An older ASIC can still cover its electricity bill without being your best option. A new machine may be much more efficient, yet buying it might not beat simply selling your existing equipment. Your decision therefore needs more than a payback estimate or a reminder of how much the original hardware cost.
A useful comparison tracks money from today onward: what you will receive, what you still need to pay, and what you might recover by selling the equipment. You can reproduce the following method in an ordinary spreadsheet. The figures are illustrative, not current hardware offers or forecasts of mining returns.
Three options instead of one payback calculator
Compare three choices: keep running your current ASIC, sell it and buy a replacement, or sell it and stop mining. Use the same time horizon, such as twelve months, and consistent assumptions about bitcoin prices and electricity costs. Otherwise, you are comparing different forecasts rather than different machines.
Financial tools can help organize scenarios. For example, https://www.numevia.io/ presents a service advertising cash flow and expense forecasting alongside financial reporting. That is not the same as a dedicated mining calculator: these claims do not establish ASIC support, mining-pool connections, or verified mining payback calculations.
The product’s limitations also matter. NUMEVIA’s terms describe the current build as a front-end demo and state that outputs are not financial advice. Your decision therefore needs a model you can check yourself, rather than confidence in a convincingly worded AI answer.
Which costs matter, and why the original ASIC price is a sunk cost
Today’s decision cannot change the historical purchase price. If you once paid CZK 100,000 for the machine, that amount alone is not a reason to keep operating it. Its current net resale value does matter: keeping the machine means giving up the opportunity to collect that money now. Record the sale proceeds in whichever option actually includes the sale; do not count them again as an additional cost.
Accounting depreciation is not a monthly payment from your bank account either. It matters for accounting and potentially for tax, but it should not replace the actual hardware payment in your cash flow model. Assess tax consequences separately under your own circumstances. The example below is before tax and excludes financing; VAT-registered operators should treat recoverable VAT and tax consistently across all options.
For electricity, identify which charges would actually change when operations change. The Czech Energy Regulatory Office’s guidance, Jak se zorientovat v řádném vyúčtování za elektřinu, distinguishes consumption-based charges, fixed supplier charges, and charges for reserved capacity or the main circuit breaker. Switching off one ASIC may not eliminate your household’s entire monthly bill. Dividing the whole bill by consumption can therefore misrepresent the savings.
Use the cost of each additional kWh, including applicable consumption-based charges. Include savings from changing the main breaker or closing a separate electricity connection only if you will actually make those changes. Add ventilation, repairs, shipping, and any electrical installation work. Value recovered heat only against heating costs it genuinely replaces, not as an automatic year-round bonus.
Worked example: keep, replace, or sell the machine
Use a twelve-month horizon and, for simplicity, 720 hours per month. The old ASIC draws 3 kW and the new one 2 kW. Both mine for 95% of the time and, in this simplified example, consume no electricity during downtime. Electricity costs CZK 4/kWh. The power figures cover the machines; additional ventilation is excluded. In your actual spreadsheet, use measured power consumption and real calendar hours.
Assume monthly revenue before fees at uninterrupted operation of CZK 12,000 for the old machine and CZK 16,000 for the new one. These figures value mined BTC at an assumed selling price; they are not guaranteed receipts. Allow a combined 2% deduction for pool fees and selling costs. Monthly maintenance cash outflows are CZK 600 for the old machine and CZK 400 for the new one, although actual repairs will be irregular.
- Old ASIC: receipts after downtime and fees = 12,000 × 0.95 × 0.98 = CZK 11,172. Electricity = 3 × 720 × 0.95 × 4 = CZK 8,208. Net monthly operating cash flow = 11,172 − 8,208 − 600 = CZK 2,364.
- New ASIC: receipts = 16,000 × 0.95 × 0.98 = CZK 14,896. Electricity = 2 × 720 × 0.95 × 4 = CZK 5,472. Net monthly operating cash flow = 14,896 − 5,472 − 400 = CZK 9,024.
You can sell the old machine today for net proceeds of CZK 18,000. The new machine costs CZK 90,000, plus CZK 6,000 for installation. At the end of the horizon, assume net resale values of CZK 6,000 for the old machine and CZK 40,000 for the new one. For clarity, this calculation does not discount future amounts and assumes an immediate sale at the end of the period.
