The Cost of Approvals Over a Year

An approval is a separate transaction from the operation it enables. It has its own gas cost and it is invisible in most people’s mental accounting.

The mechanics

Before a contract can move your tokens, you grant an allowance. That is one transaction.

Then the operation itself is a second transaction.

So a first-time swap on a new protocol costs two transactions, not one. Subsequent swaps cost one, if the allowance remains sufficient.

The gas cost

An approval typically consumes in the region of 45,000 to 55,000 gas, compared with 21,000 for a plain transfer and 120,000 or more for a swap.

So an approval costs roughly two to two and a half times a simple transfer, in gas terms.

The annual arithmetic

For a user who interacts with, say, eight different protocols across a year, using three tokens on each, the approval count is substantial before any actual operations.

On a rollup this is negligible. On mainnet at typical fee levels it is a real number, and at peak fee levels it can exceed the value of small trades entirely.

The revocation cost

Revoking an approval is itself a transaction with a similar gas cost.

Good security practice says revoke unused approvals monthly. That practice has a fee attached, and the fee is why many people do not follow it.

Reducing it

Approve exact amounts only where you will not repeat the operation. An unlimited approval avoids repeated approval costs at the price of standing exposure. This is a genuine trade rather than a rule.

Batch revocations. Several in one session, at a quiet time, rather than one at a time whenever you remember.

Do it on a rollup. Where your activity is on a layer 2, both approvals and revocations cost a fraction of a cent, which removes the tension between security practice and cost entirely.

Weekend mornings. The weekly fee cycle applies to approvals as much as to anything else, and revocations are never urgent.

The security cost of optimising

The cheapest approach is to approve unlimited once and never revoke. That minimises fees and maximises standing exposure.

The safest approach is exact approvals revoked after each use, which maximises fees.

The reasonable middle, for mainnet activity, is unlimited approvals only on long-established protocols you use repeatedly, exact approvals elsewhere, and a batched revocation session quarterly rather than monthly.

For anyone whose on-chain activity is occasional rather than continuous, moving that activity to a rollup resolves the trade-off, because the cost that forced the compromise disappears.

For funds that are not being used in contracts at all, there are no approvals and no associated fees, which is the underrated advantage of keeping the working balance at an exchange with a published withdrawal schedule and the long-term portion in a wallet that never connects.