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7 votes
1 answer
2k views

Why does BIP141 define both virtual transaction size and weight?

Why does BIP 141 (segwit) define both virtual transaction size and weight? Weight seems to be just four times virtual transaction size (or vice versa, depending on what you define first). Why are ...
3 votes
1 answer
752 views

what is measured in units of sat/kw?

Whilst learning about bitcoin & lightning fees I have encountered the abbreviation sat/kw a few times, most recently here: Why can’t lightning tx’s be signed with sighash single to allow for fee ...
1 vote
1 answer
132 views

How are the block header bytes treated when calculating the block size in weight?

In pre-segwit, block header bytes were counted as "1 byte" and participated equally in the block size up to 1MB. Since the header is 80 bytes, we would actually have 999,917 bytes (1,000,000 ...
1 vote
0 answers
180 views

Why is the discount on segWit data exactly a factor of 4 and not 5, 6 or something higher?

According to BIP141, the formula for calculating block/transaction weight is: BASE SIZE * 3 + TOTAL SIZE According to Bitcoin wiki (and also based on the above formula): Each byte of the segwit ...
23 votes
2 answers
13k views

Is there a difference between bytes and virtual bytes (vbytes)?

In an Optech newsletter, size is referred to using vbytes. Is there a difference between vbytes and bytes? If so, what is the difference?
3 votes
1 answer
215 views

What is the maximum number of taproot transactions that can be mined in a single block?

If all transactions in a block were spending one p2tr output using the key-path spend and sending to a p2tr output, how many of these transactions could we fit in a single block?
1 vote
1 answer
130 views

Why is -blockmaxweight set to 3996000 by default?

The configuration parameter -blockmaxweight in Bitcoin Core allows miners to set a maximum block weight they want to mine. Oddly, the default value of this parameter is 3996000 as opposed to the ...
4 votes
1 answer
3k views

What is the current maximum Bitcoin block size in MB?

BIP141 specifies the following: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#block-size Block size Blocks are currently limited to 1,000,000 bytes (1MB) total size. We ...
3 votes
1 answer
1k views

After Segwit Activation, what is the largest block size possible?

The code says MAX_BLOCK_SERIALIZED_SIZE = 4000000, but that is actually not a actually consensus rule as stated here: https://github.com/bitcoin/bitcoin/issues/10289 The actual consensus rule is ...
3 votes
2 answers
768 views

How much does the weight of 2-of-3 multisignature inputs differ between P2SH and P2SH-P2WSH?

I'm trying to calculate the weight of a 2-of-3 multisignature P2SH-P2WSH input. I found the related question Predict multi signature transaction size, which I've calculated with m=2, n=3 here: ...
2 votes
2 answers
202 views

What is the weight of a block that contains no pay-to-witness scripts?

I'm trying to understand block weight, a metric introduced by segwit (BIP-141): block weight = 3 * base size + total size "base size" is the length of a pre-segwit block, which contains only ...
9 votes
2 answers
2k views

How does SegWit reduce transaction size, when the signature is simply moved to another part of the transaction?

This video explains that the signature is moved out of the input section and moved to the new one called the witness. From what I can tell, the witness signature is still contained in this transaction ...
2 votes
2 answers
653 views

What happens if "transaction size" is larger than "maximum block size"?

Assuming a transaction size is T Bytes, while maximum block size is B Bytes, such that T>B. What happens for this transaction? It will be divided into two smaller parts and will be stored in two ...
3 votes
3 answers
1k views

Does the transaction fee depend on the transferred amount?

Do transaction fees depend on the amount of bitcoin sent? On what factors do fees depends?
1 vote
1 answer
67 views

Why is the block size so big, taking into account a relatively small number of transactions?

Why the size of the block 656143 is so big (Size: 2,337,727 bytes), taking into account a relatively small number of transactions (Number of Transactions: 84)? Extra question: What is the block size ...
6 votes
6 answers
1k views

Can blocks remain capped to 1MB forever?

This is perhaps more of an economics question than a bitcoin question, but I'm wondering if it would be viable to leave the block size capped at 1MB for all time and simply let a series of rules ...
3 votes
1 answer
81 views

Is it possible for the `size` and `vsize` to be the same for a valid segwit (bech32) transaction?

I'm aware that for non-segwit transactions, vsize is always the same as size. But is it possible for a valid transaction to include size=vsize when involving segwit inputs/outputs? This particular ...
3 votes
1 answer
3k views

Different fee rate units - sat/vB, sat perkw, sat perkb

While reading documentation of C-Lightning I found this in section about making onchain transactions with the wallet (funding and withdrawing the wallet): feerate is an optional feerate to use. It ...
0 votes
1 answer
240 views

Most transactions in a block

Block 689074 had 4,463 transactions. Is this the highest number of transactions in a block until now? What are the things that affect the number of transactions possible in a block? Few observations ...
9 votes
2 answers
4k views

What is block weight and how is it different from block size?

While reading about BIP141, I have encountered the following options: Block creation options: -blockmaxweight=<n> Set maximum BIP141 block weight (default: 3000000) -blockmaxsize=<n> ...
1 vote
1 answer
540 views

Concept of Block weight and segwit are still unclear

It seems like duplicated question, but i read many articles and posts to undestand about segwit. Below links are something i read What is block weight and how is it different from block size? After ...
4 votes
2 answers
548 views

On chain cost of Segwit version 1 versus version 0

How do total blockchain cost for Segwit version 0 compare to version 1 which is being proposed? I'm specifically interested in a single user transactions – both paying to public key (or pk hash) and ...
1 vote
1 answer
83 views

Can SegWit block weight be increased without a hard fork?

I know segwit's block weight is 4MB. Can it be increased without a hard fork? If no, was that option even considered, and is it even possible?
1 vote
1 answer
263 views

What is the maximum size for SegWit transactions?

Before SegWit was activated, transactions were limited to 100,000 bytes or 100 kB. Bigger transactions were non-standard. What is the limit for transaction size after the activation of SegWit? Is ...
1 vote
1 answer
454 views

How much will Segwit *actually* increase bitcoin capacity for realistic transactions?

I often see claims that Segwit increases transactions per block by 1.7x to 2x. I'm not sure if this is true, but if I do the math myself, I don't get this number. My understanding is: 1) The “weight”...
5 votes
1 answer
925 views

Why does the Segwit developer guide recommend to estimate fees on basis of vsize instead of weight?

The Segwit Wallet Development Guide has a small section on fee estimation: Transaction Fee Estimation Instead of transaction size, a new metric is defined, called “virtual size” (vsize) ...
3 votes
1 answer
114 views

Do sigops count towards the block weight in SegWit?

I was just rereading the SegWit benefits page and noticed that the section Moving towards a single combined block limit contains an example in which sigops count towards the blockweight. Did this ...