Encyclopedia How the network works · Entry 100
Lightning routing fees: base fees and proportional fees
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Base unit | fee_base_msat is denominated in millisatoshis. | [1] |
| Proportional unit | fee_proportional_millionths uses parts per million of the forwarded amount. | [1] |
| Direction | Channel update parameters apply to a direction, not one universal fee for both peers. | [1] |
Use consistent units
The advertised calculation is base fee plus amount to forward multiplied by the proportional rate divided by 1,000,000. For an illustrative 1,000-msat base fee, 100 ppm rate and 100,000-satoshi forward, the proportional part is 10 satoshis and the base is 1 satoshi: 11 satoshis in total.
Amounts and rounding must follow the implementation’s integer units. A rate of 100 ppm is 0.01%, not 100%.
A route is built backward from the delivered amount
An earlier hop must forward enough to cover what later hops require. Adding the same percentage once to the final payment can therefore misstate the total cost of a multi-hop route.
The sender evaluates fees alongside available liquidity and timing requirements. A channel advertising a low fee may still be unable to carry the payment.
Do not confuse forwarding with channel funding
Opening and closing channels use Bitcoin transactions whose fees depend on their size and network conditions. Forwarding fees compensate route participation under channel policy.
A wallet or service can also impose its own charges. A useful fee display separates the amount delivered, route fees and any additional service or on-chain costs.
Direct answers
Questions people ask
Are Lightning payments always free?
No. Some routes may charge very little or have zero advertised components, but forwarding, service and channel-management costs depend on the actual payment path and wallet arrangement.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
Lightning channel updates advertise direction-specific forwarding fees, commonly a base fee plus a proportional rate in millionths of the forwarded amount. A multi-hop route can incur multiple forwarding charges. These are separate from the Bitcoin transaction fees involved in opening or closing channels.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimBase unit: fee_base_msat is denominated in millisatoshis.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimProportional unit: fee_proportional_millionths uses parts per million of the forwarded amount.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimDirection: Channel update parameters apply to a direction, not one universal fee for both peers.
Scope: Bitcoin · data through 2026-10-02. Verification: verified · 2026-10-02T18:15:23.891Z.
Link to this claimRevision history
- — Initial Bitcoin encyclopedia entry at this permanent URL.
- — Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- BOLT 7: P2P Node and Channel DiscoveryLightning specification contributors
Direction-specific advertised routing fees and channel update parameters.
Locator: The channel_update Message; HTLC Fees; Example; fee_base_msat; fee_proportional_millionths · Retrieved: 2026-10-02T17:22:20.753ZOpen source - BOLT 2: Peer Protocol for Channel ManagementLightning specification contributors
Channel funding, commitment updates, forwarding and channel closing.
Locator: Channel Establishment; Forwarding HTLCs; Channel Close · Retrieved: 2026-10-02T17:22:20.750ZOpen source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees of Satoshi editorial project. “Lightning routing fees: base fees and proportional fees.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/lightning-routing-fees/