Bridge slippage vs quote: what actually settles versus what was quoted
The gap between what a bridge quotes and what actually settles on-chain, in USD, on real executed USDC transfers, plus our own gas, at $3 and $30, measured from EU-West.
TL;DR. As of , Mobula posts the lowest slippage vs quote at -$0.00378 (7d) across 4 ranked providers. Source: OpenChainBench, https://openchainbench.com/benchmarks/bridge-realized-cost.
Every bridge quotes a cost. This benchmark measures whether that quote survives contact with the chain. We broadcast and settle real USDC transfers through Mobula, Relay, LI.FI and Near Intents on a self-conserving triangle, then record the realized fee against the fee the quote promised. The headline is that gap, in dollars: a bridge whose settlement matches its quote sits near zero, a bridge that fills below quote reads positive, and a bridge that beats its quote reads negative. Alongside it we surface the gas the user actually pays to execute (approve plus deposit) and the value that actually landed on the destination. Quotes are a promise; this is the settlement.
Methodology
For every executed transfer we record the realized fee (amount sent minus amount received on-chain) and subtract the quote-projected fee, giving the execution slippage versus the quote in USD. The headline is the 7-day median of that gap (one execution per corridor per day, $3 and $30 pooled). Companion panels report our own on-chain gas (approve plus deposit, measured as the source-chain native balance delta) and the realized output that landed on the destination. Sampled at $3 and $30 from EU-West on the same conserving USDC triangle as the execution-latency benchmark, so cost and latency are measured on the identical transactions.
Results: 4 providers ranked by Slippage vs quote (7d)
| № | Providers | p50 | Realized fee (bps of ticket) | All-in gas we paid | Success |
|---|---|---|---|---|---|
| 1 | Mobula | -$0.00378 | 0.18% | $0.00709 | 100.00% |
| 2 | LI.FI | -$0.0000127 | 1.04% | $0.00769 | 100.00% |
| 3 | Relay | $0.0000037 | 0.79% | $0.00326 | 100.00% |
| 4 | Near Intents | $0.00875 | 0.27% | $0.0615 | 100.00% |
Frequently asked
How is this different from the bridge fee benchmark?
The fee benchmark measures the cost a quote advertises. This one measures the cost that actually settled on-chain and subtracts what the quote promised, so it captures the gap a user only discovers after they commit. A bridge can quote cheap and settle worse, and only an execution benchmark surfaces that.
Why can the number be negative?
Because a bridge can settle better than it quoted. Slippage vs quote is realized fee minus quoted fee, both defined against the ticket (ticket minus landed, ticket minus quoted output), so a solver that fills above the quoted output makes the figure negative. Near zero means the quote was honest; positive means the execution cost more than promised.
Does this include the gas I pay?
The headline is the bridge's own quote-to-settlement gap. Our own execution gas (approve plus deposit) is reported separately in the all-in gas panel, measured as the real native-token balance delta, because it is a cost the user bears on top of the bridge fee.
Where does this run from?
EU-West, on the same executed transactions as the bridge execution latency benchmark. The execution node holds a single wallet, so cost and latency are always measured on the identical transfer.
Source code github.com/ChainBench/OpenChainBench/tree/main/harnesses/bridge-monitor