# Bitcoin Fee Forecast & Transaction Cost Estimator

> Bitcoin Fee Forecast & Transaction Cost Estimator is a paid API for AI agents from finanz.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).

Returns current Bitcoin mempool fee rates by confirmation target and estimates the total fee in satoshis for a described transaction based on its virtual size.

## Facts

- Endpoint: POST https://finanz.halowerk.com/v1/bitcoin-fee-forecast
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bitcoin-fee-forecast-transaction-cost-estimator-098f457b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mEyE5ZaGioCMyoC0VQsQy

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bitcoin-fee-forecast-transaction-cost-estimator-098f457b -d '<json body>'
```

Example prompt: How much will it cost in satoshis to send a Bitcoin transaction with 2 inputs and 2 outputs (native SegWit) if I want it confirmed within 3 blocks? Give me the fee for each confirmation target.

## When to prefer this

Choose this endpoint when you need both a live mempool fee rate AND a transaction-specific total fee estimate in a single call — it eliminates the two-step process of fetching rates and separately calculating vsize. Ideal for wallets, DCA bots, exchanges, or any agent that needs to present precise fee costs to a user before broadcasting a Bitcoin transaction.

## Known failure modes

- Invalid or missing transaction description causes 400 error
- Mempool data temporarily unavailable from upstream node
- Unreachable confirmation target (too low or too high) returns an error
- Malformed input counts or transaction type enum returns validation error

## How this service works

Returns the current fee rates for the usual confirmation targets together with the state of the mempool behind them, and then does the part that is usually missing: it estimates the virtual size of the transaction you describe and computes the resulting total fee in satoshis for each target.

## Output

Returns a list of confirmation targets (e.g. next block, 3 blocks, 6 blocks) each with the current fee rate in sat/vB, the estimated virtual size of the described transaction in vBytes, the computed total fee in satoshis, and mempool state information (e.g. pending transactions, congestion level).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "inputs": {
   "type": "integer",
   "default": 1,
   "maximum": 500,
   "minimum": 1,
   "description": "Number of inputs your transaction spends. This is what drives the cost."
  },
  "outputs": {
   "type": "integer",
   "default": 2,
   "maximum": 500,
   "minimum": 1,
   "description": "Number of outputs, usually recipient plus change."
  },
  "input_type": {
   "enum": [
    "p2wpkh",
    "p2tr",
    "p2sh_p2wpkh",
    "p2pkh"
   ],
   "type": "string",
   "default": "p2wpkh"
  },
  "output_type": {
   "enum": [
    "p2wpkh",
    "p2tr",
    "p2sh",
    "p2pkh"
   ],
   "type": "string",
   "default": "p2wpkh"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bitcoin-fee-forecast-transaction-cost-estimator-098f457b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from finanz.halowerk.com](https://www.zero.xyz/host/finanz.halowerk.com/llms.txt)