L2 Gas Tracker
2026-09-12 · By L2 Gas Tracker Research

How Much ETH Do You Need for Gas on Base and Arbitrum?

Wallet holding small amount of ETH for gas on Base and Arbitrum layer 2 networks

The question everyone arrives at eventually

"I bridged some USDC over to Base. Why won't it let me swap?"

Because gas on Base and Arbitrum is paid in ETH, not USDC, not any stablecoin, not the token you're trying to trade. Always ETH. You need a small dusting of the native asset sitting on the network before anything else works. The good news: the amount you need is almost offensively small. This is the question I answer in friends' group chats about twice a week, so here's the actual math.

The short answer

Keep $5 to $10 worth of ETH on whichever L2 you're using. At ETH around $2,500, that's roughly 0.002 to 0.004 ETH. That sounds like nothing, and on L2 it actually is nothing — because each transaction burns a tiny fraction of a cent.

Five dollars on Base typically covers 30 to 50 real transactions: swaps, mints, approvals, the lot. On Arbitrum it's slightly more like 20 to 40, because fees there are marginally higher and move with mainnet congestion (more on that below). Either way, $5 is a month of normal usage for most people. You don't need to move meaningful amounts of ETH across — just enough that the wallet never runs dry.

What each action actually burns

Here's roughly how much gas a single action eats, on a normal day:

Add those up across a month of casual use and you'll see why five dollars stretches. The numbers drift up 3 to 10x during mainnet congestion, which is worth knowing — the main tracker shows the live slow/fast prices before you commit to anything.

The approval trap new users fall into

When you swap a token for the first time, you get prompted twice: first an "Approve" transaction, then the actual swap. Both cost gas. That approve is you giving the permission for the exchange contract to touch that specific token — it only happens once per token, but it does cost you a bit of ETH.

So if you're arriving with a stack of USDC and plan to trade several different tokens, budget for a handful of approvals in your first session. It's not expensive — a few cents each on L2, versus $5 to $20 on Ethereum mainnet — but it's why people who moved over "just enough ETH for one swap" get stuck mid-way. I wrote the whole approval fee explainer if you want the mechanism.

The one time you need real ETH: bridging

Everything on Base or Arbitrum is cheap. Getting money onto them is not, because that bridging transaction runs on Ethereum mainnet and you pay full mainnet gas — $2 to $15 depending on the day. This is the single biggest fee you'll ever pay in the L2 workflow, so two rules:

And when you do bridge, bring across the ETH for gas in the same trip. I've watched people bridge USDC only, then have to do a second bridge just for gas. Bridge a chunk of ETH plus your stablecoins together. The cost breakdown and timing advice are in the cheap-window analysis I put together.

So what's the actual number to move?

Concrete recipe that works for me: when I'm setting up a fresh L2 wallet, I make sure about $10 of ETH is sitting on it, plus whatever stablecoins I actually came to trade or invest. That gas buffer lasts me a few months without ever once seeing the "insufficient funds for gas" error. If you only plan to do a transaction or two, $5 is fine. Below $2 and you're likely to hit a dry wallet mid-session.

One last thing: a failed transaction still costs gas. If you approve something you don't hold, or a swap reverts on slippage, you lose the fee and get nothing. So the cheapest thing on the tracker isn't always the right tier — but for an L2 this cheap, overpaying a tenth of a cent for reliability is a trade I'll make every time. The Base calculator and Arbitrum calculator show the live dollar and local-currency cost before you sign.

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