Unlimited Approval vs Limited Approval: Which Is Safer?

Unlimited approvals grant a smart contract permission to move an effectively uncapped amount of a token from your wallet indefinitely, while limited approvals cap that permission to a specific amount — usually just what a single transaction needs — at the cost of requiring a new approval transaction, and a small additional gas fee, the next time you interact with that contract.

If you're new to how token approvals work at all, our companion piece on what token approvals are covers the underlying mechanics. This article focuses specifically on weighing the two approaches against each other.

How each option actually behaves

An unlimited approval sets the permitted amount to the maximum value the token contract's numeric field supports — in practice, an amount so large it will never be exhausted by ordinary use. Once set, the approved contract can call transferFrom for any amount up to your full token balance, at any time, until you manually revoke the approval or set it to zero.

A limited approval sets the permitted amount to a specific number — commonly whatever the pending transaction requires. Once that amount is used (fully or partially, depending on the transaction), the remaining allowance drops correspondingly, and a new approval transaction is required before the contract can move any more of that token.

The security case for limited approvals

The core risk with any approval is that it remains a standing liability for as long as it's active — if the approved contract is ever compromised, maliciously upgraded (where upgradeable contracts allow it), or was malicious from the outset, an attacker can move up to the approved amount without requiring any further action from you. With a limited approval, the maximum possible loss from that specific approval is capped at the amount you actually approved, rather than your entire token balance. This is a meaningful difference if you're interacting with a newer or less battle-tested protocol, where the odds of an eventual exploit are harder to assess.

The convenience case for unlimited approvals

Unlimited approvals exist for a legitimate reason: gas fees. Every approval transaction costs network fees, and if you interact with the same protocol regularly — say, a DEX you use weekly — a limited approval means paying that fee every single time, which adds up in both cost and friction. An unlimited approval to a protocol you trust and use frequently trades a one-time, larger risk exposure for meaningfully lower ongoing costs and fewer transactions to sign.

Direct comparison

Factor	Unlimited approval	Limited approval
Maximum exposure if contract is compromised	Full token balance	Approved amount only
Gas cost over repeated use	Lower (approve once)	Higher (approve per use, or per refill)
Convenience	Higher — fewer signatures needed	Lower — more frequent approval transactions
Best suited for	Established protocols you use often and trust	New, occasional, or higher-risk protocol interactions
Requires ongoing maintenance	Yes — should be periodically reviewed/revoked	Naturally self-limiting after use

A practical middle ground

Many experienced users apply a simple rule: use limited approvals by default, especially for new, unaudited, or infrequently used protocols, and reserve unlimited approvals for a small number of well-established, actively maintained platforms where the convenience benefit is clearly worth the tradeoff. Under this approach, an unlimited approval isn't inherently reckless — it's a deliberate choice made about a specific, trusted counterparty, not a default applied indiscriminately everywhere.

Whichever approach you take, treat approval review as an ongoing task rather than a one-time setup decision — protocols you trusted at the time of approval can change (through a compromised upgrade key, a hack, or a shift in team behavior) long after you've stopped paying attention. Our guide on how often to revoke approvals and roundup of approval checker tools cover how to build that review into a routine.

Setting approval amounts in practice

Most wallet interfaces default to requesting the unlimited amount, and changing it to a specific number typically requires manually editing the approval amount field before confirming — an extra step many users skip simply because they don't know the option exists. Taking that extra moment, particularly for larger amounts or less familiar protocols, is a low-cost way to materially reduce your worst-case exposure. General DeFi wallet security practices reinforce this same theme: small deliberate frictions at the point of signing prevent much larger losses later.

Bottom line

Neither option is universally correct — unlimited approvals are a reasonable, deliberate tradeoff for protocols you trust and use often, while limited approvals are the safer default for anything newer, less proven, or used only occasionally. The mistake to avoid isn't choosing unlimited approvals; it's granting them by default, without noticing you had a choice, and never revisiting them again.