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[172.104.61.193]) by gmr-mx.google.com with ESMTPS id 6a1803df08f44-8ceccba4d1asi3065706d6.2.2026.06.05.03.00.49 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Jun 2026 03:00:49 -0700 (PDT) Received-SPF: pass (google.com: domain of aj@erisian.com.au designates 172.104.61.193 as permitted sender) client-ip=172.104.61.193; Received: from aj@azure.erisian.com.au by cerulean.erisian.com.au with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wVRM3-0007VJ-1J for bitcoindev@googlegroups.com; Fri, 05 Jun 2026 20:00:46 +1000 Received: by email (sSMTP sendmail emulation); Fri, 05 Jun 2026 20:00:41 +1000 Date: Fri, 5 Jun 2026 20:00:41 +1000 From: Anthony Towns To: "bitcoindev@googlegroups.com" Subject: [bitcoindev] Testnet 4 difficulty/hashrate Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline X-Spam_score: -0.0 X-Spam_bar: / X-Original-Sender: aj@erisian.com.au X-Original-Authentication-Results: gmr-mx.google.com; spf=pass (google.com: domain of aj@erisian.com.au designates 172.104.61.193 as permitted sender) smtp.mailfrom=aj@erisian.com.au Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.8 (/) On Fri, Jun 05, 2026 at 07:35:27PM +1000, Anthony Towns wrote: > compared with current mainnet difficulty of ~138T, or testnet4's > current difficulty of ~1239M, If testnet4's current difficulty is D=1239M [0], and there were no min-difficulty blocks, that would be one thing. But there are min-difficulty blocks, and sufficient hashrate mining them with the clock set forward to saturate them. What's the actual hashrate for testnet4 given a reported difficulty D? [0] https://mempool.space/testnet4/block/000000000000000359f805aea2a5f18671bf98a1106d0cdbbfbe1f341f5e08dc?showDetails=true&view=actual#details Suppose the "correct" difficulty corresponding with actual hashrate would be H. Then real difficulty blocks are found every (D/H * 10 minutes) on average, and minimum time blocks fill up the rest of the retarget period. So between blocks 135072 and 137087, I see 192 real-difficulty blocks and 1824 min-difficulty blocks, suggesting that the real testnet4 difficulty should be H=130M. The limit on not having D/H=2016 is that with 2016 min-difficulty blocks, you'd have a retarget period taking up 4 weeks instead of 2 weeks. I think a real-difficulty block can reset up to 5 or 6 blocks of min-difficulty time (any more than that would violate median time constraints on behalf of the real difficulty block, or too-far-in-future constraints on the min-difficulty blocks), so I think that means that you want at least 1 real block for every 10 or 12 min-difficulty blocks, so a 192:1824 (1:9.5) ratio seems close to the max already. This also suggests ~90% of testnet4 blocks are being confirmed via competition in network propagation with only ~10% confirmed via PoW/hashrate competition. Cheers, aj -- You received this message because you are subscribed to the Google Groups "Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/aiKeSdrUDP8N1Xww%40erisian.com.au.