---
title: Why small swaps cost more in percent: fees and limits
description: A fixed network fee is a large share of a small payout and a small share of a large one. The algebra, a worked illustration and how to read the form.
url: https://sablebolt.io/blog/minimums-maximums-network-fees-small-swaps
---

[How swaps work](https://sablebolt.io/blog)

# Minimums, maximums and fees: why small swaps cost more in percent

Sablebolt Team 28 October 2026 9 min read

Contents

1. What the form subtracts, and what it does not
2. The algebra
3. A worked illustration
4. Which payout networks are usually the expensive ones
5. How to read "You get"
6. Why the minimum exists
7. Choosing an amount with the fee in mind
8. Checklist before a small swap
9. FAQ

Every pair page on sablebolt.io shows three numbers next to the amount you type: a minimum for the route, a maximum for the route, and a network fee that is already subtracted from the "You get" line. People read the first two as rules and the third as a detail. This guide turns them around: the network fee is the number that decides whether a small swap makes sense, and the minimum exists because of it.

There are no live figures in this text. The form shows the real minimum, maximum and fee for the route you pick, and they change. The numbers below are round, hypothetical and labelled as an illustration; they are here so the arithmetic is easy to follow, not because any route costs that much.

## What the form subtracts, and what it does not

A swap on sablebolt.io has one rate and one network fee, as the [fees page](https://sablebolt.io/fees) sets out. The rate converts what you send into the receiving coin. The network fee is what the receiving network charges to deliver the payout, it is quoted in the receiving coin, and it comes out of the payout. Your own wallet's sending fee is a third cost, paid by you to the network you send from; the swap never sees it and the form does not show it.

| Cost | Who charges it | Where you see it |
|---|---|---|
| The rate | Set by the market at the moment your deposit confirms | "Rate" in the form, refreshed every 60 seconds |
| The payout network fee | The receiving network | "Network fee … included" in the form, in the receiving coin |
| Your sending fee | The network you send from, paid from your wallet | In your wallet, not on the site |

The word "included" matters. "You get" is already net of the network fee. You do not subtract it a second time, and you do not add it to what you send.

## The algebra

Call the amount you send **A** , the rate **r** (how many units of the receiving coin one unit of the sent coin buys at confirmation), and the payout network fee **f** , in units of the receiving coin. Then:

- Gross conversion: **A × r**
- What arrives: **A × r − f**
- The fee as a share of the gross conversion: **f ÷ (A × r)**

The last line is the whole point of this post. **f** does not depend on **A** . The network charges the same to deliver a small payout as a large one, because it is paid for a transaction, not for a value. So as **A** gets smaller, the share **f ÷ (A × r)** gets larger, and at some point it reaches 100 %: the fee eats the entire payout and nothing arrives. The minimum for the route sits well above that point.

Two consequences follow directly:

1. The same route costs different percentages to different people. It is not a different fee; it is the same fee divided by a different amount.
2. Doubling the amount halves the fee's share. There is no other way to shrink it on a given route, apart from choosing a route whose payout network charges less.

≈ 2–5 min 1 confirmation on TRON

[Swap USDT TRC-20 to USDT ERC-20](https://sablebolt.io/swap/usdt-trc20/usdt-erc20)

## A worked illustration

Take a stablecoin-to-stablecoin route so the rate stays out of the way: say the rate is 1.00 and the payout network fee is **3 units** of the receiving coin. This figure is invented for the arithmetic; it is not any route's real fee.

| You send (A) | Gross (A × r) | Fee (f) | Arrives (A × r − f) | Fee as share of gross |
|---|---|---|---|---|
| 20 | 20 | 3 | 17 | 15.0 % |
| 50 | 50 | 3 | 47 | 6.0 % |
| 100 | 100 | 3 | 97 | 3.0 % |
| 300 | 300 | 3 | 297 | 1.0 % |
| 1,000 | 1,000 | 3 | 997 | 0.3 % |
| 3,000 | 3,000 | 3 | 2,997 | 0.1 % |