- Keep: 12 × 2,364 + 6,000 = CZK 34,368.
- Replace: 18,000 − 90,000 − 6,000 + 12 × 9,024 + 40,000 = CZK 70,288.
- Stop: selling immediately brings in CZK 18,000, with no further mining receipts or expenses.
In the base scenario, replacement beats keeping the old machine by CZK 35,920. However, that result includes the assumed final sale; it is not all cash generated during operation. The increase in monthly operating cash flow is CZK 6,660, against an initial net replacement outlay of CZK 78,000. Simple incremental payback, excluding the final sale, is approximately 11.7 months.
Give each month its own spreadsheet column and separate the initial purchase, operations, and final sale. For a longer horizon or a significant cost of capital, calculate net present value: divide each future cash flow in month t by (1 + monthly discount rate) raised to the power t. Use the same rate for all options; do not compare one option’s discounted result with another’s undiscounted total.
Stress scenarios: price, mining difficulty, electricity, and downtime
Today’s revenue in Czech crowns is not a constant for the machine’s entire life. The Bitcoin Developer Reference – Block Chain explains the proof-of-work target, difficulty, and the block subsidy halving every 210,000 blocks. It also distinguishes the subsidy from transaction fees. Historical subsidy figures in that documentation should not be mistaken for the network’s current subsidy.
Separate the quantity of BTC earned from its value in crowns. Hardware performance, network competition, availability, and pool rules affect the amount earned. The BTC price and currency exchange rate then determine its local-currency value. If a calculator already includes pool fees or downtime, do not deduct them again. If you hold the coins, distinguish their estimated value from cash available to pay electricity bills.
What happens if revenue in crowns before fees falls by 30% for the entire year? With all other assumptions unchanged, monthly cash flow falls to −CZK 987.60 for the old machine and CZK 4,555.20 for the new one. Including resale values, the twelve-month totals become −CZK 5,851.20 for keeping the old machine and CZK 16,662.40 for replacement. Selling immediately for CZK 18,000 beats both operating options in this scenario.
Resale values have deliberately been left unchanged to isolate the revenue effect. In reality, weaker mining economics can also depress used ASIC prices. Test lower revenue, higher electricity costs, longer downtime, and weaker resale values together. Repairs may not reduce every expense in proportion to lost mining time. Alongside the overall result, monitor the lowest projected cash balance: a positive expected return will not pay a bill if you run out of money first.
How to update the model and what to check before automation
Start with a manual weekly record and a monthly review. Keep actual pool payouts in BTC, measured electricity consumption, repair costs, and realized selling prices. Give each estimate a date and a source. Differences between forecast and actual results will then show whether the issue came from machine availability, consumption, coins earned, or their selling price.
Automation makes sense only after those inputs have been checked. On its company profile page, O společnosti NUMEVIA, NUMEVIA describes an API for integrating its AI functionality into products, services, and internal systems. This is a general integration claim, not evidence of available connectors for mining pools, ASICs, or cryptocurrency exchanges.
Before using any API, verify documentation availability, access conditions, limits, and behavior during outages. Check time zones, timestamps, currencies, and units: W are not kW, TH/s are not GH/s, and a pool payout may not represent earnings for the same calendar day. An import should flag duplicates and missing periods rather than silently replace them with zero.
Keep calculations traceable through spreadsheet formulas and check automated summaries against original statements. Use the minimum permissions needed to read data, ideally read-only access. An analytical tool does not need your wallet seed phrase or permission to withdraw funds from an exchange.
A decision checklist before buying a new ASIC
Before ordering, verify actual power consumption, electrical requirements, noise, cooling, warranty, and delivery timing. An asking price for your old machine is not a confirmed sale price; deduct shipping, fees, and any negotiated discount. Be equally conservative about the new machine’s value a year from now. If replacement wins only because of an optimistic final sale, the conclusion is fragile.
Replacement makes economic sense when its future net cash flows, at an acceptable level of risk, beat both keeping the old machine and stopping mining. Set a threshold for reducing or stopping operation and a date for the next review. You cannot recover the original purchase price by generating further losses; a sound decision protects the money you can still influence today.