Antminer S21 vs S9: Which Bitcoin Miner Wins in 2025?
When it comes to Bitcoin mining, the process of using specialized hardware to validate transactions and earn new Bitcoin rewards. Also known as cryptocurrency mining, it's all about getting the most hash power for the least electricity cost. Two machines dominate the conversation: the Antminer S21, Bitmain's latest 2024 ASIC miner designed for maximum efficiency and the Antminer S9, a 2017 powerhouse that still runs in basements worldwide. This isn’t just about older vs newer—it’s about survival in a world where electricity prices and Bitcoin’s halving schedule make every watt count.
The Antminer S21 crushes the S9 in raw performance. It delivers 200 TH/s with a power draw of about 3,010 watts. That’s nearly 5 times the hash rate of the S9, which maxes out at 14 TH/s and pulls 1,320 watts. But here’s the catch: the S21 uses 15.05 joules per terahash, while the S9 uses 95 joules per terahash. That means the S9 wastes over 6 times more energy for the same work. If you’re paying $0.10 per kWh, the S21 pays for itself in months. The S9? It’s barely breaking even—and only if you have free power.
There’s also the matter of reliability. The S9 was built in 2017. Many units are now 7+ years old, running nonstop. Fans fail. Hashboards crack. Power supplies die. Even if you find a working S9, spare parts are scarce. The S21, by contrast, comes with a 1-year warranty, modern cooling, and firmware updates. It’s not just faster—it’s built to last.
But let’s be real: not everyone can afford a new S21. Some miners still use S9s because they bought them cheap during the 2021 crash, or they’re in regions with dirt-cheap electricity. Some even run them as hobby rigs. But if you’re starting fresh in 2025, buying an S9 is like buying a 2008 smartphone to stream 4K video. You can do it—but you’ll be frustrated, and you’ll pay more in electricity than you earn in Bitcoin.
What about mining pools? The mining pool, a group of miners who combine their hash power to increase payout frequency you join matters just as much as the machine. Whether you’re using an S21 or an S9, you need a stable pool like Foundry USA or F2Pool. The S21’s efficiency gives you more flexibility—you can profit even in high-fee pools. The S9? You need the lowest fees possible just to stay alive.
And don’t forget regulation. Countries like Kazakhstan and Norway are cracking down on energy-hungry miners. The S9’s inefficiency makes it a target. The S21? It’s the kind of machine regulators might allow because it’s far more energy-smart per unit of work.
Below, you’ll find real reviews, cost breakdowns, and long-term profitability charts for both machines. No fluff. Just numbers, real-world experiences, and what actually works today.