One fee, six amounts, a share that runs from 15 % to a tenth of a percent. Now change the payout network and keep everything else. Say a second route delivers on a network whose fee is **0.05 units** in this illustration:

| You send (A) | Fee (f) | Arrives | Fee as share of gross |
|---|---|---|---|
| 20 | 0.05 | 19.95 | 0.25 % |
| 100 | 0.05 | 99.95 | 0.05 % |
| 1,000 | 0.05 | 999.95 | 0.005 % |

For a 20-unit swap the choice of payout network is the difference between losing a sixth of it and losing a quarter of a percent. For a 3,000-unit swap the difference is barely visible. That is why "which network is cheap?" is mostly a small-swap question.

## Which payout networks are usually the expensive ones

The form shows the exact fee for your route at the moment you look. What can be said in general, without a number, is which networks tend to sit at which end.

| Payout network | Fee level, as a rule | Why |
|---|---|---|
| Ethereum (ETH, USDT ERC-20, USDC ERC-20) | Usually the highest among the networks here | Each transaction pays for block space on a busy chain; the fee rises with congestion |
| Bitcoin | Usually high, and variable | Block space is scarce and the fee market moves with demand |
| Litecoin, Dogecoin, Zcash, Monero | In between | Less contested block space than Bitcoin or Ethereum |
| TRON (USDT TRC-20, TRX) | Usually low | Transfers are paid in resources and the per-transfer cost is small |
| BNB Smart Chain (USDT BEP-20, BNB) | Usually low | Short blocks, cheap gas |
| Solana (SOL, USDC on Solana) | Usually low | Transaction fees on Solana are small |
| TON (USDT on TON, GRAM) | Usually low | Transfer fees on TON are small |

The fee level of the payout network is what counts, not the network you send from: on [USDT TRC-20 → USDT ERC-20](https://sablebolt.io/swap/usdt-trc20/usdt-erc20) the payout is on Ethereum and the fee is an Ethereum fee, however cheap TRON was to send from. And "usually" means usually: Bitcoin and Ethereum fees can be low on a quiet day, and the form shows it when they are.

## How to read "You get"

The form has four lines that belong together, and reading them in order avoids most surprises.

1. **Min** next to the form's title: the smallest amount the route accepts, in the coin you send. Below it the form refuses with "The minimum for this route is …".
2. **You get (estimate)** : the payout after the network fee, at the rate of this moment. It refreshes every 60 seconds while the page is open.
3. **Network fee … included** : the fee in the receiving coin. "Included" means it is already inside "You get".
4. **Arrival** : the time the route usually takes, driven by the confirmations the sending network needs.

Once a quote is loaded, the pair page also shows a block called "What this swap costs right now": what you send, what arrives, and the network fee that was taken out. The three lines are consistent with each other by construction; if you want to check the share for your own amount, divide the fee by what you send plus the fee, both in the receiving coin.

**The fee is in the receiving coin, not the sent one.** On [USDT TRC-20 → BTC](https://sablebolt.io/swap/usdt-trc20/btc) the fee is a few units of BTC, shown with eight decimals. To compare it with the amount you send, multiply by the rate shown. A fee that looks tiny because it starts with several zeros may still be a noticeable share of a small swap.

## Why the minimum exists

The minimum is the route's answer to the arithmetic above. Below some amount the payout, after the fixed fee, would be too small to be worth delivering, and at an even smaller amount it would be zero or negative. A route therefore refuses amounts under its minimum rather than accept a deposit it cannot pay out sensibly.

That also explains why minimums differ from route to route. A route that pays out on Ethereum or Bitcoin needs a higher floor than one that pays out on TRON or Solana, because its fixed fee is larger. The minimum is quoted in the coin you send, next to the form title, and the API endpoint `/v1/limits` returns the same two values, `min` and `max` , for anyone reading the site by machine.

