# Token Units and Decimals Source: https://docs.chain.link/ccip/evm/concepts/cross-chain-token/rate-limits/token-units-and-decimals Last Updated: 2025-06-09 > For the complete documentation index, see [llms.txt](/llms.txt). > **NOTE: CCIP 2.0** > > This page applies to manual onchain configuration and deployment tooling output. **v1.x pools** differences are noted > inline. When you configure CCIP rate limits, you specify onchain values in the token's **smallest unit** on the chain where the pool is deployed, not in whole tokens. Incorrect unit handling can result in rate limits orders of magnitude larger or smaller than intended. ## Smallest unit vs human-readable amounts A token's decimals determine its smallest unit: - An 18-decimal token (for example, LINK or ETH) uses `10^18` base units per token - A 6-decimal token (for example, USDC or USDT) uses `10^6` base units per token Rate limit parameters such as capacity and rate must always be provided in these base units when you submit onchain transactions. ## Local denomination on each chain You set outbound limits on chain A and inbound limits on chain B in **separate transactions**, each scaled to **that chain's decimals**. Do not copy a base-unit value from one chain to another unless decimals match and you intend identical limits. > **NOTE: v1.x pools (EVM, pre-v1.6.1)** > > Inbound limits on some legacy pools were denominated in **remote/source decimals** rather than local destination > decimals. Pools at **v1.6.1 and later** use local denomination, same as v2.0. Always inspect onchain state. ## Converting values for onchain configuration To convert a human-readable token amount into the value used onchain, apply the following formula: ``` On-chain value = human-readable amount × (10 ^ local token decimals) ``` This conversion applies to: - capacity values - refill rate values Use the decimals of the **chain where you are submitting the transaction**. ## Example: 18-decimal token Token on Ethereum mainnet: - Decimals: 18 - Desired outbound capacity: 100 tokens Calculation: ``` 100 × 10^18 = 100000000000000000000 ``` The capacity value passed to the token pool contract on Ethereum must be `100000000000000000000`. If the token also uses 18 decimals on the remote chain, the counterpart inbound capacity is typically **110%** of the outbound value, for headroom: ``` 110 × 10^18 = 110000000000000000000 ``` That inbound value is configured on the **destination** pool, not the source. ## Example: 6-decimal token Token that uses 6 decimals on the local chain: - Decimals: 6 - Desired outbound capacity: 500 tokens Calculation: ``` 500 × 10^6 = 500000000 ``` The capacity value passed to the token pool contract must be `500000000`. ## Cross-decimal lanes If the same logical token uses different decimals on two chains, compute each side of the lane with that chain's **local decimals**. Do not reuse a base-unit value from one chain on another. ## Common failure modes The most common causes of misconfiguration include: - assuming values are specified in whole tokens - applying the wrong decimal precision - copying a base-unit value from the source chain onto the destination chain without rescaling - copying example values without recalculating for the target token Any of these mistakes can: - unintentionally block transfers - allow far more volume than expected - create operational risk that is difficult to detect immediately ## Before updating rate limits Before submitting any transaction that updates rate limits: - verify the token's decimal precision on **each chain** in the lane - recompute capacity and rate values from the human-readable amounts - double-check values in base units - confirm the inbound limit on the destination provides adequate headroom (typically ≥ 110% of source outbound) Once values are submitted onchain, they take effect immediately and the bucket is refilled to full capacity. > **NOTE: v1.x pools** > > Values take effect immediately, but the bucket refills at the normal rate instead of jumping to full capacity. ## What's next After validating units and conversions, you can proceed to [updating inbound and outbound rate limits](/ccip/evm/concepts/cross-chain-token/rate-limits/update-rate-limits) for the selected token pool and lane. > **CAUTION: Disclaimer** > > Chainlink CCIP is an interoperability messaging protocol. Chainlink does not hold or transfer any assets. The > performance and behaviour of applications using Chainlink CCIP may depend on coding, engineering, configuration, and > other technical implementation choices made by developers, token issuers, Cross-Chain Verifiers, and other > participants. Users remain responsible for evaluating, configuring, testing, deploying, operating, and maintaining > their own applications and integrations, including assessing any applicable operational, security, technical, and > legal or regulatory risks. Please review the [Chainlink Terms of Service](https://chain.link/terms) which provides > important information and disclosures. By using Chainlink CCIP, you expressly acknowledge and agree to accept these > terms. Cross-Chain Verifiers (CCVs) may be operated by third parties. The security, availability, governance, and > operational profile of a CCV varies depending on the verifier selected. Users are solely responsible for evaluating > any CCVs used in connection with their applications or integrations and determining whether they are appropriate for > their intended use case. This code represents an example of using a Chainlink product or service. It is provided "AS > IS" and "AS AVAILABLE" without warranties of any kind, has not been audited, and may omit checks or error handling. > Each party intending to use this reference implementation must perform its own audits, security and code review, and > testing before any production deployment and ensure the operation and performance of such code matches expectations. > Neither Chainlink Labs, the Chainlink Foundation, nor Chainlink node operators are responsible for outcomes due to > errors in this example or how it is deployed or operated. Use of the Chainlink Network is subject to the Chainlink > Foundation Terms of Service, which provides important information and disclosures. By using this code, you acknowledge > and agree to these terms.