Watt Meter
A watt meter shows the actual draw from the outlet. The spec sheet and the calculators give you an expectation, the power bill arrives based on facts.
Why measure when there is a spec sheet
The spec sheet figure was taken at the factory under reference conditions. Your ASIC draws differently: another firmware profile, another temperature, an aging power supply, sagging line voltage. A gap of a few percent is normal, and a few percent of three kilowatts around the clock is real money over a year.
For a single miner a plug-in watt meter is enough, with one caveat: household models are rated for 16 A, which is about 3.6 kW. A modern ASIC comes right up against that limit, so the meter needs an honest rating, not a marketplace souvenir.
A rack is measured with clamp meters on each phase, or you read the PDU counter. Clamps also reveal phase imbalance, and a smart PDU keeps history: for a fleet that beats walking around with a meter.
Measure a warmed-up miner, half an hour after startup, and take the average over an hour rather than an instant reading: consumption breathes along with autotune and the fans.
The short version
| Single miner | a plug-in watt meter with an honest 16 A rating |
| A rack | clamp meters or the PDU counter |
| When to measure | a warmed-up miner, an hour's average |
| Normal gap from spec | a few percent |
| What to fix at a big gap | voltage, the power supply, dust |
How to measure usefully
Record the figure on a warmed-up miner in every firmware profile: your own consumption profile instead of the spec sheet's.
Recalculate J/TH from actual watts and the pool's actual hashrate: that is the honest efficiency of your ASIC.
Repeat the measurement after cleaning, repasting, and firmware changes: that is how you see what the work gave you.
Investigate a sharp rise in consumption at the same hashrate: dust, a degrading power supply, sagging line voltage.
An example in numbers
The spec sheet says the ASIC draws 3250 W. On a warmed-up miner the watt meter shows 3390: a hot room, fans running high, a power supply three years old. The 140 W difference turns into about 100 kWh a month, and a payback calculated from the spec sheet lies by exactly that money.
Related terms
- Power Consumption
- Kilowatt Hour
- PSU Efficiency
- Efficiency, J/TH
- Circuit Breaker and RCD
- Three Phase Power
Where to go next on the site
Numbers
Hardware
- ASIC Miner knowledge base
Questions and answers
Why is the real draw above the spec
The spec was measured under reference conditions. Heat, dust, an aging power supply, and voltage sag all add watts, and every ASIC adds its own.
Will a cheap plug-in watt meter do
For a miner near the 16 A limit, better not: cheap meters lie at high currents and heat up themselves. Either an honest meter or clamps.
How often should I remeasure
After every intervention, a cleaning, repasting, a firmware change, and simply once a season: rising consumption is an early symptom of degradation.
How the terms connect
Every link in the chain is clickable. Orange marks where you are now.
Looking for an ASIC miner
The catalog holds 212 models. You can compare them by hashrate and by joules per terahash, then plug your own rate into the calculator and see what stays in your pocket.
Page written and checked by Denys Klimchuk. Updated .