Cardano vs Bitcoin & Ethereum transaction speeds and fees

Can anyone answer this question? Let’s say I go to a gas station in March 2021 that accepts Bitcoin, Ethereum, and Cardano. I want to buy a $1 candy bar during a time when all three networks are congested. How much would it cost and how long would the transaction take? I’m not sure how many confirmations the gas station would accept so please give me a range.

I would like to make a chart that compares these three cryptocurrencies for transaction speed and fees when the network is congested and when it’s not. It is very hard to find accurate information on the web to make a fair and unbiased comparison. I could buy from an exchange $1 worth of all three cryptos and “time it” but that would only give me only a moment in time. Any help or advice is appreciated! Thanks!

There are differences between micropaymetns and large payments.
Youd would not need too many confirmations for a 1$ micropayment but for a 1m$ you want to be sure you got enough confirmations. Afaik 3k/f or 4k/f confirmations so no instant confirmation atm, but it will be introduced in Hydra, though it has an almost instant confirmation but in OBFT mode only.

For micropayments, how I imagine it, the merchants have it’s bundled cardano-node in their app or back in the office, and when you scan it it will be almost instant as a merchant would not bother with 1$ tx to be settled in a block and waited for confirmation. It means, if his/her nodes accepts it that means the UtxO was valid at that time in his node’s of PoV.

Currently, Cardano can handle max ~270 average-sized txes per 64KB block, meaning 15txs per second, which can be scaled up to ~270 tps, but that’s very unrealistic. I would say 60 tps for average sized txes are realistic even 120. But, only assuming average sized txes (no smart contracts, not metadata, no huge token bundles etc.).

Also, it currently costs you ~20cents, but it can be readjusted any time by voting.

The network is congested? Then you cannot predict any confirmation as it depends on characteristic of the congestion, so pls be more specific.

Anyway, I assume that tx was accepted by the node meaning it’s mempool contains that unspent tx and broadcast it to the network. But for how long it’s unpredictable, despite the fact that every nodes have a double sized (~128KB) mempool compared to the max block-size (~64KB) we cannot be sure which leader would have that tx in its mempool to include in its newly created block. So, who knows.

I think you need to dig a bit deeper into the nitty-gritty details of how blockchains work to have educate questions.


Thank you very much for your response, I learned so much!