kVA to Amps Calculator – How Many Amps Do You Need?

The kVA to Amps Calculator above works out the current in amps once you know the equipment's kVA rating, voltage, and phase type.

Enter the kVA, pick the voltage, choose single-phase or three-phase, and hit calculate. For three-phase systems, you'll also need to choose between line-to-line and line-to-neutral voltage.

This calculation comes up a lot when you're checking a UPS, generator, transformer, inverter, or similar equipment and need to know what current it's actually pulling.

kVA alone doesn't tell you the current, though. You need the voltage and the type of electrical system too — leave either one out and the number means nothing.

How to Convert kVA to Amps

The formula isn't the same for single-phase and three-phase systems, so the first thing to nail down is which one you're dealing with.

For a single-phase system:

Amps = kVA × 1000 ÷ Voltage

For a balanced three-phase system using line-to-line voltage:

Amps = kVA × 1000 ÷ (√3 × Voltage)

√3 works out to roughly 1.732, so in practice the three-phase formula is usually written as:

Amps = kVA × 1000 ÷ (1.732 × Voltage)

What you need going in:

• kVA rating
• Voltage in volts
• Phase type
• Line-to-line or line-to-neutral voltage, where it applies

The calculator applies the appropriate calculation based on the options you select.

Get the apparent power from your kW value using our kW to kVA Calculator.

Single-Phase kVA to Amps Calculator Formula

For a single-phase AC circuit:

I = kVA × 1000 ÷ V

Where:

• I = current in amperes
• kVA = apparent power
• V = voltage in volts

10 kVA at 230V

Say you've got a single-phase UPS rated at 10 kVA, running at 230V.

I = 10 × 1000 ÷ 230

I = 43.48 A

So the current works out to 43.48 A.

Same method for any other single-phase rating — just make sure you're using the actual rated voltage, not a rounded assumption.

Three-Phase kVA to Amps Calculator Formula

For a balanced three-phase system using line-to-line voltage:

I = kVA × 1000 ÷ (√3 × V)

Or with 1.732 in place of √3:

I = kVA × 1000 ÷ (1.732 × V)

That 1.732 is just √3, and it shows up throughout three-phase power calculations because of how the three phases relate to each other.

100 kVA at 415V

A three-phase transformer rated 100 kVA at 415V:

I = 100 × 1000 ÷ (1.732 × 415)

I ≈ 139.12 A

Why Voltage Matters

A question that comes up a lot:

"How many amps is 100 kVA?"

There's no single answer — not without knowing the voltage and how many phases you're working with.

For 100 kVA:

System	Voltage	Current
Single-phase	230V	434.78 A
Three-phase	400V	144.34 A
Three-phase	415V	139.12 A
Three-phase	480V	120.28 A

Same kVA rating across the board, but the current shifts every time the voltage or phase setup changes.

That's the whole reason kVA and voltage have to be looked at together, not separately.

Convert apparent power into real power with the kVA to kW Calculator.

Line-to-Line vs Line-to-Neutral Voltage

This is where people trip up most often in a three-phase calculation.

The standard three-phase formula with √3 assumes line-to-line voltage:

I = kVA × 1000 ÷ (1.732 × V)

If what you've got is line-to-neutral voltage instead, the formula changes to:

I = kVA × 1000 ÷ (3 × V)

So before you plug in a number, check which voltage type it actually is.

On a real job, that means checking the equipment nameplate, drawings, or spec sheet — not guessing.

Common kVA to Amps Values at 230V Single-Phase

kVA	Current
1 kVA	4.35 A
2 kVA	8.70 A
5 kVA	21.74 A
7.5 kVA	32.61 A
10 kVA	43.48 A
15 kVA	65.22 A
20 kVA	86.96 A
25 kVA	108.70 A
50 kVA	217.39 A
100 kVA	434.78 A

Worked out from:

Amps = kVA × 1000 ÷ 230

Find the current drawn by your electrical load with the Free kW to Amps Calculator.

