SUBMIT A PR SUBMIT AN ISSUElast edit: Aug 12, 2025

Transaction Fees in Bittensor

This page describes the blockchain transaction fees charged by Bittensor.

Many extrinsic transactions that change the state of the blockchain are subject to a flat fee of approximately 0.0013 $\tau$ .

Staking and unstaking operations incur weight-based fees as well as amount-based fees of 0.05% of the transacted liquidity.

Reading the state of the chain is always free.

Weight-Based Transaction Fees

Many extrinsics in Bittensor are subject to a flat weight-based fee. In Polkadot-based chains like Subtensor (Bittensor's layer 1 blockchain), weight is a measure of compute time.

Fee Details:

Current rate: $\approx0.0013 \tau$
Payment source: Free balance of the transaction sender
Denomination: TAO
Impact on liquidity: Fees are recycled (deducted from TotalIssuance) See: Recycling and Burning

Planned reduction

It is currently planned that the fee coefficient will be reduced to $0.005%$ (10x reduction).

Staking Operations

Wallet and Identity Management

Subnet Management

Burn/recycle alpha

Child Hotkey Management

Governance

adjust_senate

See how it's calculated!

pub struct LinearWeightToFee;

impl WeightToFeePolynomial for LinearWeightToFee {
    type Balance = Balance;

    fn polynomial() -> WeightToFeeCoefficients<Self::Balance> {
        let coefficient = WeightToFeeCoefficient {
            coeff_integer: 0,
            coeff_frac: Perbill::from_parts(500_000), // 0.05%
            negative: false,
            degree: 1,
        };
        smallvec!(coefficient)
    }
}

Source code reference: runtime/src/lib.rs:448-463

Swap Fees for Stake and Unstake Operations

In addition to the weight-based fee above, staking and unstaking operations are subject to fees based on a percentage of the quantity of transacted liquidity.

Fee Details:

Rate: 0.05%
For staking: Fee paid in TAO from the staking amount
For unstaking: Fee paid in Alpha from the unstaking amount

Example

btcli stake add 

...

Amount to stake (TAO τ): 100

                                                       Staking to:
                   Wallet: 2MuchTau!, Coldkey ss58: 5Xj...
                                                      Network: test

        ┃              ┃            ┃              ┃              ┃          ┃              ┃  Rate with   ┃   Partial
        ┃              ┃            ┃              ┃     Est.     ┃          ┃  Extrinsic   ┃  tolerance:  ┃    stake
 Netuid ┃    Hotkey    ┃ Amount (τ) ┃ Rate (per τ) ┃   Received   ┃ Fee (τ)  ┃   Fee (τ)    ┃    (0.5%)    ┃   enabled
━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━
   2    │ 5GrwvaEF5zX… │ 100.0000 τ │ 2416.813286… │ 241,556.4147 │ Τ 0.0504 │   0.0013 τ   │  2404.7893   │    False
        │              │            │     β/Τ      │      β       │          │              │     β/Τ      │
────────┼──────────────┼────────────┼──────────────┼──────────────┼──────────┼──────────────┼──────────────┼──────────────
        │              │            │              │              │          │              │              │

Source code references:

Fee-Free Extrinsics

The following extrinsics are free.

Weight Setting & Commit-Reveal

set_weights - Setting validator weights
commit_weights - Commit weight hash
batch_commit_weights - Batch commit weight hashes
reveal_weights - Reveal committed weights
commit_crv3_weights - Commit CRv3 encrypted weights
batch_reveal_weights - Batch reveal committed weights

Administrative & Operational

Sudo and admin extrinsics
Governance-related functions

Weight-Based Transaction Fees​

Staking Operations​

Wallet and Identity Management​

Subnet Management​

Burn/recycle alpha​

Child Hotkey Management​

Governance​

Swap Fees for Stake and Unstake Operations​

Example​

Fee-Free Extrinsics​

Weight Setting & Commit-Reveal​

Administrative & Operational​