A token’s decimal setting tells your wallet how to display its smallest whole-number units. If a bridge moves value between token versions with different decimal settings, the destination may not represent every tiny fraction.
- Token balances are stored as whole numbers; decimals control how those numbers appear.
- A destination with fewer decimals can require rounding down, leaving a tiny remainder unrepresented.
- Check the token versions and their decimals on both networks before moving a precise amount.
What do token decimals change?
Decimals set the scale for reading a token balance, rather than making the token divisible in its contract code. For a token with six decimals, 1,000,000 stored units display as 1 token; with 18 decimals, 1 token is 1,000,000,000,000,000,000 units.
The ERC-20 standard describes decimals as display information. In practice, wallets such as MetaMask use that value to turn the contract’s whole-number balance into an amount you can read. The token’s contract still transfers whole units.
Where can precision loss happen?
Precision loss can happen when a bridge converts an amount from a token version with more decimals to one with fewer. The destination cannot show or represent fractions smaller than its own smallest unit, so a conversion may round down or reject an amount that does not fit.
For example, imagine a source token with 18 decimals and a destination version with 6. A transfer of 12.3456789 source tokens equals 12,345,678,900,000,000,000 source units. The destination can represent 12.345678, but not the extra 0.0000009 token.
That tiny remainder is sometimes called dust: a fraction too small to represent on the destination token. What happens to it depends on the bridge’s conversion rules. It might remain on the source side, be rounded down, or cause the transfer to fail; there is no single rule for every bridge.
How does this relate to a Polygon transfer?
A bridge links token versions on separate networks. In the Polygon PoS bridge model, tokens deposited from Ethereum are locked there while a mapped version is minted on Polygon; withdrawals burn that version before the original is released. The Polygon PoS documentation describes this lock-and-mint, burn-and-release flow.
When the two versions use the same decimals and the bridge preserves the amount, the decimal setting alone does not create a loss. Polygon Bridge is a concrete example of a route between Ethereum and Polygon, where checking the token versions helps explain any difference you see.
Before moving funds from an exchange-style balance to your own wallet, check the token’s decimal setting on each network. You can find it in the token contract’s decimals value, when available, or in reliable token information. Also compare the token contract addresses: matching names and symbols do not prove that two tokens are the same asset.
What should you do before sending?
First, decide how many whole tokens you want to arrive, then check whether the destination version can represent that amount. If you are moving a small balance or need an exact amount, test the conversion with the token’s decimal difference in mind.
The bridge transfer itself may also require network gas, which is separate from any precision difference. A small amount can be affected more noticeably by rounding because the unrepresented fraction is a larger share of the total.
FAQ
Does a different decimal count mean the token is worth less?
No. Decimals describe how a token balance is displayed and divided into units; they do not set its market value. A token with six decimals can have the same value per whole token as a version with 18 decimals. The important question is whether the bridge maps the two versions correctly and how it handles amounts between their smallest units.
Can MetaMask show a different balance after bridging?
It can show a balance with a different number of decimal places if the destination token has a different setting. First check that you are viewing the intended network and token contract. Then compare the actual amount received with the bridge’s conversion rule; a display difference by itself does not prove that value was lost.
How can I avoid losing a tiny fraction?
Check both token versions and their decimals before sending, especially when transferring a very small amount or an exact balance. If the destination has fewer decimals, choose an amount that converts into whole destination units. For a Polygon move, the Polygon Bridge transfer is one way to move tokens between Ethereum and Polygon. Match the decimal scales first; then confirm the amount you expect to arrive.
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