# Gas Estimates Versus Gas Paid: A Reconciliation

> The estimate shown before a transaction and the amount actually deducted are different numbers. How different, and why.

- Source: https://swapcostnotes.com/gas-estimates-versus-gas-paid/
- Published: 2026-10-13
- Author: Lena Virtanen
- Publication: Swap Cost Notes — What the conversion actually took
- Topic: swap
- Tags: swap, fees, networks

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Wallets show an estimated network fee before a transaction and deduct an actual one after. The two rarely match exactly.

## Why an estimate is an estimate

The fee depends on how much work the transaction turns out to require and on the price of that work at the moment it is included. Neither is known in advance.

The wallet guesses both, usually conservatively, which is why the actual charge is frequently lower than the estimate.

## The two components

A quantity of work and a price per unit of work. A simple transfer uses a predictable quantity; a contract interaction does not.

Price per unit moves with congestion, sometimes within a single block.

## What the reconciliation shows

For simple transfers, estimates and actuals are usually close, with the actual slightly below. For contract interactions, the spread is wider in both directions.

The cases where actual exceeds estimate are the ones worth examining: they usually mean the transaction did more than expected, which is occasionally a sign that it did something unintended.

## The failed transaction case

A transaction that reverts still consumes work and still pays. You are charged for the attempt and receive nothing.

This is the single most surprising line in any reconciliation, and it is correct behaviour rather than an error.

## What to record

Estimated fee, actual fee, whether it succeeded, and the congestion level at the time. Four fields, and after twenty entries you know your own wallet's bias.

A wallet that consistently over-estimates by a large margin is costing you nothing directly but is distorting every decision you make about whether a transfer is worth making.

## Why exchange withdrawals differ

A venue charges its own flat withdrawal fee rather than passing through the network cost. The reconciliation there is between the venue's fee and the actual network cost, and the difference is the venue's margin.

That margin is usually positive and sometimes large. [Exchanges that price the network fee separately from the spread](https://collectnexchange.cy/services/swap) let you see it; those quoting a blended number do not.

## The practical use

Knowing your typical actual cost per transfer, per network, lets you calculate the minimum amount worth moving. [A venue with a published conversion schedule](https://collectnexchange.cy/services/crypto-exchange) publishes its side of that, and [Collect & Exchange](https://collectnexchange.cy/) lists it per network, which is the only form in which the number is useful.

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This article explains how something works. It is not financial advice.
Canonical HTML version: https://swapcostnotes.com/gas-estimates-versus-gas-paid/