Bitcoin Core 29.1 May Cut Default Relay Fee to 0.1 sat/vB and Lower Transaction Costs

• Default fee reduced from 1 sat/vB to 0.1 sat/vB — a 90% reduction

• Most node operators can change the setting, so full network effect depends on adoption pace

• Current node telemetry: Bitcoin Core 29 and Knots versions show mixed uptake; only a small share run 29.1

Bitcoin Core 29.1 cuts the minimum relay fee to 0.1 sat/vB, slashing fees 90%. Read how this impacts transaction costs, node operators, and network propagation — learn what to expect.

Bitcoin Core 29.1 cut the default minimum relay fee from 1 sat/vB to 0.1 sat/vB, making Bitcoin transactions significantly cheaper while retaining DoS protection.

What is the Bitcoin Core 29.1 minimum relay fee change?

Bitcoin Core 29.1 sets the default minimum relay fee to 0.1 sat/vB (100 sat/kvB), down from 1 sat/vB. This 90% reduction lowers the default threshold below which nodes will generally not relay transactions, making many low-fee transactions more likely to propagate.

How will the reduced minimum relay fee affect transaction costs and propagation?

The change reduces the default relay floor, so transactions priced between 0.1 and 1 sat/vB are now more likely to be accepted by nodes running the new default. Miners and node operators still control what they relay and mine. Data shows many sub-1 sat/vB transactions were already being mined, and the new default aligns node behavior with observed miner acceptance.

When will nodes adopt Bitcoin Core 29.1?

Adoption will be incremental. BitRef telemetry indicates that over 72.5% of nodes run Bitcoin Core software, but only a small fraction currently run Bitcoin Core 29.1.

Current node snapshot: Bitcoin Core 29 shows strong presence with 4,510 nodes (~18% of network), Bitcoin Core 28.1 accounts for 3,991 nodes (~16%), and Bitcoin Knots 29.1 runs on 3,083 nodes (~12.3%). Only 571 nodes reported Bitcoin Core 29.1 (≈2.3%). These figures imply a gradual rollout as operators update.

Bitcoin Knots raises the Bitcoin Core default minimum relay fee tenfold to maintain the old value. Source: GitHub

Why did developers lower the default fee?

Developers cited long-term BTC price changes and observed network behavior. The decision, taken by Bitcoin Core contributors on Aug. 15, notes that the minimum relay fee is primarily a DoS protection rule. With BTC worth much more than a decade ago, lowering the fee in absolute satoshis is acceptable while preserving protections.

Developer Gloria Zhao explained the change aims to reduce propagation gaps caused by many sub-1 sat/vB transactions not relaying uniformly, while keeping the default high enough to deter spam. Mempool.Space publicly recommended lower defaults to avoid excessive user overpayment.

Source: Mempool

How will forks and alternative clients respond?

Bitcoin Knots, a fork focused on user control, chose not to inherit Bitcoin Core 29.1 defaults automatically. Knots added GUI options and a ‘corepolicy’ toggle so users can select Bitcoin Core defaults or retain prior settings. That preserves operator choice and slows unilateral network-wide policy shifts.

Frequently Asked Questions

Does the 0.1 sat/vB default force miners to accept lower fees?

No. Miners set mining policies independently. Bitcoin Core 29.1 changes node relay defaults, not miner fee policy. Miners may still prioritize higher-fee transactions, but the relay change increases visibility of low-fee transactions to miners.

Will lowering the default increase spam or DoS risk?

The change was designed to preserve DoS protections by keeping a non-zero relay floor and allowing operators to configure stricter values. Developers balanced lower defaults with operational safeguards to limit abuse.

How can node operators adjust the minimum relay fee?

Operators can modify the minrelaytxfee setting in node configuration or via UI options in forks like Bitcoin Knots. Steps include checking the running version, editing the config, restarting the node, and monitoring mempool behavior.

Key Takeaways

• Major fee cut: Bitcoin Core 29.1 lowers the default minimum relay fee to 0.1 sat/vB, a 90% reduction.
• Adoption dependent: Faster impact requires upgrades across nodes and forks; current 29.1 install base is small.
• Operator control: Node operators and miners retain configuration control; forks may choose different defaults.

Conclusion

The Bitcoin Core 29.1 change to a 0.1 sat/vB default reduces friction for low-fee transactions while keeping basic DoS protections. Network effects will depend on upgrade adoption and miner policies. Monitor node versions and mempool metrics to assess real-world impact and adjust operator settings as needed.

Sources: BitRef node telemetry, GitHub discussion notes, Mempool.Space commentary. Publication date: 2025-09-04. Last updated: 2025-09-15. Author/Organization: COINOTAG.