Enter kVA and System Details
Use nameplate values when possible. For three phase systems, match the selected voltage basis.
Formula used
Direct current: I = (kVA × 1000) ÷ V
Single phase AC: I = (kVA × 1000) ÷ V
Three phase line to line: I = (kVA × 1000) ÷ (√3 × VLL)
Three phase line to neutral: I = (kVA × 1000) ÷ (3 × VLN)
Design current: Base amps × demand factor × (1 + safety margin ÷ 100)
How to use this calculator
- Enter the load name so exported results stay clear.
- Add the apparent power value in kVA.
- Enter the supply voltage from the equipment nameplate.
- Select direct current, single phase, or three phase.
- Choose the correct three phase voltage basis.
- Add power factor, efficiency, demand, and margin values.
- Press the calculate button and review the result above the form.
Example data table
| kVA | Voltage | System | Formula basis | Base amps |
|---|---|---|---|---|
| 10 | 230 V | Single phase | kVA × 1000 ÷ V | 43.48 A |
| 25 | 400 V | Three phase | kVA × 1000 ÷ √3 ÷ VLL | 36.08 A |
| 50 | 480 V | Three phase | kVA × 1000 ÷ √3 ÷ VLL | 60.14 A |
| 5 | 48 V | Direct current | kVA × 1000 ÷ V | 104.17 A |
Understanding kVA and Amps
kVA measures apparent power. Amps measure current flow. The two values are linked by voltage and phase type. A transformer, generator, inverter, or large appliance may show its size in kVA. A breaker, cable, or busbar usually needs amps. This calculator bridges that gap with clear inputs and direct current results.
Why Phase Type Matters
Single phase and direct current use a simple relationship. Apparent power equals voltage multiplied by current. Three phase systems share power across three conductors. That changes the divisor. The square root of three appears when line to line voltage is used. If line to neutral voltage is entered, the calculator uses the equivalent three phase form.
Using Voltage Correctly
Voltage is the most common source of error. Always choose the voltage that matches the equipment nameplate. A three phase panel may list 400 V line to line. The same system may have about 230 V line to neutral. Both describe the same supply. The selected basis tells the calculator which formula to apply.
Demand and Safety Margin
Real installations often need more than the raw current value. Demand factor can reduce the connected load when all devices do not run together. Safety margin can raise the design current for heat, starting, expansion, or uncertainty. These settings help planners compare base current with practical design current. They do not replace local electrical rules.
Power Factor and Efficiency
kVA does not include power factor. It describes the total apparent power drawn by the load. The calculator still lets you enter power factor. That value estimates real kilowatts. Efficiency then estimates useful output power. These extra values help when studying motors, transformers, generators, and energy costs.
Practical Design Notes
Current results should guide early sizing only. Cable size depends on insulation, temperature, conduit fill, distance, voltage drop, installation method, and code limits. Breaker selection also depends on load type and starting current. Motors may need special rules. Continuous loads may need additional allowance. Always verify final selections with a qualified person.
When This Tool Helps
Use this tool before buying a generator. Use it while checking transformer capacity. Use it when comparing single phase and three phase loads. It is also useful for estimating panel demand. Enter realistic voltage values. Then adjust demand and margin. Review both base amps and design amps before making decisions.
Reading the Result
Base amps show the electrical current from kVA alone. Adjusted amps include demand and margin. Current per run divides adjusted current across parallel conductors. Suggested breaker size is only a convenience value. It uses common ratings and rounds upward. It may not match every standard in every country. The result also shows kilowatts, useful kilowatts, and calculated voltages. These fields make checks easier. They also help users spot mismatched inputs before costly mistakes happen. Keep nameplate data nearby during every check. Small voltage changes often matter.
FAQs
What does kVA mean?
kVA means kilovolt-ampere. It measures apparent power. It combines real power and reactive power in AC systems. For conversion to amps, voltage and phase type are essential.
Is kVA the same as kW?
No. kVA is apparent power. kW is real working power. They become equal only when power factor equals one. Most AC loads have a lower power factor.
Why does three phase use √3?
Three phase line to line voltage relates to phase voltage through the square root of three. The formula uses that relationship to calculate line current correctly.
Should I use line to line or line to neutral voltage?
Use the value printed on the equipment nameplate. For most three phase equipment, line to line voltage is used. For phase to neutral loads, choose line to neutral.
Does power factor change the amp result?
For a kVA to amps conversion, power factor does not change apparent current. It is used here to estimate real kilowatts and useful output power.
What is demand factor?
Demand factor represents the portion of connected load expected to operate at once. A lower factor reduces the adjusted current. Use conservative values for critical circuits.
What does safety margin do?
Safety margin increases the base or demand-adjusted current. It helps account for heat, future expansion, voltage tolerance, and uncertainty during early planning.
Can this calculator size wires?
It gives current values that help with early sizing. It does not replace code tables, voltage drop checks, installation limits, or professional electrical design.
Why is the breaker only suggested?
The breaker value rounds upward to common ratings. Real breaker selection depends on rules, cable size, load type, ambient temperature, and starting current.
Can I use this for generators?
Yes. Enter the generator kVA rating and voltage. Select the correct phase type. Compare base current with design current before choosing cables or protection.
Can I download the result?
Yes. After calculation, use the CSV button for spreadsheet data. Use the print option to save the visible calculation as a PDF file.