# Lightning routing fees: base fees and proportional fees

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.

Evidence: [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md); [BOLT 2: Peer Protocol for Channel Management](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/02-peer-protocol.md)

Canonical: https://degreesofsatoshi.com/encyclopedia/lightning-routing-fees/
Published: 2026-10-02
Substantively modified: 2026-10-02
Independently verified by an automated reviewer: 2026-10-02T18:15:23.891Z
Data current through: 2026-10-02

AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied.

## Key facts

- **Base unit:** fee_base_msat is denominated in millisatoshis. ([BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md))
- **Proportional unit:** fee_proportional_millionths uses parts per million of the forwarded amount. ([BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md))
- **Direction:** Channel update parameters apply to a direction, not one universal fee for both peers. ([BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md))

## 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%.

Evidence: [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md)

## 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.

Evidence: [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md)

## 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.

Evidence: [BOLT 2: Peer Protocol for Channel Management](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/02-peer-protocol.md); [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md)

## Questions

### 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.

Evidence: [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md); [BOLT 2: Peer Protocol for Channel Management](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/02-peer-protocol.md)

## Claims and scope

### lightning-routing-fees-quick-answer

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: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null}

### lightning-routing-fees-fact-base-unit

Base unit: fee_base_msat is denominated in millisatoshis.

Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null}

### lightning-routing-fees-fact-proportional-unit

Proportional unit: fee_proportional_millionths uses parts per million of the forwarded amount.

Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null}

### lightning-routing-fees-fact-direction

Direction: Channel update parameters apply to a direction, not one universal fee for both peers.

Scope: {"collection":"bitcoin","dataAsOf":"2026-10-02","blockHeight":null}

## Sources

- [BOLT 7: P2P Node and Channel Discovery](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/07-routing-gossip.md) — Lightning 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: 2026-10-02T17:22:20.753Z.
- [BOLT 2: Peer Protocol for Channel Management](https://raw.githubusercontent.com/lightning/bolts/1aadb719b4007c4cea0ba6e36b08c4fb53788dee/02-peer-protocol.md) — Lightning specification contributors. Channel funding, commitment updates, forwarding and channel closing. Locator: Channel Establishment; Forwarding HTLCs; Channel Close. Retrieved: 2026-10-02T17:22:20.750Z.

## Revision history

- 2026-10-02: Initial Bitcoin encyclopedia entry at this permanent URL.
- 2026-10-02: Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification.

## Cite this entry

Degrees 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/