Common kVA to Amps Values at 415V Three-Phase

kVA	Current
1 kVA	1.39 A
2 kVA	2.78 A
5 kVA	6.96 A
7.5 kVA	10.43 A
10 kVA	13.91 A
15 kVA	20.87 A
20 kVA	27.82 A
25 kVA	34.78 A
50 kVA	69.56 A
100 kVA	139.12 A
250 kVA	347.80 A
500 kVA	695.60 A

Worked out from:

Amps = kVA × 1000 ÷ (1.732 × 415)

What Does the Calculated Current Actually Tell You?

It gives you a starting point — not the final word.

You'll typically need this number when you're looking at:

• UPS capacity
• Generator loading
• Transformer loading
• Distribution circuits
• Breaker requirements
• Cable calculations
• Equipment ratings
• Electrical design

But don't stop there and call it your breaker or cable size.

The actual selection also depends on conductor ampacity, installation method, ambient temperature, grouping, voltage drop, protection requirements, local code, and whatever the manufacturer specifies.

The calculator hands you the current. Everything after that still needs checking.

See how many kilowatts your given current represents using the Amps to Kilowatts Calculator.

kVA to Amps for a Transformer

A kVA transformer is rated by its apparent power, so once you know the rating and the rated voltage, finding the current is straightforward.

For a three-phase transformer:

I = kVA × 1000 ÷ (1.732 × V)

100 kVA Transformer at 415V

I = 100 × 1000 ÷ (1.732 × 415)

I ≈ 139.12 A

One thing to watch: which side of the transformer are you actually checking?

Primary and secondary voltages are different, so the current on each side is different too. Don't reuse one voltage figure for both sides — that's an easy way to get a wrong answer.

kVA to Amps for a Generator

Generators are usually rated in kVA, which makes this calculation come up often for sizing checks.

Say a generator is rated:

• 250 kVA
• 415V
• Three-phase

I = 250 × 1000 ÷ (1.732 × 415)

I ≈ 347.80 A

That's the current at the nameplate rating — but for sizing and planning a generator, running current isn't the whole picture.

Motors, compressors, pumps, and similar loads can pull a high starting current well above their running current. Size the generator on running load alone, and it may struggle the moment a large motor kicks in.

A Real UPS Selection Experience

On one industrial UPS project, we needed backup for machines like VMC, HMC, TC, and VTL, a special-purpose machine, and server equipment.

The goal wasn't just to keep the machines running through a power cut — it was to avoid the damage or process issues a sudden interruption can cause on that kind of equipment.

We started with a load list. For each machine, we checked the rated power and whether it was given in kW or kVA, then looked at how much backup time was actually needed.

Backup time drives the battery bank directly — longer backup, bigger battery requirement. That's why I tend to treat the UPS and battery bank as one system from the start, rather than picking the UPS first and figuring out batteries later.

We built in roughly 15–25% extra capacity for future load growth, so a moderate increase down the line wouldn't push the UPS to its limit right away.

For this application, we went with an Online / Double Conversion UPS.

Battery choice took some thought too — long-term reliability, available space, and maintenance all factored in, and we ended up going with Lithium-ion batteries.

For the critical load, we used an N+1 arrangement, so if one UPS unit goes down for a fault or maintenance, the load still has backup.

Given the size of the load, a three-phase UPS system made sense — it gave us better control over phase distribution and balancing.

A simple kVA-to-amps number ends up being just one small piece of a much bigger electrical decision like this.

UPS Battery Backup and Room Conditions

Battery selection isn't only about how many batteries you need.

Backup time, battery technology, available space, maintenance access, and the operating environment all play into it.

Temperature especially shouldn't be an afterthought.

For this UPS and battery room, we installed air conditioning to keep the temperature under control, plus a temperature display so anyone could check the room condition at a glance.

Things we looked at:

• Ventilation
• Ambient temperature
• Battery-room space
• Maintenance access
• Temperature monitoring
• Cooling requirements

The battery room isn't just a storage space — it's part of the UPS installation itself.

Why Three-Phase Works Better for Larger Loads

For bigger industrial loads, three-phase distribution generally makes phase balancing and power distribution easier to manage.

