Where the figure comes from
The page asks the chain's transaction payment API, the same one wallets use. The fee depends on the call's weight (the work it does), its length in bytes, and the chain's current fee multiplier.
When the actual fee differs
- A tip is paid on top of the fee.
- Some staking calls can pay the fee in alpha instead of τ. The chain then converts the τ figure at the subnet's price, so the alpha taken can differ from a straight conversion.
- Calls through a proxy can be paid by the proxied account, if it chose to pay its delegates' fees.
- The fee multiplier moves with how full blocks are, so a later estimate can differ slightly.
Amounts in the common calls only shape the call; the fee barely depends on them.