.va-calculator-container {
max-width: 600px;
margin: 20px auto;
padding: 25px;
background-color: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
.va-calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
font-size: 24px;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #555;
}
.form-group input, .form-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.form-group input:focus {
border-color: #0073aa;
outline: none;
}
.calc-btn {
width: 100%;
padding: 12px;
background-color: #0073aa;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background 0.3s;
}
.calc-btn:hover {
background-color: #005177;
}
.result-box {
margin-top: 20px;
padding: 15px;
background-color: #e8f4fc;
border: 1px solid #bce0fd;
border-radius: 4px;
text-align: center;
display: none;
}
.result-value {
font-size: 32px;
font-weight: bold;
color: #0073aa;
margin: 10px 0;
}
.result-label {
font-size: 14px;
color: #666;
}
.error-msg {
color: #d63638;
font-weight: bold;
text-align: center;
margin-top: 10px;
display: none;
}
.article-content {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #333;
font-family: Arial, sans-serif;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.article-content h3 {
color: #0073aa;
margin-top: 25px;
}
.article-content table {
width: 100%;
border-collapse: collapse;
margin: 20px 0;
}
.article-content table, .article-content th, .article-content td {
border: 1px solid #ddd;
}
.article-content th, .article-content td {
padding: 12px;
text-align: left;
}
.article-content th {
background-color: #f2f2f2;
}
.formula-box {
background: #f4f4f4;
padding: 15px;
border-left: 4px solid #0073aa;
font-family: monospace;
margin: 15px 0;
}
function calculateAmps() {
// 1. Get DOM elements
var phaseEl = document.getElementById("phaseSelect");
var vaEl = document.getElementById("vaInput");
var voltEl = document.getElementById("voltageInput");
var resultBox = document.getElementById("resultBox");
var ampResult = document.getElementById("ampResult");
var formulaDisplay = document.getElementById("formulaUsed");
var errorBox = document.getElementById("errorBox");
// 2. Parse values
var phase = parseInt(phaseEl.value);
var va = parseFloat(vaEl.value);
var volts = parseFloat(voltEl.value);
// 3. Reset display
errorBox.style.display = "none";
resultBox.style.display = "none";
// 4. Validation
if (isNaN(va) || isNaN(volts)) {
errorBox.innerText = "Please enter valid numeric values for Power and Voltage.";
errorBox.style.display = "block";
return;
}
if (volts <= 0) {
errorBox.innerText = "Voltage must be greater than zero.";
errorBox.style.display = "block";
return;
}
// 5. Calculation Logic
var amps = 0;
var formulaText = "";
if (phase === 1) {
// Single Phase Formula: I = S / V
amps = va / volts;
formulaText = "Formula Used: I = " + va + " VA / " + volts + " V";
} else {
// Three Phase Formula (assuming Line-to-Line voltage): I = S / (V * sqrt(3))
// Sqrt(3) is approximately 1.73205
var sqrt3 = 1.73205080757;
amps = va / (volts * sqrt3);
formulaText = "Formula Used: I = " + va + " VA / (" + volts + " V × √3)";
}
// 6. Display Result
ampResult.innerText = amps.toFixed(2) + " A";
formulaDisplay.innerText = formulaText;
resultBox.style.display = "block";
}
How to Convert Volt-Amperes (VA) to Amps
Understanding the relationship between power and current is essential for electricians, electrical engineers, and DIY enthusiasts dealing with electrical circuits. While Wattage is the most common unit of power for consumers, Volt-Amperes (VA) is the standard unit for Apparent Power, which is critical when sizing wiring, transformers, and circuit breakers.
This VA to Amps Calculator simplifies the process of determining the electrical current flowing through a system based on its apparent power and voltage. Below, we break down the math and physics behind these conversions for both single-phase and three-phase systems.
The Difference Between VA and Watts
Before converting, it is important to distinguish between VA (Apparent Power) and Watts (Real Power). Watts represent the actual power consumed by the equipment to do useful work. VA represents the total power flowing through the circuit, including both the useful power and the reactive power needed to sustain magnetic fields in inductive loads (like motors).
Since wires and breakers must handle the total current regardless of whether it does useful work, we use VA to calculate Amperage for circuit sizing.
Formulas for VA to Amps Conversion
The formula to convert VA to Amps changes depending on whether your electrical system is Single Phase (typical for residential homes) or Three Phase (typical for industrial and commercial settings).
1. Single Phase Formula
For most household electronics and residential appliances, you use the Single Phase formula. The relationship is linear.
I = S / V
Where:
I = Current in Amperes (A)
S = Apparent Power in Volt-Amperes (VA)
V = Voltage in Volts (V)
Example: You have a transformer rated at 500 VA connected to a 120V circuit.
- Calculation: 500 VA / 120 V = 4.17 Amps.
2. Three Phase Formula
For industrial machinery, large motors, or commercial power distribution, Three Phase power is used. Because three-phase power provides three alternating currents separated by a phase angle, we must include the square root of 3 (√3 ≈ 1.732) in the calculation.
I = S / (V × √3)
Where:
I = Current in Amperes (A)
S = Apparent Power in Volt-Amperes (VA)
V = Line-to-Line Voltage (V)
√3 ≈ 1.732
Example: A 3-phase motor is rated for 15,000 VA (15 kVA) running on 480V.
- Calculation: 15,000 VA / (480 V × 1.732)
- Denominator: 480 × 1.732 = 831.36
- Final: 15,000 / 831.36 = 18.04 Amps.
Why is this Calculation Important?
Converting VA to Amps is primarily done for safety and equipment sizing. If you know the VA rating of a transformer or a UPS (Uninterruptible Power Supply), you must convert that to Amps to ensure you do not overload the circuit breaker protecting it.
| Apparent Power (VA) |
Voltage (V) |
Phase |
Current (Amps) |
| 1000 VA |
120 V |
Single |
8.33 A |
| 2000 VA |
240 V |
Single |
8.33 A |
| 5000 VA |
208 V |
Three Phase |
13.88 A |
| 10000 VA |
480 V |
Three Phase |
12.03 A |
Frequently Asked Questions
Can I convert kVA to Amps with this?
Yes. 1 kVA is equal to 1,000 VA. Simply multiply your kVA value by 1,000 before entering it into the "Apparent Power" field above. For example, 5 kVA = 5,000 VA.
Does Power Factor affect this calculation?
No. When converting VA to Amps, the Power Factor is already accounted for within the VA unit itself. If you were converting Watts to Amps, you would need to divide by the Power Factor. Because VA is "Apparent Power," it is the direct product of Volts and Amps.