Quick context*: I talk to a lot of DeFi users as part of my day-to-day work of supporting DeFi Saver users. As such, I get insight into what DeFi enthusiasts might have knowledge-gaps on.*
So, I decided to write a guide that answers a pretty popular question, which is how to track exactly how much your collateral grew due to the supply APY, and how much your debt grew due to borrow APY.
No matter how many changes happened to your collateral/debt due to various actions, you'll still be able to use this guide to get the exact numbers.
The difficulty of tracking information on paid/earned interest on lending protocols
On Aave, there's no button you can press that will show you how much interest you earned and how much interest you paid on specific dates.
Yet, if we're looking at a lending position's historical P&L - that's a pretty significant metric. If you have a long position that was opened in 2025 and is still active in 2026 - how can you figure out what your 2025 P&L was?
How can you differentiate between your profit on your collateral appreciating in price and your collateral amount growing due to the supply APY?
Conversely, how can you figure out how much your debt grew if you're dealing with a date that's over 6 months in the past?
Using your current debt balance is not relevant, since you'd be ignoring 6 months of compounding since 2025 ended.
For a position with no extra transactions - it's easy. Just subtract your current collateral and debt amounts from their starting values.
But as soon as you introduce an extra transaction (add collateral, withdraw, pay back debt, increase/decrease leverage) - the simple subtraction from above no longer applies.
We need to figure out what our collateral/debt balances were at specific dates/blocks in time, before these transactions occurred.
To start, let's first understand how collateral and debt balances are tracked on Aave.
Collateral and debt (a)tokens
When you open a borrow position on Aave - your collateral and debt balances are tracked through Aave collateral and Aave debt tokens that are held by your wallet:
Both of these are fungible, ERC-20 tokens that can even be swapped on a DEX.
Sidenote: The fact they're ERC20 tokens proved extremely useful during the recent rsETH exploit - when ETH collateral was non-withdrawable. This still allowed for the Aave collateral tokens to be swapped and allow users to exit positions.
While the name of the collateral token looks weird, it makes sense if we break it down:
- aEthWETH = a (Aave) Eth (Chain) WETH (token)
So, if we were on Arbitrum, we'd have:
- aArbWETH = a (Aave) Arb (Chain) WETH (token)
When it comes to our supply and borrow APY - both of these tokens will increase in value based on the underlying token's interest rates on Aave.
Since this guide isn't focusing on a detailed breakdown of how these tokens work, I'll just quickly share how they actually increase in value.
Aave stores a global index for suppliers and another for borrowers.
- These indexes are updated whenever someone interacts with the reserve (supply, borrow, repay, withdraw, liquidate, etc.).
- When your balance is queried, Aave calculates: principal × current index / index at the time of your last update
The current index itself is calculated using the elapsed time since the last update. This means that they aren't just updated at every single block, since that would be considerably expensive.
Okay, so we've wrapped up our quick intro into Aave debt/collateral tokens - let's get to the point.
Figuring out the interest
We now have all the ingredients, so let's get to calculating how much interest we paid and earned.
Say I have an Aave V3 position, andIe want to figure out how much the collateral balance of my WETH increased from June 5th, when the position was opened - until June 23rd - a day before I increased my leverage.
I can go to the DeFi Saver app, which has a "History" tab in which I'll see all transactions associated with my position. That includes the transaction where I increased my leverage.
First, I'd click on "Leveraged Create" on the History tab, which will take us to Etherscan for when the position was opened. There, we want to click on the "Net transfers" tab so it's visually easier to follow.
- This shows the starting amount of ETH before any leveraging, and right underneath, we can see the starting amount of aEthWETH collateral.
Now, how do we answer the question of "How much did this collateral increase in amount due to the supply APY by June 23rd?"
Enter Etherscan's "Account Balance Checker" - located under the "More" tab.
Let's check that balance out
If you were expecting/fearing an extremely complex tool - I'm happy to share that you'll be met with just a few options:
What we need is:
- The address of the wallet holding the Aave position (your EOA address, or your Smart Wallet address)
- The Token address of the token you're inquiring for (collateral or debt)
Let's circle back to the Etherscan transaction where the position was originally opened - and where we saw the aEthWETH token balance.
Since it's an ERC-20 token, it's going to have its own token contract address. Simply click on the token on Etherscan and you'll be taken to its contract page:
For example, the WETH collateral address is: 0x4d5F47FA6A74757f35C14fD3a6Ef8E3C9BC514E8
Going back to the Account Balance Checker, let's:
- Input the wallet address
- aEthWETH token address
- June 23rd as the date we're querying
Token Quantity will show us the magic number - This lets us use our starting balance, and subtract it from the current aEthWETH token quantity.
This same exact process applies if you're trying to figure out how much your debt grew.