Antminer S21 vs S19: Complete Comparison 2025
Detailed head-to-head comparison of Bitmain's flagship Bitcoin miners. We analyze specs, profitability with South African electricity costs, and provide clear buying recommendations.
Quick Verdict
For most South African miners, the Antminer S21 is the better choice despite its higher upfront cost. Its superior efficiency (17.5 J/TH vs 29.5 J/TH) means significantly lower electricity bills, faster ROI, and better profitability with Eskom rates. The S19 only makes sense if you have very cheap electricity or are buying second-hand at a steep discount.
Specifications Comparison
| Specification | Antminer S21 | Antminer S19 | Winner |
|---|---|---|---|
| Hashrate | 300 TH/s | 512 TH/s | S21 |
| Power Consumption | 4050W | 10600W | Similar |
| Efficiency | 13.5 J/TH | 20.7 J/TH | S21 |
| Price (ZAR) | R94,199.00 | R277,299.00 | Varies |
| Availability | ✓ In Stock | ✓ In Stock | - |
Profitability with South African Electricity
Based on Eskom average rate of 147.50 c/kWh and Bitcoin at R1,483,664.00 ZAR:
Antminer S21
- Daily Revenue:
- R124.36
- Daily Electricity Cost:
- - R143.37
- Daily Profit:
- R-19.01
- Monthly Profit:
- R-570.32
Antminer S19
- Daily Revenue:
- R212.24
- Daily Electricity Cost:
- - R375.24
- Daily Profit:
- R-163.00
- Monthly Profit:
- R-4,890.00
Profitability Disclaimer: These calculations use real-time Bitcoin prices from CoinGecko (R1,483,664.00) combined with estimated network difficulty and Eskom electricity rates. Actual profitability varies significantly with Bitcoin price fluctuations, network difficulty changes, and your specific electricity costs. Mining rewards decrease over time due to halving events and increasing competition. View current crypto prices or calculate your own ROI before purchasing.
Buying Recommendations
Choose S21 if:
- ✓You're paying standard Eskom rates (140-150 c/kWh)
- ✓You want maximum efficiency and lowest operating costs
- ✓You're using solar power (better ROI with lower power draw)
- ✓You want the latest technology and longest useful life
Choose S19 if:
- ✓You have access to very cheap electricity (<100 c/kWh)
- ✓You can buy second-hand at a significant discount
- ✓Your budget is strictly limited
- ✓You're comfortable with slightly lower efficiency
Frequently Asked Questions
Which is more efficient: Antminer S21 or S19?
The Antminer S21 is significantly more efficient at 17.5 J/TH compared to the S19 at 29.5 J/TH. This means the S21 uses about 40% less electricity per unit of hashrate, making it more profitable with South African electricity costs.
Is the Antminer S21 worth the higher price over the S19?
Yes, in South Africa the S21 typically pays for itself faster due to lower electricity consumption. With Eskom rates averaging 147.50 c/kWh, the S21's superior efficiency (17.5 J/TH vs 29.5 J/TH) results in significantly lower daily operating costs.
Which Antminer is better for solar mining?
The Antminer S21 is better for solar mining because its 3250W power consumption is more manageable with typical residential solar systems. The S19 at 3250W draws similar power but produces less hashrate, making the S21 more efficient for solar setups.
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