Bitcoin UTXO and transaction planner

Model inputs, outputs, change and fee rates before you build a transaction. Nothing is signed, broadcast or linked to a wallet.

Build a transaction estimate

Enter the number and type of coins you plan to spend. The calculator estimates virtual size, then multiplies it by the chosen sat/vB fee rate.

InputsRecipient outputsInput typeFee rate (sat/vB) Include a change output

Estimated size—

Miner fee—

Fee in BTC—

Outputs created—

How fee rate changes this transaction

Hover the line to compare fee rates. The transaction shape stays fixed while the block-space bid changes.

UTXOs are the coins a transaction spends

A wallet balance is usually a set of unspent transaction outputs, or UTXOs. Spending three UTXOs generally needs three inputs, even when they belong to one wallet. More inputs mean more transaction data and usually a higher miner fee.

Change is a new coin

If selected inputs are worth more than the payment and fee, the wallet normally sends the remainder to a fresh change address. That change becomes another UTXO. Leaving change out does not make the remainder disappear: any unassigned value becomes miner fee.

Learn how this connects to Bitcoin transactions, then inspect current demand in the mempool explorer.

Planning choices and their trade-offs

Choice	Possible benefit	Risk or cost
Consolidate many UTXOs	Fewer future inputs	Larger transaction now; may reduce privacy
Use native SegWit	Lower virtual size	Recipient software must support it
Avoid tiny change	Prevents uneconomic outputs	Coin selection must be handled carefully
Wait for lower fees	May reduce cost	No guarantee demand will fall

This is a size model

Multisig scripts, inscriptions, unusual witness data and wallet coin selection can change the real size. Confirm the final transaction in trusted wallet software before signing.

How Bitcoin.now handles tool data

Calculated values

Deterministic tools state their assumptions beside the result. They do not present a model as an executable quote.

Observed values

External observations use read-only public data, retain the latest valid cache, and show freshness when a source is delayed.

Safety boundary

No tool trades, broadcasts, connects a wallet, stores a secret, or gives personal financial advice.

Review the data methodology, editorial policy, and risk disclaimer.

Using bitcoin utxo and transaction planner responsibly

Does the amount of bitcoin set the fee?

No. Transaction weight and the sat/vB bid set the miner fee. A large payment with one modern input can be smaller than a tiny payment that combines many old outputs.

When is consolidation useful?

Consolidation can reduce future input count when block space is inexpensive. It can also join coins that were previously separate, which may reveal information about common ownership.

Why can my wallet show another size?

Wallets know the exact scripts, signatures and coin selection. This planner uses conservative standard-size assumptions, so the signed transaction remains the final source of truth.