SMPS Size Calculator

Work out what size SMPS (power supply) your panel needs. Enter each load, choose 12 V, 24 V or 48 V and DIN rail or enclosed, and the calculator adds headroom and picks the lowest-priced in-stock genuine Mean Well models that fit, with today's price. Free, no sign-up.

How to use this calculator

List every device the supply will power: PLC, HMI, relay coils, sensors, solenoid valves, LED indicators. Use the current or wattage printed on each device or its datasheet. Pick the output voltage your devices need and how the supply will be mounted, then press Calculate.

How SMPS sizing works

An SMPS is rated in watts at its output voltage: a 24 V, 5 A unit is a 120 W supply. Add up the loads, add headroom for inrush and future additions, and choose the next size up. For mixed voltages, size a separate supply per voltage. See the Mean Well SMPS selection guide, the DIN rail SMPS wiring guide and the full Mean Well SMPS price list, or browse 24V SMPS, 12V SMPS and 48V SMPS.

SMPS calculator: frequently asked questions

How do I calculate what size SMPS I need?

Add up the power of every load on the supply (volts x amps, or the watts on the label, times the quantity), then add headroom on top. This calculator adds 25% by default, a common rule of thumb for continuous industrial loads; you can change it.

Why add headroom instead of matching the load exactly?

A power supply running at 100% all day runs hotter and has less margin for inrush current from relays, solenoids and motors. Headroom also leaves room to add a device to the panel later.

Should I choose a DIN rail or an enclosed SMPS?

DIN rail models (Mean Well MDR, HDR, EDR, NDR, TDR) clip onto the same rail as your MCBs and relays, which suits control panels. Enclosed models (LRS, RSP) are cheaper per watt and suit larger loads, LED signage and machines with space for a screw-mounted unit.

Can I run 12V devices from a 24V SMPS?

Not directly. Choose the SMPS output voltage that your devices need, or use a separate DC-DC converter. Mixing voltages on one supply damages the lower-voltage device.

Are these genuine Mean Well power supplies?

Yes. Voltkart is an authorised Mean Well distributor; every unit is supplied with a GST invoice from Delhi.