Kaspa uses a “mass” model. Transactions have a mass measured in grams.
Fees are feerate (sompi/gram) × mass (grams). The minimum relay fee is typically
1 sompi/gram, rising when network load increases.
Sompi is the smallest unit of KAS (like satoshis).
“Sompi/gram” is the feerate unit: how many sompi you pay for each gram of transaction mass.
When the mempool grows and blocks are near their mass limits, a fee market kicks in.
Higher feerates help your transaction get included sooner.
At minimum feerate (1 sompi/gram), a regular wallet send often costs around
a few ten-thousandths of a KAS, depending on how many UTXOs are being spent.
Fees scale with mass. You can lower mass by consolidating UTXOs (spending fewer inputs),
or waiting for quieter network conditions and using the economy feerate bucket.
Recent kaspad updates add RBF support so wallets/exchanges can rebroadcast
with a higher feerate if needed.