Should I add loads of decimals?

[Warszawa]

When sending a transaction between wallets I own is it best practise to add lots of decimals? For example instead of sending 0.0042 btc, I should send 0.004268942?

My hardware wallet links to Blockstream.info as explorer, and on it's privacy analysis it flags "Round Payment Amount" warning.

There is a link to https://en.bitcoin.it/wiki/Privacy#Round_numbers and indeed I have been trying to read the whole article, it's uber coprehensive, but complex (and a bit TLDR)!

Also a bit scary (I don't use a VPN and checking an explorer from IP can footprint to my bitcoin addresses) and also awe inspiring at the sheer technical scope and development that goes into bitcoin - my appreciation and love for bitcoin continues to grow every year!

[BlackHatCoiner]

For example instead of sending 0.0042 btc, I should send 0.004268942?

Well, once you create a non-round amount of bitcoins output, you surely have a better privacy. Although, it's not always true. For example, there are times when you actually need to send a round amount and you're obviously not the receiver. But if you do want to ensure that you'll not be successfully traced, then just split the amount to 2+ addresses.

Bad transaction:
A sends 0.1 bitcoins to B.

Good transaction:
A sends 0.02574196 bitcoins to B and 0.07425804 bitcoins to C.

(Where B and C your addresses)

Even better transaction for your privacy:
(You establish a peer-to-peer connection through tor where you and another person(s) sign your inputs and broadcast it as one transaction. Thus, no one knows who has what.)

CoinJoin^[1] transaction: (Usually created with Wasabi^[2])

• You connect with Bob through tor.
• You sign your inputs.
• Bob signs his inputs.
• You and Bob broadcast it as one transaction.
• The outputs' owners are unknown and you and Bob have successfully mixed your coins together.

[1] CoinJoin
[2] Wasabi

[o_e_l_e_o]

When sending a transaction between wallets I own is it best practise to add lots of decimals? For example instead of sending 0.0042 btc, I should send 0.004268942?

The privacy risk with round number payments is that usually (but not always) the round number is a payment to someone else. This means that the other non-round output in the transaction is usually the change. This allows someone looking at the blockchain to see which output is a payment, which output is change, and link the change address to the input address.

Now, if you are sending money between your own wallets, then there are other things to consider too. If you spend an input (or all the inputs from one address) in full and send them to another address, then that is also usually an indicator that the two addresses belong to the same person (or the output address is a deposit address at an exchange or other service belonging to that person's account).

Also a bit scary (I don't use a VPN and checking an explorer from IP can footprint to my bitcoin addresses)

Just use Tor to look up your addresses on a block explorer then. It's free and better for anonymity than a VPN anyway.