Machine-shop electricity cost calculator
Estimate a machine shop's monthly electricity cost by separating production equipment, compressed air, facility baseload, operating hours, and the billed peak.
Machine-shop electricity cost calculator
Separate production equipment, compressed air, and the shop baseload to build a transparent monthly electricity estimate.
A small shop operating 220 hours per month
A shop with 125 kW of connected production equipment at 55% utilization, a 30 kW air compressor at 70% utilization, and 12 kW of lighting and baseload averages about 101.8 kWduring the modeled schedule. Across 220 hours, that is approximately 22,385 kWh. At $0.12/kWh with a 118 kW billed peak at $18/kW, the illustrative monthly energy and demand cost is $4,810 before fixed charges, taxes, and riders.
Connected load is not the same as consumed energy
A machine nameplate describes rated conditions. Actual input changes with the process, tool engagement, spindle speed, motor loading, auxiliary systems, warmup, idle modes, and controls. Summing every nameplate and multiplying by shift hours will usually overstate energy if equipment does not run fully loaded together.
Begin with the calculator's utilization factors, then replace them with measured values. Portable power logging, equipment controller data, submeters, or interval panel data can distinguish productive operation from ready, idle, and off-shift consumption.
Build the shop estimate by system
| System | Energy driver | Useful measurement |
|---|---|---|
| CNC and production | Cycle time, cutting load, idle time, auxiliaries | kWh per operating hour or production unit |
| Compressed air | Pressure, leaks, controls, storage, end uses | Compressor kW, loaded hours, and off-shift cycling |
| Coolant and extraction | Runtime and control sequence | kW during production versus idle |
| HVAC and ventilation | Weather, heat gains, exhaust, and makeup air | Seasonal interval profile |
| Lighting and office | Area, schedule, and controls | Off-shift baseload |
Compressed air deserves its own review
The Department of Energy provides tools and guidance for analyzing compressed-air systems, storage, controls, air quality, leaks, and inappropriate uses. A useful first check is to observe the compressor during a nonproduction period. Repeated loaded operation may indicate leaks or loads that could be isolated, but any pressure or control change should be reviewed against production needs.
- Trend compressor power and pressure through an entire shift.
- Measure off-shift cycling after production loads are isolated.
- Check whether system pressure exceeds end-use requirements.
- Identify open blowing and other inappropriate compressed-air uses.
- Compare machine startup schedules with the facility demand peak.
Frequently asked questions
How much electricity does a machine shop use?
There is no reliable single value for all shops. Equipment mix, spindle and motor size, cutting time, idle time, shifts, compressed air, coolant systems, ventilation, HVAC, and production volume all affect monthly kWh and peak demand.
Should connected machine kW be treated as average load?
No. Nameplate or connected kW represents capacity, not continuous consumption. This calculator applies a utilization factor for screening, but measured equipment or panel data is preferable.
Why separate compressed air from production machines?
Compressed air may continue running during machine idle periods and can be affected by leaks, pressure, controls, storage, and inappropriate end uses. Separating it makes the estimate easier to verify and improve.
Does a lower monthly kWh guarantee a lower demand charge?
No. Demand is based on the highest qualifying interval under the tariff. A short overlap of machines, compressors, HVAC, or startup loads can preserve the same billed peak even if total energy falls.