Bitcoin Fee Estimation - Maximum Sats

About

Get real-time Bitcoin network fee estimates from mempool.space. Calculate satoshi costs for on-chain transactions based on desired confirmation target (blocks) or transaction size (vbytes).

Try It

5 sats via L402.

Target blocks Transaction vsize (bytes)

API Usage

# Get fee estimate for 3-block target with default 250vB transaction
curl -X POST https://maximumsats.com/api/fee-estimate \
  -H "Content-Type: application/json" \
  -d '{"target_blocks": 3}'

# Custom transaction size (e.g., a typical 2-input P2WPKH tx is ~250vB)
curl -X POST https://maximumsats.com/api/fee-estimate \
  -H "Content-Type: application/json" \
  -d '{"target_blocks": 6, "tx_vsize": 250}'

Sample Response

{
  "target_blocks": 3,
  "tx_vsize": 250,
  "selected_fee": {
    "sat_per_vbyte": 15,
    "target_blocks": 3,
    "estimated_satoshis": 3750,
    "estimated_sats": 3750,
    "label": "~3 blocks"
  },
  "all_estimates": {
    "fastest": { "sat_per_vbyte": 25, "target_blocks": 1, "estimated_satoshis": 6250 },
    "halfHour": { "sat_per_vbyte": 15, "target_blocks": 3, "estimated_satoshis": 3750 },
    "hour": { "sat_per_vbyte": 10, "target_blocks": 6, "estimated_satoshis": 2500 },
    "economy": { "sat_per_vbyte": 5, "target_blocks": 24, "estimated_satoshis": 1250 },
    "minimum": { "sat_per_vbyte": 1, "target_blocks": 144, "estimated_satoshis": 250 }
  },
  "source": "mempool.space",
  "timestamp": "2026-02-20T00:15:00.000Z"
}