UST/aUST Exchange rate

Hi, i have tried depositing and withdrawing UST into anchor within short period of time (like less than 5mins) , but i notice there is slight difference of the UST/aUST for both exchange rate? im getting 1.028497 for deposit and 1.024278 for withdrawal. the amount of withdrawal result in lesser than initially i deposited(excluded the tx fees). Is this normal? i saw some mention in other post that aUST value should be increase by 20%/year. but shouldn’t exchange rate be pretty much the same in such short period of time? can someone explain? thanks.

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I’m sceptical of how you calculated the exchange rate. If you review the transactions in Terra Finder, you can see depooist_amount, mint_amount, redeem_amount, and burn_amount; you should use that to determine the exchange rates. The redeem can also have an added fee (not the transaction fee) that may be messing with your numbers.

I just happened to be auditing deposit/redeem mechanism yesterday, and I saw the Market contract’s balance increasing within the 27 millions, and now today it’s in the 28 millions, so I am fairly confident that the rate continued to rise. I suggest you don’t pull out too quickly, or you’ll just lose to tx fees.

I see that made sense now. must be the added fee alters the exchange rate shown in pop up. now that you’ve mentioned, from terra finder in REDEEM is this last section i see: “[3] transfer” there anchor sent to two receipient, so i assume one is the total fees, higher than stated tx fee, (tx fee + added fee) correct?

Btw, how is the added fee determined? how it is calculated?


On all Terra transactions, there are Gas fees and Taxes. From Terra Docs:


Gas is a fee that is added on to each transaction to avoid spamming. Validators set minimum gas prices and reject transactions that have implied gas prices above this threshold. At the end of every block, the compute fees are disbursed to the participating validators pro-rata to stake.


Taxes are used as a stability fee, and the protocol charges a small percentage transaction fee ranging from 0.1% to 1% on every Terra transaction, capped at 1 TerraSDR. This is paid in any Terra currency, and is disbursed pro-rata to stake at the end of every block.

It’s important to consider that Gas fees are always paid by the requester to compute code, while Taxes are always paid by the sender of Terra.

When depositing UST to Anchor, both the Gas (~0.20 UST) and the Taxes (~0.41%, up to 1SDR) are added and shown as a single Transaction Fee, because you, the depositor, are both: calling the smart contract (costs gas), and sending UST (accrues taxes). In contrast, when redeeming your deposit, only the Gas (~0.25 UST) is shown in the Transaction Fee, because, although you are calling the smart contract (and therefore costs you gas), it is now the contract (i.e., ‘Anchor Market’) sending UST back to you, so the contract has to pay the taxes.

That ‘added fee’ listed under transfer simply covers the taxes it has to pay.


Thank you for the details.

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Let’s salute to our fellow calculator guy
very active and dedicated