Should you send that Bitcoin transaction right now?
Live next-block, half-hour, hour, and economy fee rates from mempool.space, converted into sats and dollars for common transaction sizes. No account. No tracker cookies. AI agents: free /api/fees · paid L402 forecast /api/v1/forecast (21 sats) · llms.txt · agent docs.
| Transaction | vBytes | Next block | Economy | You save by waiting |
|---|
Custom size
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Fee Now is free. If a cheap-fee window saved you money, send a Lightning tip — any amount — to Hexbox Tools. No KYC, no signup.
Want a Nostr ping when fees drop below your target? Zap the announcement note 2,100 sats for 7 days of alerts, then reply below 5 (or any number). Default alert: fastest fee ≤ 3 sat/vB or ≥ 50. Announcement: announcement note.
How Bitcoin fees work
Bitcoin miners pick transactions by fee rate, measured in satoshis per virtual byte (sat/vB). A typical single-sig send is about 141 vBytes, so a 4 sat/vB rate costs 564 sats. When the mempool is busy, next-block rates jump; when it empties, economy rates can sit at 1 sat/vB.
Next-block is what you pay to aim for confirmation in the next block (~10 minutes on average). Economy is a low-priority rate that may take hours. If the gap between them is wide and your payment can wait, using economy is how you stop overpaying.
Fees often ease on weekends and during quieter UTC hours, and they spike when inscriptions, batch settlements, or sudden demand clog the mempool. This page rereads mempool.space recommended fees and USD price about every 30 seconds. Treat sizes as estimates — your wallet will show the exact vBytes for the transaction it builds.
JSON API (free, CORS open): /api/fees. Agents that pay Lightning: /api/v1/forecast (L402, 21 sats) — discovery at /llms.txt, /openapi.json, /api/agent.json.