Amps, volts, and watts decide whether your actuator system gets enough power or cooks the wiring. Voltage is electrical pressure. Amps are current flow. Watts are power. For DC actuator systems, the first sizing check is simple: watts = volts × amps.
Measure the hard part of travel, not the easy middle. Size the supply for loaded current and startup spikes, not the quiet middle of free travel.
"The power supply has to survive the worst case, not the easy middle. Free-running current looks tidy on a spec sheet, but the loaded actuator and the startup spike are what trip undersized supplies." — Robbie Dickson, Founder and Chief Engineer of FIRGELLI Automations
What are amps, volts, and watts?
<<Amps, volts, and watts decide whether your actuator system gets enough power or cooks the wiring. Voltage is electrical pressure. Amps are current flow. Watts are power. For DC actuator systems, the first sizing check is simple: watts = volts × amps.
Measure the hard part of travel, not the easy middle. Size the supply for loaded current and startup spikes, not the quiet middle of free travel.
"The power supply has to survive the worst case, not the easy middle. Free-running current looks tidy on a spec sheet, but the loaded actuator and the startup spike are what trip undersized supplies." — Robbie Dickson, Founder and Chief Engineer of FIRGELLI Automations
What are amps, volts, and watts?
Volts push current through the circuit. Amps measure how much current flows. Watts measure electrical power.
What is the simple explanation?
A 12V actuator pulling 10A uses 120W while it runs. If the load increases and current rises, power rises too.
Use the formula below to calculate actuator power.
Watts = volts × amps
What should the calculator inputs be?
Use this as a first-pass sizing tool. Then confirm the final choice against the actual FIRGELLI product page, the wiring diagram, and your real mounting geometry.
How do you use this calculator?
- Enter the real project values, not guesses from a different mechanism.
- Use measured current, load, stroke, voltage, or signal values where you can.
- Add margin for real brackets, wiring, friction, and installation conditions.
- Click Calculate to see your result.
How should you size actuator power?
Match voltage first. A 12V actuator needs a 12V DC supply. Then size current for the highest current the system may see, especially if multiple actuators run together.
Do not size the power supply from free-running current only. A loaded actuator pulls more current, and startup current can jump above normal running current.
What is a simple example?
2 actuators each pull 8A on a 12V system. Total current = 8 × 2 = 16A.
Watts = 12 × 16 = 192W. With 1.25x margin, power supply target = 20A, or 240W.
Recommended FIRGELLI setup
Which FIRGELLI products fit this job?
Choose power supplies from voltage, total current, margin, and installation environment.
AC to DC Power Supply 12V 30A
Use this when the project plugs into wall power and needs a 12V DC supply with high current capacity.
View 12V 30A Power Supply
Water Resistant 12V 30A Power Supply
Use this when the power supply location needs a water-resistant 12V 30A option.
View Water Resistant Supply
DC Power Adaptor 12V
Use this for smaller 12V actuator projects where the current demand fits the adaptor rating.
View DC Power AdaptorFor controls, match the current rating of the switches, relays, or motor driver to the actuator system.
What are common mistakes when using this calculator?
- Entering free-running current instead of loaded current. The actuator pulls more current under real load — use measured or rated current under the application load, not the unloaded number on the spec sheet.
- Forgetting to multiply by the number of actuators running simultaneously. If two actuators run together at 8A each on a 12V system, the supply must handle 16A, not 8A.
- Skipping the margin factor. Startup current and brief load spikes can exceed steady-state current — 1.25x to 1.5x margin protects the supply from nuisance trips and thermal stress.
- Ignoring voltage drop in long wire runs. The calculator sizes the supply, but undersized or long wiring drops voltage at the actuator under load. The supply current rating alone will not fix wiring losses.
- Mixing voltage ratings. A 24V actuator on a 12V supply will not produce rated force or speed — match voltage first, then size current.
How can you verify the calculator output is reasonable?
- Cross-check the current input against the actuator product page. Use the rated current under load — not free-running current.
- Measure actual current draw after installation. Use a clamp meter while the actuator runs under real load and compare to the calculator estimate.
- Run the system through a full cycle and check the power supply temperature. A correctly sized supply runs warm, not hot. A supply that gets hot under steady operation is undersized.
- Confirm the supply voltage at the actuator terminals under load. If it sags well below rated voltage, wiring is undersized and the supply current rating alone will not fix it.
- For multi-actuator systems, verify the supply holds voltage when all actuators start together. Simultaneous startup is the worst case for current demand.
