How to think about payback, why an older machine earns less, and what owners look at before replacing or adding machines.
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Every owner asks the same two questions: when will my machine have paid for itself, and how long will it keep earning. Neither has a fixed answer, because both depend on things nobody controls. What you can do is read your own figures correctly and know what moves them.
Payback is the point where what a machine has mined, after hosting, adds up to what you paid for it. It compares two things:
Payback is a record of the past. A projected payback, in months or years, is an estimate built on today's conditions, and conditions change.
Your portal values the bitcoin earned at the price on the day it was earned. That is one honest way to count. An owner who kept the bitcoin can also ask a second question: how much bitcoin do I now hold, and what did each one cost me to produce? The card Your cost per bitcoin on My miners answers that. The two views can tell different stories in the same month. Decide which one matches what you are doing with the bitcoin.
| What moves | Effect on payback |
|---|---|
| Bitcoin price | A higher price shortens it in dollar terms. A lower price lengthens it. |
| Network difficulty | Rising difficulty means less bitcoin per TH/s, so it lengthens. |
| Halving | The bitcoin mined per day drops at each one. |
| Uptime | Every hour off is an hour that mines nothing. |
| Electricity rate | A lower rate leaves more of what is mined. |
A machine does not slow down much with age. The network speeds up around it. As newer machines join, difficulty rises, and the same TH/s earns less bitcoin than the year before. The machine's electricity need stays the same, so the part left after hosting gets thinner.
Parts also wear. Fans, power supplies and hash boards are replaced over a machine's life, and each repair is time off. A well-kept machine can run for many years. Whether it is still worth running is a different question from whether it still works.
A machine is worth running for as long as what it mines is worth more than the electricity it uses. Two things stretch that period: a low J/TH, and a low electricity rate. That is why an older machine is often still worth running at a site with cheap power long after it would have been switched off elsewhere. See Hashrate, efficiency and uptime.
Good to know: Nobody knows the price of bitcoin or the difficulty a year from now. Any payback figure that looks certain is leaving something out.
Careful: Mining output depends on bitcoin's price, network difficulty and uptime, and is not guaranteed. Nothing here is investment advice.