# Bitcoin L2 and Sidechain BTC Locked: Rootstock, Stacks, Liquid, Mezo

> Bitcoin L2 TVL measured as BTC locked in each peg on Bitcoin: Rootstock's PowPeg, Stacks sBTC, Liquid, Mezo and others, with custody models and peg flows.

Markdown copy of https://voltfincrypto.com/apps/bitcoin-l2-btc-locked

**Question:** How much BTC is locked in Bitcoin L2s and sidechains, and who controls it?

- Kind: Dashboard in Voltfin Vantage
- Topic: [Bitcoin](https://voltfincrypto.com/topics/bitcoin)
- Chains: Bitcoin, Rootstock, Stacks, Mezo
- Status: Planned. The data is not published yet, so this page states no figure; each figure will open its receipt when it is.

This dashboard measures Bitcoin L2s and sidechains by the bitcoin that has actually left the base chain for them: the BTC held in each one's peg or bridge addresses, read from Bitcoin itself. It covers Rootstock's PowPeg, the signers behind Stacks' sBTC, Liquid's federation, Mezo's bridges and the other pegs that publish their addresses, and sets each beside the BTC token supply on its own chain.

Totals that add up everything deployed on these chains mix in wrapped tokens bridged from Ethereum and the chains' own tokens, so they say little about how much bitcoin each peg holds. Here each peg's BTC is counted once, from its addresses on Bitcoin, and wrapped bitcoin bridged from other chains is left out because its BTC sits with the wrapper's custodian.

Pegs also differ in who can move the coins: a federation of known members, a threshold of elected signers or a bridge with on-chain proofs. The custody model of each peg sits beside its balance, because the size of a peg says nothing about how safe it is.

## Blueprint

### All pegs

BTC locked across every tracked peg and how it is held.

- **BTC locked in pegs** (BTC): Bitcoin held in the published peg and bridge addresses of every tracked Bitcoin L2 and sidechain at the latest Bitcoin block.
- **Largest peg's share** (%): The share of locked BTC held by the single largest peg.
- **Pegs tracked** (count): Bitcoin L2s and sidechains whose peg addresses are published and read here.
- **Change, 30 days** (BTC): Net BTC added to or withdrawn from all tracked pegs over the last 30 days.
- **BTC locked by peg** (BTC): BTC in each peg by day: Rootstock's PowPeg, Stacks' sBTC signers, Liquid's federation, Mezo and the others.
- **Locked BTC by custody model**: Locked BTC grouped by who can move it: federations, elected signer sets, proof-based bridges and custodians.

### Peg by peg

Each peg's BTC beside the supply on its own chain.

- **BTC in Rootstock's PowPeg** (BTC): BTC in the PowPeg federation's addresses on Bitcoin at the latest block.
- **BTC behind sBTC** (BTC): BTC in the sBTC signers' address on Bitcoin at the latest block.
- **Locked BTC against chain supply** (BTC): For each peg, the BTC locked on Bitcoin beside the supply of its token on its own chain: RBTC in circulation, sBTC, L-BTC and the others.
- **Every peg**: Each peg with its chain, custody model, signer threshold, BTC locked, supply on its chain and peg flows over 30 days.

Filters: Period (Last 30, 90 or 365 days).

## How it will be measured

- Locked BTC is the balance of each peg's published addresses in the UTXO set at the latest Bitcoin block; when a federation rotates its address, old and new are both counted until the old one is emptied.
- Peg addresses come from each project's documentation or on-chain registry, such as Rootstock's bridge contract, and are recorded with their source.
- The supply on each chain is read there: RBTC outside Rootstock's bridge contract, sBTC's token supply on Stacks and L-BTC issued on Liquid.
- Peg-ins and peg-outs are Bitcoin transactions that pay into or spend from a peg's addresses.

