# Block Header Size and Growth

<figure><img src="/files/lCU9ox53m1nwQKOfYrvM" alt=""><figcaption></figcaption></figure>

*A block header with no transactions would be about 80 bytes. If we suppose blocks are generated every 10 minutes, 80 bytes \* 6 \* 24 \* 365 = 4.2MB per year. With computer systems typically selling with 2GB of RAM as of 2008, and Moore's Law predicting current growth of 1.2GB per year, storage should not be a problem even if the block headers must be kept in memory.*

Satoshi Nakamoto, Bitcoin Whitepaper

The **block header** serves as a concise record of a block's existence, containing essential information such as the previous block's hash, the timestamp, and the Merkle root. A block header without transactions is approximately **80 bytes** in size. Given that blocks are generated roughly every 10 minutes, the annual growth of block headers can be calculated as follows:

* **80 bytes/block** × **6 blocks/hour** × **24 hours/day** × **365 days/year** = **4.2 MB/year**

This **growth rate is manageable**, especially considering that computer systems have historically been equipped with increasing amounts of RAM. As of 2008, systems typically came with **2GB of RAM**, and with Moore's Law predicting an annual growth of **1.2GB**, the storage of block headers remains feasible even as the blockchain expands.


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