Electrical Load Calculator in Excel: Current and Transformer Size

Before sizing a panel or a building supply you need the total load and the expected current. This sheet lists each load on one row, applies a demand factor, then calculates current, apparent power in kVA and a suggested transformer size with a safety margin.

What is inside the sheet?

• Ready load table (lighting, AC, sockets, heaters, pumps) with room for your own loads
• Individual demand factor per load
• Apparent power in kVA from the power factor
• Current for single-phase or three-phase systems
• Current with safety margin and a suggested transformer size

How to use it

1. Enter each load name, quantity and power in watts
2. Adjust the demand factor of each load for its usage
3. Enter power factor, voltage, number of phases and safety margin
4. Read the results at the bottom: kW, kVA, current and transformer size

Tips for best results

• Do not edit non-yellow cells so the formulas stay intact
• Keep a separate copy of the sheet for every project
• Use power values from the equipment nameplates

Frequently asked questions

What is a demand factor?

It is the share of the connected load expected to run at the same time. It reduces the calculated load.

Is it suitable for residential and commercial buildings?

Yes as an early estimation tool. Adjust the demand factors to the building type.

Download the sheet

Press the download button at the top of the page to get an Excel file ready to edit. The sheet is also available in Arabic from the language switcher.

Note: this sheet is for early estimates and day-to-day help. Have a qualified engineer verify results against the applicable code before construction.