Guides · Safety ·

Swap on TON: quote, slippage, router and fees

A swap in Gram Wallet is a single message from your wallet to a STON.fi router contract; Tongram is not an exchange and holds nothing in between. The quote you see comes from the STON.fi simulate API and shows the rate, the minimum you will receive at your slippage setting (0.5, 1 or 3 percent), the price impact, the DEX fee, the router version and address, and the age of the quote.

A quote older than 60 seconds cannot be confirmed; refresh it. On v2 routes a 0.30 percent wallet fee is taken from the received token and is already subtracted from the amounts shown.

Once broadcast, a swap cannot be reversed.

Open Gram Wallet

What this covers

  • Covers the Swap sheet in Gram Wallet for GRAM and jettons routed through STON.fi on mainnet.
  • Covers what the numbers on the sheet mean and where they come from. It does not predict prices or recommend tokens.
  • Does not cover other DEXes, aggregators or centralised exchanges; Tongram routes only through STON.fi.

Steps in Tongram

  1. Open Wallet, then Swap. Pick the token to pay with and the token to receive from the list; Max leaves about 0.3 GRAM aside for gas when paying in GRAM.
  2. Enter an amount. After a short pause the quote appears: rate, router, minimum received, price impact and DEX fee, plus the wallet fee line when the route is v2.
  3. Choose slippage: 0.5, 1 or 3 percent. Lower means a tighter floor and a higher chance the swap does not go through if the pool moves; higher accepts a worse fill.
  4. Read price impact. A large value means your amount is big relative to the pool and you are moving the price against yourself.
  5. If either token is marked as charging a transfer tax, expect to receive less than quoted; the tax is applied by the token contract, not by STON.fi or Tongram.
  6. Press Swap to open Review. The exact message is signed locally and emulated, and the sheet shows the outcome, minimum received, slippage, router and quote age.
  7. Confirm while the quote is under 60 seconds old. If the counter has run out, go back and refresh; the button stays disabled until then.
  8. Wait for the result. Done means the wallet seqno advanced; Queued means the network has not confirmed yet and you should check the transaction in the explorer before trying again.

What you see and where it comes from

  • Fact: rate, minimum received, price impact, DEX fee, pool and router come from the STON.fi simulate endpoint for the exact pair, amount and slippage you entered. Tongram does not compute a price of its own.
  • Fact: the swap message is built with the STON.fi SDK for the router version the quote names (v1, v2.1 or v2.2). An unrecognised version is refused instead of guessed.
  • Fact: the wallet fee is 0.30 percent of the received token on v2 routes, collected by the router into a vault owned by Tongram. v1 routes carry no wallet fee. The quoted and minimum amounts already have it subtracted.
  • Fact: the token list is limited to assets STON.fi tags as default, essential, or popular with high liquidity, and excludes blacklisted or deprecated entries. GRAM is identified by kind, never by ticker.
  • Interpretation: minimum received is a floor handed to the router. What happens when the pool cannot meet it is decided by the STON.fi contracts; their documentation describes returning the offered asset rather than filling below the floor.

Freshness and limits

  • A quote is a snapshot. Pools move between the quote and on-chain execution; the fill can be anywhere between the quoted amount and the minimum.
  • The 60-second limit is a Tongram rule, not a protocol one. It exists because an old floor is a bad floor; the router itself does not know when you were quoted.
  • Gas is paid in GRAM on top of the swapped amount and is set by the STON.fi SDK for the route. The emulated outcome shows the expected total; the actual fee is known only after execution.
  • Unknown: the exact received amount for tokens with a transfer tax, and the behaviour of any jetton that is not a standard TEP-74 contract.
  • A swap that has been broadcast cannot be cancelled or undone. A swap that bounces returns funds per the router logic, minus network fees.

Common mistakes

  • Confirming a stale review sheet. Tongram blocks this after 60 seconds, but a quote 55 seconds old on a fast-moving pair can still fill near the minimum.
  • Setting 3 percent slippage on a large amount because the swap kept bouncing. Look at price impact first; the pool may be too shallow for the size.
  • Swapping the whole GRAM balance. Without gas left the transaction fails; use Max, which keeps a reserve.
  • Judging a token by its ticker. The list filters look-alikes, but the jetton master address is what identifies a token; verify it in the explorer.
  • Reading the quoted amount as a promise. It is the mid-point of a simulation; the minimum is the only number the router enforces.

Sources

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