How Rollups Cut Ethereum Fees: The Bundle-and-Post Trick, in Real Dollars
Why does the same token swap cost $5.48 on Ethereum and $0.27 on Arbitrum One? A rollup does the work off Ethereum and posts one compressed receipt back — and hundreds of users split the cost of that single receipt. Those two prices are real, from l2fees.info on November 5, 2026. The gap is not a promotion or a different token. It is the same swap, executed in a different place. This post shows exactly where the $5.21 saving comes from, what your $0.27 actually pays for, and the three cases where a rollup does not save you money. Why Ethereum charges so much in the first place Ethereum is a small pipe, and users bid against each other for space in it. The base layer commits one block roughly every twelve seconds, and each block targets 30 million gas with a hard ceiling of 60 million (ethereum.org). That caps throughput at about 12 to 15 transactions per second. When demand rises, there is no extra room — users simply outbid each other, and fees climb. The peak was not subtle. D...