How do I calculate Transformer Sizing?

To calculate Transformer Sizing: Enter Total connected load, Demand factor, Average power factor and other values. Click Calculate. INDUGRID computes the result instantly using the formula: S_kVA = (sum P_loads x demand_factor) / (PF x eta_trafo). No registration required.

What units does the Transformer Sizing calculator use?

The Transformer Sizing calculator uses the following units: kW, %. SI units are used by default.

Is the Transformer Sizing calculator free?

Yes. The INDUGRID Transformer Sizing calculator is completely free, requires no account or login, and works on desktop and mobile browsers.

Electrical Engineering

Transformer Sizing

Calculate required transformer kVA rating based on connected loads, demand factor and efficiency.

Units:

in LinkedIn

💡Size transformers at 70-80% utilisation for thermal margin and future growth. Demand factor (simultaneity): not all loads run simultaneously. Typical industrial: 0.6-0.8. Inrush current on energisation: 8-12x rated current.

S_kVA = (sum P_loads x demand_factor) / (PF x eta_trafo)

Input

Total connected load iSum of all connected load nameplate powers in kW.

Demand factor iFraction of loads operating simultaneously. Offices: 0.5-0.7, Production: 0.6-0.85, Lighting: 0.9-1.0.

Average power factor iWeighted average power factor of all loads. Improve with PF correction capacitors.

Transformer efficiency iTransformer efficiency at full load. Distribution transformers: 97-99%.

Target utilisation iDesign utilisation of transformer. Recommended: 65-80%.

Result

Demand load [kW] —

Required transformer kVA [kVA] —

Recommended standard size [kVA] —

Full load current (400V) [A] —

Inrush current (x10) [A] —