How to Use Hex ↔ Decimal

Ethereum calldata, logs, and storage use hex; developers think in decimal (uint256). The Hex ↔ Decimal converter converts between hex and decimal uint256-style integers so you can decode calldata, logs, and on-chain values—and encode decimal numbers to hex for contract parameters. All conversions run in your browser with no data sent to any server.

What does the Hex ↔ Decimal / Uint256 Converter do?

This tool converts hexadecimal values to decimal (uint256) numbers and vice versa, making it easy to interpret Ethereum calldata, logs, and on-chain values. Paste hex (with or without 0x) to get decimal; enter decimal to get hex suitable for smart contracts and logs. It supports full 256-bit (uint256) values, matching the maximum size used in Ethereum smart contracts. All conversions are performed locally in your browser. Use it to decode uint256 values from calldata or logs, or to encode decimal numbers to hex for contract parameters.

Key Features

• Hex ↔ decimal — Converts hex to decimal (uint256) and decimal to hex. For calldata, logs, and on-chain values.
• Hex to decimal — Paste hex (with or without 0x). Tool displays equivalent decimal (uint256).
• Decimal to hex — Enter decimal (uint256). Tool outputs hex for contracts and logs.
• Size — Full 256-bit (uint256) supported. Matches Ethereum smart contract max.
• Privacy — All conversions are performed locally in your browser. No data is sent to any server.
• When to use — Decode uint256 from calldata/logs; encode decimal to hex for contract parameters.

How to Use the Hex ↔ Decimal Converter

1. Open the Hex ↔ Decimal tool.
2. To convert hex to decimal: paste hex (with or without 0x). To convert decimal to hex: enter decimal value. Copy the result.
3. Use the "Use tool" button on the docs page if you are reading this from the documentation.

Real Use Cases

• Decode calldata — First 4 bytes are function selector; rest can be uint256 params. Decode each 32-byte chunk to decimal. Use with Hex-Text Converter, Keccak256 Hasher, and Eth Unit Converter.
• Decode logs — Event indexed params and data are often uint256. Convert hex to decimal for readability. Use with ABI Encoder & Decoder.
• Encode contract params — Encode decimal amounts or IDs to hex for contract calls. Use with ABI Encoder & Decoder and Eth Unit Converter.
• Documentation — Show team how hex maps to uint256. Use output as reference.
• Debugging — Read storage or return data as hex; convert to decimal to verify. Use with Wei ↔ Gwei ↔ ETH when values are amounts.
• Indexers — Decode on-chain numbers from hex to decimal for APIs or DB. Use with Hex-Text Converter for string fields.

Why Use the Hex ↔ Decimal Converter Instead of Alternatives?

• vs. Hex-Text Converter — Hex-Text Converter converts hex to UTF-8 text. This tool converts hex to decimal numbers. Use text for strings; use this for uint256.
• vs. Keccak256 Hasher — Keccak256 Hasher hashes data. This tool converts hex ↔ decimal. Use the right tool for the task.
• vs. Eth Unit Converter — Eth Unit Converter converts Wei, Gwei, ETH. This tool converts raw hex ↔ decimal. Use eth-unit for amounts; use this for any uint256.
• vs. Manual — No need to handle big integers by hand. Paste or type, get the other form.

Benefits for EVM Developers

• Developers — Decode calldata and logs. Encode decimal params to hex. Full uint256 range in the browser.

Common Mistakes

• Expecting text — This tool is for numbers (uint256). For hex ↔ text use Hex-Text Converter.
• Wrong length — Calldata params are often 32 bytes (64 hex chars). Paste full value for correct decimal.
• Signed vs unsigned — Tool handles uint256. For negative numbers or other types use ABI Encoder & Decoder.
• Forgetting to copy — Copy the result before closing the tab.

Frequently Asked Questions

What does the Hex ↔ Decimal / Uint256 Converter do?

This tool converts hexadecimal values to decimal (uint256) numbers and vice versa, making it easy to interpret Ethereum calldata, logs, and on-chain values.

How do I convert hex to decimal?

Paste your hexadecimal value (with or without 0x prefix) and the tool will instantly display the equivalent decimal (uint256) value.

How do I convert decimal to hex?

Enter your decimal (uint256) value and the tool will convert it to a hexadecimal string, suitable for Ethereum smart contracts and logs.

Is there a size limit for conversions?

The converter supports full 256-bit (uint256) values, matching the maximum size used in Ethereum smart contracts.

Is my data secure when using this converter?

Yes. All conversions are performed locally in your browser. No data is sent to any server, ensuring your privacy.

When should I use the hex–decimal converter?

Use it to decode uint256 values from calldata or logs, or to encode decimal numbers to hex for contract parameters.

Conclusion and Try the Tool

Hex ↔ Decimal gives you uint256 conversion in one place: paste hex or enter decimal, get the other. No server, no account. For text use Hex-Text Converter, for hashing use Keccak256 Hasher, and for ETH units use Eth Unit Converter.

Use the Hex ↔ Decimal tool to convert hex and uint256.