Free tool
VA to Amps Calculator
VA divided by volts — and by 1.732 on three-phase. The arithmetic is one line. The mistake worth catching is treating the watt figure on the same label as if it were the VA.
VA ÷ volts, with no power factor
amps = VA ÷ volts on single-phase and DC, and amps = VA ÷ (volts × √3) on three-phase using the line-to-line voltage. A 1,500 VA UPS at 120 V is 12.5 A at full output; a 40 VA transformer on its 24 V side is about 1.67 A.
No power factor is applied, because VA already is apparent power. Where a label prints both — 1500 VA / 900 W — the current follows the VA. Dividing the watts by the voltage instead gives 7.5 A and understates it by 40%. The tool shows both figures when you enter the watt rating.
The rating
The nameplate VA. For kVA, multiply by 1,000.
The voltage the VA is rated at.
UPS units print both, such as 1500 VA / 900 W. Leave blank if the label gives only VA.
The answer
Current at the full VA rating
12.50 A
amps = VA ÷ volts → 1,500 ÷ (120 V)
No power factor is applied, and none should be: VA is already apparent power, the quantity current is drawn against.
What the number is
The current at the equipment's full VA rating. On a UPS or an inverter that is the output side. The current it draws from the wall is a different figure — higher, because of conversion losses and battery charging — and it is printed separately as the input rating.
What this does not tell you
A breaker or wire size. Overcurrent protection and conductor ampacity depend on the equipment's listing and instructions, continuous-load rules, conductor material, insulation and terminal ratings, and conditions of use — none of which are entered here.
Whether a load fits. A UPS is limited by VA and watts; a load can fit one and not the other.
Informational use only, please verify before you rely on it
This reproduces standard conversion arithmetic from apparent power in volt-amperes to current for DC, single-phase and three-phase systems. It is a preparation aid, not a determination and not a design. It does not size overcurrent protection or conductors, which depend on the equipment's listing and instructions, continuous-load rules, conductor material, insulation and terminal ratings, and conditions of use. On a UPS or inverter the VA rating describes the output; the input current is a separate nameplate figure. Confirm against the equipment nameplate and with the authority having jurisdiction.
This tool is provided for general informational and educational purposes only. Its output is an illustrative estimate generated from the values you enter and from general assumptions that will not match every deal, market, lender, or homeowner. It is not tax, legal, accounting, financial, or professional advice, and it is not a quote, an offer, a credit decision, or a guarantee of pricing, approval, timing, savings, or eligibility.
You are solely responsible for independently confirming all information presented here including any figures, rates, fees, margins, timelines, tax treatment, and federal, state, local, or utility incentives, with the applicable lender, authority having jurisdiction, and your own qualified tax, legal, and financial advisors before acting on it, relying on it, or presenting it to a homeowner or any third party. Incentive programs, lender terms, and permitting requirements change frequently and vary by jurisdiction.
Seamless Home is not a tax advisor, law firm, lender, or licensed installing contractor, and makes no representation or warranty as to the accuracy, completeness, or currency of the information produced by this tool. To the fullest extent permitted by law, Seamless Home accepts no liability for any decision made or action taken in reliance on it.
Where a bare VA figure turns up
VA ratings sit on equipment whose load is not purely resistive, which is why the manufacturer states apparent power rather than watts: uninterruptible power supplies, small control and low-voltage transformers, inverters, and the power supplies inside electronics. The difference between the two figures is the power factor, and what power factor is explains why a 900 W load can still push a 1,500 VA unit to its limit.
For larger equipment rated in thousands of VA — utility and building transformers, generators — the kVA to amps calculator does the same arithmetic with standard transformer sizes, and the amps to kVA calculator runs it in reverse. When the starting figure is real power instead, the watts to amps calculator applies the power factor that this page deliberately leaves out. Which voltage a building actually has is its own question — single-phase vs three-phase power covers 120/240 V against 208Y/120 and 480Y/277.
Frequently Asked Questions
How do you convert VA to amps?+
Divide the VA rating by the voltage. On single-phase that is the whole calculation: 1,500 VA at 120 V is 12.5 A, and 100 VA at 24 V is about 4.2 A. On three-phase, divide by the voltage times the square root of three (about 1.732), using the line-to-line voltage: 10,000 VA at 208 V three-phase is about 27.8 A per line.
Why is there no power factor in a VA to amps conversion?+
Because VA is apparent power — volts times amps — and current is drawn against apparent power. Power factor is the ratio between watts and VA. It belongs in a watts to amps conversion, where the watt figure leaves part of the current out. Applying it to a VA figure divides by it twice and overstates the current.
Is VA the same as watts?+
Only when the power factor is 1, which is true on DC and for purely resistive AC loads such as heaters. For electronics, motors and anything with a power supply, watts are smaller than VA. A UPS labelled 1500 VA / 900 W can deliver 1,500 VA of apparent power or 900 W of real power, whichever limit the load reaches first.
How many amps is a 1500 VA UPS?+
At 120 V, 1,500 VA is 12.5 A at the output at full rating. That is the output limit, not the current the UPS draws from the wall. The input current is higher because of conversion losses and battery charging, and the manufacturer prints it separately — use that input figure when you are working out what the receptacle circuit carries.
How many amps is a 40 VA transformer?+
On its 24 V secondary, 40 VA ÷ 24 V is about 1.67 A — the most the low-voltage side can deliver at its rating. On its 120 V primary the same 40 VA is about 0.33 A. Which side you are asking about decides which voltage goes in the formula.
Which voltage do I use on three-phase?+
The line-to-line voltage: 208, 240 or 480. On a wye system written 208Y/120 or 480Y/277, the second number is line-to-neutral. Entering it into the three-phase formula overstates the current by a factor of about 1.73. The calculator flags 120 V and 277 V on three-phase and shows the corrected figure.
Is this a determination?+
No. It reproduces the standard conversion arithmetic as a preparation aid. It reports current at a nameplate VA rating and nothing else — not a breaker size, not a conductor size, and not whether a particular load fits a particular UPS or transformer. Confirm against the equipment's nameplate and instructions and with the authority having jurisdiction.
Related resources
kVA to Amps Calculator
The same conversion for transformers and generators, with standard sizes.
Learn more →Amps to kVA Calculator
Apparent power from a current and voltage — the reverse direction.
Learn more →Watts to Amps Calculator
Current from real power, with power factor applied.
Learn more →What Is Power Factor?
Why watts and VA differ, and which one current follows.
Learn more →Electrical scope, handled before it stalls the job
Seamless Home runs the design, permit and interconnection layer for the partners it works with, which is where an equipment rating that does not add up gets caught before install. Coverage is confirmed per service area rather than promised as blanket availability.
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