# baseFee can actually increase/decrease by more than 12.5?

according to some articles written on the EIP1559 topic, baseFee should only change by maximum 12.5%

However, in reality this is not always the case. Check these examples:

``````block 13096125 baseFee = 117.62 gwei
block 13096126 baseFee = 102.91 gwei

117.62 / 102.91 = 1.14294043 > 1.125

``````

Another example would be:

``````block 13096220 baseFee = 142.03 gwei
block 13096221 baseFee = 124.63 gwei

142.03 / 124.63 = 1.13961326 > 1.125

``````

The question is: what's wrong with these blocks and their `baseFee` values? Are the sources/articles given above not accurate? Or maybe I'm calculating it wrong?

That gas price is not the baseFee, it is baseFee + some implicit average of all the miner tips in that block. baseFee cannot increase/decrease more than 12.5% per block.

EDIT: You calculations are wrong: 142.03 * (1 - 0.125) = 124.27625

So 124.27625 is the lower boundary for the gas after one block that is 0% full, which is still below 124.63

With those calculations you aer basically calculating the growth on the most recent block, not on the previous block.

• well, etherscan claims it's baseFee etherscan.io/block/13096220. And it's also what you get if you do direct RPC calls and parse block header Aug 25, 2021 at 20:45
• `2 + 0.047019578508113883 - 0.042179744920646781`. You are looking at a block with only 5 transactions and hence where the sum of the miner tips is almost 0 for the block, so the real baseFee and the fee on that column will be almost identical (and in that column is rounded to 2 decimals only). Check for a block with many more transactions and you will see the difference. Aug 25, 2021 at 20:48
• I don't understand your point. The fact is the difference between `baseFee` values of two nearby blocks is more than 12.5%. I'm trying to understand why it's so. `baseFee` is different thing to priority fee, I'm not talking about priority fees here Aug 25, 2021 at 20:54
• I was wrong, I've rechecked the problem and edited my answer. Aug 25, 2021 at 21:06
• nice one, that does make sense 👍 Aug 25, 2021 at 21:20