BNB Chain gas and fees explained
BNB Chain (BSC) is chain id 56. Gas is paid in BNB, blocks are about 0.75 s apart, and the going gas price is 0.05 gwei - a transaction costs a fraction of a cent.
Getting BNB
BNB from any exchange withdraws straight to BNB Chain (pick the "BSC" or "BEP20" network). Holding USD1 or another asset does not pay for gas; the API's insufficient_funds error spells this out because it is the most common first-run problem.
What a trade costs
| Typical gas | At 0.05 gwei | |
|---|---|---|
| Buy on the curve, BNB-priced | ~500k | ~0.000025 BNB |
| Buy on the curve, USD1-priced (Flap swaps for you) | ~1.1M | ~0.000055 BNB |
| Buy on PancakeSwap after graduation | ~900k | ~0.000045 BNB |
| One-time approval | ~50k | ~0.0000025 BNB |
Flap's contracts do a lot per trade (tax accounting, liquidation checks, mirror pairs for indexers), so the gas figures are high for what they are - and still cost well under a cent each.
What a launch costs
Flap charges nothing to create a token. A tax-token launch is about 7 million gas, around 0.00035 BNB; a standard token is lighter. Plus your dev buy, if any.
Why the wallet needs more than the trade amount
A node reserves gasLimit x maxFeePerGas before running a transaction and refunds what is unused. The API pads the gas limit by 20% and sets the fee ceiling at 1.25x the current gas price, so the reservation is about one and a half times what is actually spent. A wallet holding exactly the trade amount plus the expected gas is rejected. The API checks this before you sign, sums the whole batch when there is an approval in front, and tells you the figure to hold.
A practical rule: keep 0.002 BNB in a trading wallet on top of what you trade with. At BNB Chain's prices that covers hundreds of trades.
Where the fees go
- Gas to the validators.
- Flap's curve fee to Flap; the tax to the token's creator - see Creator Revenue.
- PancakeSwap's LP fee to the pool, on graduated tokens.
- 0.5% to shrine.trade.
Full list on Fees.