The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
A unspent transaction output (UTXO) is a Bitcoin transaction output that has not been used as an input in a later transaction. It holds a specific amount of satoshis under conditions that must be met to spend it.
How a UTXO is created and spent
Bitcoin transactions use existing outputs as inputs and create new outputs. An input points to an earlier output; the new transaction assigns its value to one or more outputs and pays any transaction fee. An output remains a UTXO until a later transaction spends it. The Bitcoin Developer Guide’s transaction overview explains this flow.
For example, if your wallet uses an output worth more than the amount you want to send, the transaction can create an output for the recipient and a change output returning the surplus to you, less the fee. That change is not a special kind of coin: it is another transaction output, and it can remain unspent until used later.
How UTXOs relate to a wallet balance
A wallet does not contain a single Bitcoin balance entry on the blockchain. Its displayed spendable balance is an aggregate of the satoshis in the UTXOs the wallet can spend. Those satoshis may be spread across several outputs. The developer guide illustrates this with a 10,000-satoshi balance; that figure is an example, not a network statistic.
#1 Best Overall
- BITCOIN EXCLUSIVE, PHONE VERIFICATION: Bitkey is designed from the ground up exclusively for bitcoin — a dedicated hardware wallet for secure bitcoin storage. Approve transactions with a tap using your phone and NFC. No device screen is required.
- SELF-CUSTODY, NO EXCHANGE OR CUSTODIAN REQUIRED: You hold two of the three keys in the Bitkey system – one on your phone and one on your Bitkey device. The third is stored on Bitkey’s server and cannot move your bitcoin on its own.
- NO SEED PHRASE: Set up and use Bitkey without creating or storing a seed phrase.
- 2-of-3 MULTISIG: Three keys are stored separately across your phone, Bitkey device, and Bitkey’s server. Any two keys are required to move your bitcoin.
- BUILT-IN RECOVERY: Encrypted backup and recovery tools can help you regain access if you lose your phone or Bitkey device. You can also designate a Recovery Contact.
UTXO versus transaction output and outpoint
Every UTXO is a transaction output, but not every output is a UTXO: an output stops being unspent once a later transaction consumes it. An output’s spending conditions are encoded in its pubkey script, so it is spendable only by someone who can satisfy those conditions.
An outpoint identifies a particular output by combining its transaction ID with that output’s index within the transaction. The outpoint is the identifier; the UTXO is the output that remains unspent. See the Bitcoin Developer Reference for transactions.
Rank #2
- Unparalleled Security: Protect your assets NDA-free EAL 6+ Secure Element, offering robust defense and complete transparency
- Simple & Secure Interface: Manage your digital assets easily with a clear OLED screen for secure on-device confirmations
- Supports 1000s of Coins & Tokens: Securely handle thousands of assets, including Bitcoin, Ethereum, and more, all in one wallet
- Effortless Asset Management: Monitor and transact seamlessly with Trezor Suite, our intuitive desktop and mobile app
- Enhanced Backup Solution: Rest assured with Multi-share Backup, eliminating single points of failure for secure cold wallet recovery
Why an output can be spent only once
A transaction output can be used as an input only once. Trying to spend it again is a double spend. Full nodes track currently unspent outputs in the UTXO set and use it to check whether an input refers to an output that is still available. BIP 64 describes the UTXO set as a database used to check the status of referenced outpoints.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Special case: newly mined coinbase outputs
Bitcoin outputs created by a coinbase transaction—the transaction that claims a block’s subsidy and fees—cannot be spent until they have matured. The Bitcoin Developer Guide specifies a 100-block maturity condition for coinbase outputs in its block-chain guide. This delay is a spending restriction; it does not change what a UTXO is.
Quick Recap
Best Value
- Effortlessly build your crypto portfolio via the all in one Ledger Wallet app: buy, sell, send, receive, swap, stake and more across popular blockchains. 15,000+ coins & tokens in a single dashboard. Keep a close eye on the market. Compare service providers. Track performance. Get timely alerts. Build your portfolio with confidence.
- Effortlessly build your crypto portfolio via the all in one Ledger Wallet app: buy, sell, send, receive, swap, stake and more across popular blockchains. 15,000+ coins & tokens in a single dashboard. Keep a close eye on the market. Compare service providers. Track performance. Get timely alerts. Build your portfolio with confidence.
- Enjoy Bluetooth connectivity, iOS access, and hours of battery use with this mobile-first, secure backup signer. Freedom you can depend on.
- Genuine Check: confirm your signer is authentic during setup with the Ledger Wallet app.
- Protect your signer: keep it in mint condition at all times with a bespoke Pod or Case to avoid scratches and everyday wear and tear.
Rank #4
- Dual-chip architecture for maximum protection: The next-gen, fully auditable TROPIC01 chip works alongside a certified EAL6+ Secure Element—completely NDA-free—to deliver radically transparent, industry-leading defense against physical attacks.
- Quantum-ready security: Get protection against future threats with the first-ever hardware wallet designed with quantum-ready architecture.
- See every detail with confidence: Our largest high-resolution color touchscreen makes it easy to navigate your assets, review transactions and manage your coins with clarity.
- Wireless freedom with encrypted Bluetooth control: Manage, buy, swap and stake securely using Trezor Suite on desktop or mobile. Qi2-compatible wireless charging keeps your Trezor powered up. No cables required—security meets convenience.
- Works seamlessly with Android, iOS and desktop: Connect wirelessly or via USB-C to your phone or computer. Manage your crypto anywhere with our companion Trezor Suite app.
Rank #3
- Unparalleled Security: Protect your assets with EAL 6+ Secure Element, offering robust defense and complete transparency
- Simple & Secure Interface: Manage your digital assets easily with a clear OLED screen for secure on-device confirmations
- Supports 1000s of Coins & Tokens: Securely handle thousands of assets, including Bitcoin, Ethereum, and more, all in one wallet
- Effortless Asset Management: Monitor and transact seamlessly with Trezor Suite, our intuitive desktop and mobile app
- Enhanced Backup Solution: Multi-share Backup eliminates single points of failure for secure cold wallet recovery
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
