<p>No, BIP158 basic filters have a fixed false positive rate of exactly 1/784931, regardless of how many elements they contain.</p>

CC BY-SA 4.0
2023-02-05T18:32:31.810Z
2023-02-05T18:32:31.810Z
Pieter Wuille
<p>Just ftr. The 1/784931 fpr is for bitcoin core and compatible. Wasabi filter's parameters are different because Wasabi wallets are expected to have more keys than average bitcoin core wallets given coinjoins and remixes.</p>

CC BY-SA 4.0
2023-02-05T19:56:23.200Z
Wasabi doesn't use BIP158 filters.
Pieter Wuille
CC BY-SA 4.0
2023-02-05T23:48:31.900Z
@PieterWuille Wasabi does use BIP158 filters AFAIU.
https://docs.wasabiwallet.io/FAQ/FAQ-UseWasabi.html#what-are-bip-158-block-filters
https://docs.wasabiwallet.io/using-wasabi/BIPs.html
yahiheb
CC BY-SA 4.0
2023-02-06T02:07:24.867Z
Well BIP158 specifies the parameters for the filter, including the 1/784931 false positive rate. It's possible it uses a (very) similar design, but IIRC at least the filter contents is different, and the parameters are different.
Pieter Wuille
CC BY-SA 4.0
2023-02-06T15:02:32.237Z
Thank you for clarifying this.
yahiheb
CC BY-SA 4.0
2023-02-05T19:50:45.257Z
2023-02-05T19:50:45.257Z
lontivero
<p>If a block has much fewer transactions than average, let’s say 63 like 4MB block <code>774628</code>, will keys have less probability to falsely match against its BIP157-8 compact filter?</p>

<compact-client-side-block-filters>
Does the probability of false positives with BIP157-8 depend on the number of TXs in the block?
Turbolay
# Does the probability of false positives with BIP157-8 depend on the number of TXs in the block?

(Asked by: username_0 on 2023-02-04)

If a block has much fewer transactions than average, let’s say 63 like 4MB block `774628`, will keys have less probability to falsely match against its BIP157-8 compact filter?

**Tags:** compact-client-side-block-filters


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## 2 answers

### Answer by username_1 on 2023-02-05. Score: 3 | Accepted answer

No, BIP158 basic filters have a fixed false positive rate of exactly 1/784931, regardless of how many elements they contain.


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### Answer by username_2 on 2023-02-05. Score: 1

Just ftr. The 1/784931 fpr is for bitcoin core and compatible. Wasabi filter's parameters are different because Wasabi wallets are expected to have more keys than average bitcoin core wallets given coinjoins and remixes.

> **Comments:**
> **username_1**: Wasabi doesn't use BIP158 filters.  
> **username_3**: @PieterWuille Wasabi does use BIP158 filters AFAIU. https://docs.wasabiwallet.io/FAQ/FAQ-UseWasabi.html#what-are-bip-158-block-filters https://docs.wasabiwallet.io/using-wasabi/BIPs.html  
> **username_1**: Well BIP158 specifies the parameters for the filter, including the 1/784931 false positive rate. It's possible it uses a (very) similar design, but IIRC at least the filter contents is different, and the parameters are different.  
> **username_3**: Thank you for clarifying this.  

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