# Bitcoin transaction input

## Definition

A Bitcoin transaction input references a previous unspent output and provides the data needed to satisfy that output's spending conditions.

## What it means in practice

A transaction can contain multiple inputs, which can increase its data size and therefore influence the total fee at a given fee rate.

## How this concept appears in Terenval Wallet

When Terenval spends BTC, the wallet selects spendable Bitcoin outputs and constructs the necessary transaction inputs on the user's behalf.

**Important:** Input count can affect fees even when the amount sent is small, especially for wallets with many small UTXOs.

**[Install Terenval Wallet](https://wallet.terenval.com/?lang=en)**

## Related terms

- [UTXO](https://wallet.terenval.com/glossary/utxo/)
- [Bitcoin transaction output](https://wallet.terenval.com/glossary/bitcoin-transaction-output/)
- [Bitcoin transaction](https://wallet.terenval.com/glossary/bitcoin-transaction/)
- [Bitcoin fee rate](https://wallet.terenval.com/glossary/bitcoin-fee-rate/)
- [Bitcoin Script](https://wallet.terenval.com/glossary/bitcoin-script/)

## Related Terenval Answers

- [What Is a Crypto Wallet and What Does It Actually Store?](https://wallet.terenval.com/answers/what-is-a-crypto-wallet-and-what-does-it-store/)
- [How to Send Crypto Safely Between Wallets](https://wallet.terenval.com/answers/how-to-send-crypto-safely-between-wallets/)
- [Can the Same Seed Phrase Restore Bitcoin and Ethereum Accounts?](https://wallet.terenval.com/answers/can-same-seed-restore-bitcoin-and-ethereum/)

## Sources and review

- [Bitcoin Developer Guide](https://developer.bitcoin.org/devguide/)
- [Bitcoin Improvement Proposals](https://github.com/bitcoin/bips)
- [Terenval supported networks](https://wallet.terenval.com/info/supported-networks/)

Published by Terenval. Last reviewed: 2026-10-02. Terenval product statements are first-party information.

Official page: https://wallet.terenval.com/glossary/bitcoin-transaction-input/