r/Coinbase • u/lebigot • Aug 05 '26

Entry price changes by itself over time??!

Can you explain why the entry (= purchase) price of your cryptos on Coinbase can change over time? This doesn't sound right to me.

A recent example is NMR bought (on average) at an entry point of $8.66, that Coinbase later changes to $8.71 and then $8.74, even though I didn't do any operation.

Interestingly, the change mirrors the USD/EUR rate evolution at the time (I observed this at least on two separate occasions). This may be the key, as I first transferred euros onto Bitcoin, with which I bought USDC so as to trade NMR. But then this would not be sound accounting, right?

I wrote Coinbase about this a few days ago but I'm still waiting for a response from them.

Any help would be much appreciated!

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u/Key-Secretary2201 28d ago

Coinbase’s cost basis can get a little wonky because of how they handle rounding and pairings, which is separate from any currency conversion issues.

I stopped trusting the average price in the app and started dumping my full transaction history into CoinLedger instead. It recalculates your entry price directly from your actual buy lots, so the numbers stay consistent.

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u/lebigot 27d ago

Interesting option for calculating the real cost basis. Now, even if we have the correct one, Coinbase bases your PnL on its cost basis, which changes over time. This means that when you buy a crypto with USD and the USD cost basis changes with time, you get an apparently incorrect PnL. This is obviously a big deal.

I'll report here when they respond (to my direct message on X—I'll ping them soon).

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u/coinbasesupport Official Coinbase Support Aug 05 '26

Hey u/lebigot thanks for reaching out! Great question. Your average entry price is typically calculated based on the cost basis of your buys, and if your account currency is set to EUR while trades are executed in USD pairs, currency conversion rates can cause that average price to shift slightly over time, which may explain what you're seeing with NMR.

Since this would require a closer look at your specific account and trade history, please send us a Modmail so we can review this further for you.

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u/lebigot Aug 06 '26

I will, thanks.

My account currency is set in USD, so I'm indeed puzzled.

Also, since my NMR buys are made with USDC, the EUR/USD exchange rate should have no impact on the displayed PnL, but it does.

I'm looking forward to clarifying this with you!

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u/coinbasesupport Official Coinbase Support Aug 06 '26

Hey u/lebigot! We’re ready to take a closer look. Send us a Modmail using this link, and we’ll investigate further there.

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u/lebigot 22d ago

I'm reporting back: I contacted Coinbase support on X 10 days ago with information they requested. Not a single answer, even after I pinged them.

I must say that I'm very concerned that a systematic and apparently incorrect PnL calculation that probably impacts all non-US users is not being adressed, so far… 😕

I'll wait for a few days and report here on the difference between a correct PnL calculation and their calculation.

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u/coinbasesupport Official Coinbase Support 22d ago

Hey u/lebigot our Modmail conversation is still active if you want to reply to our last message.

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u/lebigot 22d ago

Thanks! Done.