## Data it needs

- `bitcoin_supply_daily` (to build): Bitcoin issued, supply by coin age band and by output script type (including coins whose public keys are already exposed), supply last moved long ago, and cost-basis measures.
- `address_labels` (to build): Labels for known addresses: exchanges, bridges, protocols, funds, treasuries, sanctioned addresses and known attackers.
- `token_supply_daily` (to build): Total supply of each registry token on each chain at day end: wrapped BTC, liquid staking tokens, tokenized assets and other tracked tokens.
- Source: Balances of each peg's published Bitcoin addresses in the UTXO set at day-end blocks
- Source: Rootstock's bridge contract: the current federation address and the RBTC it holds
- Source: sBTC token supply on Stacks and the sBTC signers' deposit address
- Source: Liquid federation peg addresses and the L-BTC issued on Liquid, recorded with their source
- Source: Mezo's bridge contracts and the BTC supply on Mezo
- Source: Bitcoin transactions paying into or spending from each peg's addresses

## Questions

### How much BTC is locked in Bitcoin L2s?

The dashboard adds up the bitcoin held in the published peg and bridge addresses of each tracked Bitcoin L2 and sidechain, read from Bitcoin itself. That is the bitcoin that has actually left the base chain for them, not the value of everything deployed on them.

### What is the difference between a Bitcoin sidechain and a Bitcoin L2?

A sidechain such as Rootstock or Liquid runs its own consensus and holds deposited BTC with a federation of signers. Projects called layer 2s range from systems that post proofs or data elsewhere to chains secured by signer sets; few yet let users withdraw without the signers' cooperation. The custody model column says which applies to each peg.

### How does Rootstock's PowPeg work?

BTC sent to the PowPeg's federation address on Bitcoin is released as RBTC on Rootstock by its bridge contract, and RBTC sent back to that contract releases BTC on Bitcoin. Peg-outs need a threshold of the federation members' signatures, and their keys are held in hardware security modules.

### How is sBTC backed?

sBTC is minted on Stacks when BTC is deposited to an address controlled by a set of sBTC signers, who must reach a threshold to approve withdrawals. The dashboard compares sBTC supply with the BTC in that address each day.

### Why are wrapped tokens on Bitcoin L2s left out?

Wrapped bitcoin bridged from Ethereum, such as WBTC on a Bitcoin L2, is backed by BTC held by the wrapper's custodian, not by the L2's peg. Counting it here would count the same bitcoin twice, so it appears in the wrapped bitcoin dashboard instead.

## Glossary

- **Peg-in and peg-out**: Moving BTC into a sidechain or L2 by sending it to the peg's address, and back out by asking the peg to release it on Bitcoin.
- **Federation**: A fixed group of known members whose signatures, up to a threshold, are needed to move a peg's BTC.
- **Threshold signature**: A signature that needs a set number of a group's members to agree before coins can move.
- **Custody model**: Who can move a peg's BTC and under what rules: a federation, elected signers, a proof-based bridge or a custodian.

## Related apps

- [Wrapped Bitcoin Supply by Chain and Issuer](https://voltfincrypto.com/apps/wrapped-bitcoin-supply-by-chain)
- [Babylon Bitcoin Staking Tracker: BTC Staked and Finality Providers](https://voltfincrypto.com/apps/babylon-bitcoin-staking-tracker)
- [Bridged Token Backing: Locked vs Minted Supply](https://voltfincrypto.com/apps/bridged-token-backing)
- [Who Owns the Most Bitcoin: Holder League Table](https://voltfincrypto.com/apps/who-owns-the-most-bitcoin)
- [Bitcoin Liquid Staking Tokens Compared: LBTC, xSolvBTC and More](https://voltfincrypto.com/apps/bitcoin-liquid-staking-tokens)
- [Bitcoin Halving Countdown and Block Reward](https://voltfincrypto.com/apps/bitcoin-halving-countdown)

Build it in Voltfin Studio: https://app.voltfincrypto.com/signup?next=%2F