.1000α	0.00e+0α (0.00e+0τ)	0.0500α (0.0500τ)	0.0500α (0.0500τ)
Total	0.5000τ		~0.0325τ	~0.2337τ	~0.2337τ

Your Position

Subnet

Role

Your Share of Incentive %

Your emission per block

0.009375α

≈ 0.0112 TAO value

Per hour (~300 blocks)

3.3750 TAO

Per day (~7,200 blocks)

81.0000 TAO

Flow: Block emission → divided by TAO Flow % → converted to Alpha at pool price → owner cut taken first → remainder split 50/50 between miners/validators.

Try: Change pool TAO to see how Alpha price affects the TAO-equivalent value. Higher-priced Alpha means each token is worth more TAO.

Read the deep dive: Block Emission

Version History

v101 Initial emission schedule with fixed block reward

v150 Halving schedule tied to total issuance

v200 Root network emission allocation introduced

v290 Emissions routed through Alpha token pools (dTAO)

v350 Owner cut taken before miner/validator split