1inch fees are network gas costs and Fusion quote trade-offs

1inch fees are the combined cost of network gas, the fees charged by liquidity pools along a route, and any resolver or integration charge already reflected in the quoted output. In Classic mode, your wallet pays gas. In EVM Fusion token swaps, resolvers fund settlement, so their gas and margin influence how many destination tokens the auction delivers.

The useful comparison is net received value: destination tokens after explicit charges and wallet-paid gas. Price impact and slippage affect that value, yet they aren’t protocol fees and need separate labels, as covered in 1inch overview.

Key takeaway: A first ERC-20 Classic swap requires two on-chain transactions when the router lacks an existing allowance.

From quote to settlement on 1inch

A 1inch swap quote is a transaction plan that turns a token pair, amount, and network choice into an executable route. Start by selecting the source and destination assets on one chain, then enter the amount. The interface returns expected output, route details, and an execution mode before any signature.

Next, inspect whether the source token already has a sufficient allowance. Without an allowance, a Classic trade of an ERC-20 token takes 2 on-chain transactions: 1 approval and 1 swap. A sufficient existing allowance reduces the sequence to 1 swap transaction. In Classic mode, the wallet broadcasts the router call and pays the network. In EVM Fusion, the wallet signs EIP-712 order data off-chain, and a resolver broadcasts the fill; a supported permit can replace a standalone approval. Finally, compare the minimum received amount with the separate gas estimate. The quote applies only to its stated route and execution terms, as broken down in 1inch rewards.

Classic, Fusion, Fusion+, and direct DEX quotes

Execution mode is the cost framework that decides who submits settlement, how gas reaches the chain, and which assets can move. Classic and direct Uniswap swaps expose wallet-paid gas; 1inch Fusion, Fusion+, and CoW Swap place execution economics inside an intent quote.

Network scope matters before fee comparison. Ethereum is chain ID 1, Base is 8453, Arbitrum One is 42161, Polygon PoS is 137, and Solana is 501 in 1inch’s swap APIs. Classic covers supported EVM chains, while Fusion adds intent execution and Fusion+ connects eligible networks. A same-chain quote shouldn’t be compared with a cross-chain quote because Fusion+ includes settlement on 2 chains and atomic escrow mechanics. After matching scope, rank the final token output, subtract only gas that your wallet pays, and keep the quote amount and timestamp together.

Network gas in Classic mode

Classic-mode gas is a blockchain execution charge that the connected wallet pays when it broadcasts the 1inch router transaction. The amount equals gas used multiplied by the effective gas price, so both route complexity and block-space demand matter.

A plain ETH transfer uses 21 000 gas, while a contract-based swap consumes more because it executes token and routing logic. Ethereum quotes gas prices in gwei; 1 gwei equals 10^9 wei, and 1 ETH equals 10^18 wei. Under EIP-1559, the effective price combines a burned base fee and a priority fee paid to the validator. The base fee adjusts by at most 12.5% from one block to the next, and the block gas limit has a 2× elasticity factor around its target. A larger gas limit isn’t the final charge: unused gas returns, while consumed gas settles at the effective price.

Base, Optimism, and Arbitrum One add rollup execution and data-publication components, so a multi-hop route still carries a measurable network cost.

When does a gasless Fusion quote cost less?

A Fusion quote is an intent-based auction offer that costs less when its delivered output beats Classic output after Classic gas. For an EVM token order with allowance or permit in place, the resolver pays settlement gas, leaving 0 direct execution-gas debit in the user’s wallet. Gasless describes the payer, not zero economic cost. Fusion+ extends that abstraction across source and destination chains.

The signed EIP-712 order defines a desired rate, a minimum return, and an expiry. Resolvers watch a Dutch auction whose exchange rate moves toward that minimum until a fill becomes profitable. Their calculation includes gas, available liquidity, inventory, and margin; those costs appear through the offered output rather than a separate native-token charge. The technical API exposes 4 preset labels - fast, medium, slow, and custom - which change auction parameters rather than establishing a universal fee. Batch filling and matched orders reduce a resolver’s per-order execution cost, while competition determines how much of that saving reaches the quote.

Pool fees inside an aggregated route

Source-pool fees are trading charges that 1inch inherits from the liquidity venues selected by Pathfinder for a particular route. Each pool deducts its own fee as the trade crosses it, and the displayed destination amount already reflects that route.

Uniswap v3 pools use fee tiers including 0.01%, 0.05%, 0.30%, and 1.00%, while Uniswap v2 charges a flat 0.30%. Uniswap v4 permits pool fees from 0% to 100% in 0.0001% increments and supports dynamic fee logic through hooks. Liquidity providers receive pool fees under each protocol’s distribution rules, less any enabled protocol share. Curve, Balancer, and SushiSwap use their own pool configurations, so identical token pairs needn’t carry identical charges. When Pathfinder splits an order across several pools, each leg applies its venue’s rules, while the aggregate quote reports one expected output.

Pool fees compound through the path; subtracting them again from quoted output would double-count the same charge.

Approvals and permits as separate costs

Token approval is an ERC-20 allowance transaction that adds a network charge before the swap itself reaches the router. That gas goes to the chain’s fee mechanism, while the approval only authorizes a spender and transfers no trade output.

Without a sufficient allowance, the standard EIP-20 flow uses 2 transactions: approve, then swap. EIP-2612 adds 3 functions - permit, nonces, and DOMAIN_SEPARATOR - and lets an EIP-712 signature set an allowance; a successful permit increments the owner’s nonce by 1. 1inch’s intent API also supports Permit2-formatted approval data when the selected token and route support it. An existing allowance or a valid permit removes the standalone approval broadcast, yet the swap or resolver fill still follows its own execution path. Approval cost belongs in the first-trade comparison, not every later quote.

USDC uses 6 decimals and WETH uses 18, so raw quote fields need normalization before fee arithmetic makes sense.

Converting every charge into net output

Net output is a common-denominator calculation that converts explicit charges and wallet-paid gas into the destination token before quotes are ranked. A useful 1inch fees comparison starts with displayed output because it already incorporates the liquidity route and its pool fees. Don’t subtract price impact as a fee; it already shapes output, while the slippage limit governs execution tolerance.

Take a hypothetical comparison where Classic returns 1 000 output units and its gas estimate converts to 6 output units; Classic nets 994. Fusion returns 992 units with 0 wallet-paid execution gas, so its net remains 992. Classic leads by 2 units, despite Fusion’s gasless label. Keep partner charges in the same arithmetic. Classic Swap API v6.1 accepts a partner-fee setting from 0% through 3%. One basis point equals 0.01%, so 25 basis points equal 0.25%; on a 10 000-unit fee base, that charge is 25 units. The integration’s configured receiver collects the fee, so its visible setting governs the comparison.

Reading the final confirmation as a cost boundary

The confirmation screen is a binding cost boundary that brings quoted output, gas estimate, approval state, and execution mode together. In Classic, the wallet shows a maximum network spend; the receipt later records gas actually consumed.

Read the minimum received amount as a price-protection threshold, not another deduction. For Fusion, examine the auction’s expected output, minimum return, and expiry alongside any displayed resolver or integrator charge. For Classic, keep the approval transaction separate from the swap estimate if allowance is missing. An API-based route may also create swap surplus when execution beats the quoted amount; the applicable route terms determine whether 1inch retains that improvement. Surplus isn’t an added wallet debit, but it changes who receives favorable execution beyond the committed quote.

The decisive comparison uses the same chain, token amount, execution window, and destination asset, then ranks spendable output after wallet-paid gas.