<p>The shorter the blocktime the more time is lost by the relaying of blocks in relation to the average blocktime. A very short block interval therefore makes SPV mining (i.e. mining empty blocks without transactions) more attractive, and increases the advantage of large pools, because they can start mining on top of their own block the quickest.</p>
<p>Additionally, it increases the number of headers that need to be verified and stored by any client, even smartphone wallets.</p>
<hr />
<p><sub>Also see <a href="https://bitcoin.stackexchange.com/q/113505/5406">How would faster blocks cause mining centralization?</a>
for a more comprehensive explanation how the block interval influences mining incentives.</sub></p>

CC BY-SA 4.0
2022-08-19T13:45:41.480Z
Related: https://bitcoin.stackexchange.com/questions/113505/how-would-faster-blocks-cause-mining-centralization/113506#113506
Antoine Poinsot
CC BY-SA 4.0
2022-08-19T14:55:34.523Z
@AntoinePoinsot: Thanks, I added a link
Murch
CC BY-SA 4.0
2015-07-13T21:19:33.430Z
2022-08-19T14:55:26.123Z
2022-08-19T14:55:26.123Z
Murch
<p>I've heard a couple of times "a shorter blocktime is unsafe," (first about Litecoin and now Ethereum) but never understood why. Is it the higher probability of a fork? Why do some people consider a shorter blocktime less safe?</p>

<litecoin><alternatives><altcoin><ethereum><block-interval>
Why is a short blocktime considered to be unsafe?
Steve Ellis
# Why is a short blocktime considered to be unsafe?

(Asked by: username_0 on 2015-07-13)

I've heard a couple of times "a shorter blocktime is unsafe," (first about Litecoin and now Ethereum) but never understood why. Is it the higher probability of a fork? Why do some people consider a shorter blocktime less safe?

**Tags:** litecoin, alternatives, altcoin, ethereum, block-interval


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## 1 answers

### Answer by username_1 on 2015-07-13. Score: 6 | Accepted answer

The shorter the blocktime the more time is lost by the relaying of blocks in relation to the average blocktime. A very short block interval therefore makes SPV mining (i.e. mining empty blocks without transactions) more attractive, and increases the advantage of large pools, because they can start mining on top of their own block the quickest.

Additionally, it increases the number of headers that need to be verified and stored by any client, even smartphone wallets.

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Also see [How would faster blocks cause mining centralization?](https://bitcoin.stackexchange.com/q/113505/5406)
for a more comprehensive explanation how the block interval influences mining incentives.

> **Comments:**
> **username_2**: Related: https://bitcoin.stackexchange.com/questions/113505/how-would-faster-blocks-cause-mining-centralization/113506#113506  
> **username_1**: @username_2: Thanks, I added a link  

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