The maximum is the other bound: the largest amount a single swap on this route can be created for at that moment. If your amount is above it, the form says so with "The maximum for this route is …".

## Choosing an amount with the fee in mind

A short decision procedure, using the form rather than guesses:

1. Type the amount you actually want to send and read the fee line.
2. Divide the fee by the gross conversion (what you get plus the fee). If the share is larger than you are willing to pay, you have two levers.
3. **Lever one: amount.** Send more in one swap and the share falls in proportion. Two swaps of 100 pay the fee twice; one swap of 200 pays it once.
4. **Lever two: route.** If the receiver can accept the token on a cheaper network — USDT on TRON, BNB Smart Chain, TON or USDC on Solana instead of Ethereum — the fee drops sharply. Ask the receiver first; a token sent to the wrong network is not a fee problem, it is a recovery problem.

For a receiver who can take USDT on several networks, [USDT TRC-20 → USDT BEP-20](https://sablebolt.io/swap/usdt-trc20/usdt-bep20) and [USDT TRC-20 → USDT on TON](https://sablebolt.io/swap/usdt-trc20/usdt-ton) are the routes where the fee line is usually smallest in this illustration's sense; the form confirms it for the moment you are looking.

## Checklist before a small swap

- The amount you typed is above the route's "Min" and the form shows no warning.
- You read the fee line in the receiving coin and worked out its share of your amount.
- You compared that share with a cheaper payout network, if the receiver can accept one.
- You know that "You get" already has the fee taken out, so the receiver gets that figure, not that figure minus the fee.
- You remembered your own wallet's sending fee, which is on top and not shown on the site.
- You are sending the exact amount the estimate was made for, in one transaction.

## FAQ

Is the network fee a Sablebolt fee?

No. It is what the receiving network charges to deliver the payout, quoted in the receiving coin and shown before you send. What the price is made of is listed on the [fees page](https://sablebolt.io/fees) .

Why is the fee the same whether I send 20 or 2,000?

Because the network charges per transaction, not per value. The payout transaction is the same size either way, so the fee is the same and its share of your swap is not.

Why does the minimum differ between routes?

The minimum protects the payout from being swallowed by the fixed fee. Routes that pay out on networks with high fees need a higher floor than routes that pay out on TRON, BNB Smart Chain, Solana or TON.

Can I avoid the fee by picking a different sending network?

No. The fee belongs to the receiving network. Changing where you send from changes your wallet's sending fee and the confirmation time; changing where the payout lands changes the fee the form shows.

The fee looks like 0.0000x and seems tiny. Is it?

Convert it with the rate shown. A fee in BTC or ETH has many leading zeros but can still be a noticeable share of a small swap. The share is fee ÷ (what you get + fee).

Does the fee change between the estimate and the payout?

It can, on networks whose fee level moves with congestion, such as Ethereum and Bitcoin. On TRON, BNB Smart Chain, Solana and TON it is small and steady. How the final amount is set is explained in the [how it works](https://sablebolt.io/how-it-works) page.

## Related posts

- [How swaps work Floating rate: what changes between the estimate and the payout The estimate is a snapshot and the payout is set when the deposit confirms. What happens in between, with numbers. 18 October 2026 7 min](https://sablebolt.io/blog/floating-rate-estimate-vs-payout)
- [USDT between networks USDT network fees compared: TRON, BNB Smart Chain, Ethereum, TON, Solana A dated snapshot of what one USDT transfer burns on five networks, how each fee is calculated, and which fee token you must hold to move the money on. 22 October 2026 12 min](https://sablebolt.io/blog/usdt-network-fees-compared)
- [How swaps work Reading a swap status page: every state from waiting to finished Waiting, Confirming, Swapping, Sending, Done — what each stage means, which hash to look up where, and when a wait is normal. 19 October 2026 9 min](https://sablebolt.io/blog/reading-a-swap-status-page)