Machines can be spread across the phases, and the whole system can be designed around how the load is actually arranged.

Which is also why getting the voltage and phase type right before running the calculation matters so much.

The calculator covers AC single-phase, AC three-phase, and DC/inverter options, with line-to-line and line-to-neutral selections for the three-phase case.

Is Power Factor Part of the kVA to Amps Formula?

Short answer — no, not in this calculation.

kVA already represents the total, or "apparent," side of the power picture, so the standard current formula doesn't need a power factor input at all. You only start pulling power factor into the math when you're working the other direction — going from actual working power in kW and trying to figure out kVA, or moving between the two.

We've broken that whole kW-kVA-PF relationship down separately on the site, so there's no point rehashing it here.

The takeaway for this page:

Got kVA, voltage, and phase type? That's everything the standard kVA-to-amps formula needs — power factor doesn't come into it.

What About the DC (Inverter) Option?

The calculator also has a DC (Inverter) setting.

Here, the relationship is:

I = kVA × 1000 ÷ V

Handy for inverter applications where the rating and voltage are specified in a way that fits this calculation.

If your inverter's rated only in watts or kW, don't just treat that number as kVA — check the manufacturer's spec sheet first.

Common Mistakes When Converting kVA to Amps

#1. Using the wrong voltage

The right formula with the wrong voltage still gives you a wrong answer. Always confirm against the nameplate or system documentation.

#2. Using a single-phase formula for three-phase equipment

The balanced three-phase formula needs that √3 (about 1.732) factor. Drop it, and the answer is off by a wide margin.

#4. Mixing up line-to-line and line-to-neutral voltage

Know which one the formula you're using expects. The standard √3 formula wants line-to-line voltage.

#5. Assuming every 100 kVA load has the same current

It doesn't — current shifts with voltage and phase configuration every time.

#6. Treating the calculated current as the final breaker size

It's one input among several. Breaker, cable, and protection selection all need checking against the actual installation and applicable code.

#7. Ignoring starting current

Motors can draw far more current at startup than during normal running — worth remembering when sizing a generator, UPS, transformer, or any source feeding motor-driven equipment.

#8. Looking only at the kVA rating

In real projects, kVA is just one factor. Future load growth, backup time, redundancy, battery needs, operating conditions, and the actual load profile all matter too.

How Do I Check the Voltage Before Calculating?

Start with the nameplate or the technical documentation.

Depending on the equipment and where it's installed, you might see:

• 120V
• 208V
• 230V
• 240V
• 400V
• 415V
• 480V

India typically runs 230V single-phase and 415V three-phase. In the US, 120V, 208V, 240V, and 480V systems are all common.

Don't pick a voltage just because it's the usual one where you are — use the actual rated voltage of the equipment or system in front of you.

Quick kVA to Amps Formulas

Single-phase:

Amps = kVA × 1000 ÷ Voltage

Three-phase, line-to-line voltage:

Amps = kVA × 1000 ÷ (1.732 × Voltage)

Three-phase, line-to-neutral voltage:

Amps = kVA × 1000 ÷ (3 × Voltage)

Keep your units consistent, and use the version that matches your phase and voltage type.

For additional electrical formulas and reference calculations, see ABB's electrotechnical formulas guide.

FAQs

Conclusion

The kVA to Amps Calculator gives you a fast way to go from a known kVA rating to the current it draws.

Enter the kVA, select the rated voltage, pick the phase type, and run it. On a three-phase system, double-check you've picked the right voltage type before calculating.

The calculator shows the result in amps, mA, and kA.

That covers a quick estimate. For actual electrical work, take one more step before using the number for equipment size, breaker selection, transformer sizing, or design — verify the nameplate, voltage, phase arrangement, and the specific application you're working on.

Disclaimer: The calculations provided by this kVA to Amps Calculator are for general informational and reference purposes only. Actual current, equipment sizing, cable selection, breaker ratings, and electrical installations should be verified using the equipment manufacturer's specifications, applicable electrical codes, and a qualified electrical professional. Do not use calculator results as the sole basis for electrical design or safety decisions.