<p>The blocks/ subdirectory in the Bitcoin Core datadir contains more than just blocks. For every processed block (which are stored in blk?????.dat files), it also stores &quot;undo data&quot; (stored in rev?????.dat files). These files contain the information necessary to quickly revert the effect of a block if it is ever discovered that it is not part of the best chain anymore.</p>
<p>I suspect that if you just count the blk?????.dat files, you'll end up with a size much closer to the expected blockchain size.</p>

CC BY-SA 4.0
2021-08-22T19:41:33.467Z
The rev* files contain roughly 49 GB. That's it! (So the "undo data" adds about 14% to the blocks storage requirement.)
brec
CC BY-SA 4.0
2021-08-22T19:16:40.763Z
2021-08-22T19:16:40.763Z
Pieter Wuille
<p>On a Mac which Bitcoin Core updated a few minutes ago, the the Blocks folder contains 409.55 GB and the Chainstate folder contains 4.57 GB. But...</p>
<p><a href="https://www.blockchain.com/charts/blocks-size" rel="nofollow noreferrer">https://www.blockchain.com/charts/blocks-size</a> shows, as of yesterday, about 360 GB excluding database indexes.</p>
<p><a href="https://ycharts.com/indicators/bitcoin_blockchain_size" rel="nofollow noreferrer">https://ycharts.com/indicators/bitcoin_blockchain_size</a> shows, as of today, about 360 GB.</p>
<p><a href="https://www.statista.com/statistics/647523/worldwide-bitcoin-blockchain-size/" rel="nofollow noreferrer">https://www.statista.com/statistics/647523/worldwide-bitcoin-blockchain-size/</a> shows, as of Aug. 15 (a week ago) about 351 GB.</p>
<p>The Mac's Blocks folder contains 5,454 files; the Chainstate folder, 2,226 files. The size difference is about 414 - 360 = 54 GB, or about 7.24 MB difference per file (using 1,024 MB per GB). Does that amount of file overhead seem reasonable and thus possibly the explanation?</p>

CC BY-SA 4.0
2021-08-22T19:15:15.340Z
Gigabytes can be base 8 or base 10 depending who is displaying them.
Claris
<blockchain>
Why discrepancies in blockchain GB size between Mac and web sources?
brec
# Why discrepancies in blockchain GB size between Mac and web sources?

(Asked by: username_0 on 2021-08-22)

On a Mac which Bitcoin Core updated a few minutes ago, the the Blocks folder contains 409.55 GB and the Chainstate folder contains 4.57 GB. But...

<https://www.blockchain.com/charts/blocks-size> shows, as of yesterday, about 360 GB excluding database indexes.

<https://ycharts.com/indicators/bitcoin_blockchain_size> shows, as of today, about 360 GB.

<https://www.statista.com/statistics/647523/worldwide-bitcoin-blockchain-size/> shows, as of Aug. 15 (a week ago) about 351 GB.

The Mac's Blocks folder contains 5,454 files; the Chainstate folder, 2,226 files. The size difference is about 414 - 360 = 54 GB, or about 7.24 MB difference per file (using 1,024 MB per GB). Does that amount of file overhead seem reasonable and thus possibly the explanation?

**Tags:** blockchain

> **Comments:**
> **username_1**: Gigabytes can be base 8 or base 10 depending who is displaying them.  

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## 1 answers

### Answer by username_2 on 2021-08-22. Score: 4 | Accepted answer

The blocks/ subdirectory in the Bitcoin Core datadir contains more than just blocks. For every processed block (which are stored in blk?????.dat files), it also stores "undo data" (stored in rev?????.dat files). These files contain the information necessary to quickly revert the effect of a block if it is ever discovered that it is not part of the best chain anymore.

I suspect that if you just count the blk?????.dat files, you'll end up with a size much closer to the expected blockchain size.

> **Comments:**
> **username_0**: The rev* files contain roughly 49 GB. That's it! (So the "undo data" adds about 14% to the blocks storage requirement.)  

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