.house-generator-calculator-container {
font-family: Arial, sans-serif;
max-width: 850px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e0e0e0;
border-radius: 10px;
background-color: #ffffff;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}
.house-generator-calculator-container h2 {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 28px;
}
.house-generator-calculator-container p {
margin-bottom: 18px;
line-height: 1.7;
color: #34495e;
}
.house-generator-calculator-container .calculator-section {
background-color: #f8f9fa;
border: 1px solid #dee2e6;
border-radius: 8px;
padding: 20px;
margin-bottom: 25px;
}
.house-generator-calculator-container .calculator-section h3 {
color: #34495e;
margin-top: 0;
margin-bottom: 15px;
font-size: 22px;
border-bottom: 2px solid #e9ecef;
padding-bottom: 10px;
}
.house-generator-calculator-container #applianceTable {
width: 100%;
border-collapse: collapse;
margin-bottom: 20px;
}
.house-generator-calculator-container #applianceTable th,
.house-generator-calculator-container #applianceTable td {
border: 1px solid #ced4da;
padding: 10px;
text-align: left;
vertical-align: middle;
}
.house-generator-calculator-container #applianceTable th {
background-color: #e9ecef;
color: #495057;
font-weight: bold;
}
.house-generator-calculator-container #applianceTable td:first-child {
font-weight: 500;
color: #34495e;
}
.house-generator-calculator-container #applianceTable input[type="number"],
.house-generator-calculator-container #applianceTable input[type="text"] {
width: 90px;
padding: 8px;
border: 1px solid #ced4da;
border-radius: 5px;
font-size: 14px;
box-sizing: border-box;
}
.house-generator-calculator-container #applianceTable input[type="text"] {
width: 150px;
}
.house-generator-calculator-container #applianceTable input[type="checkbox"] {
transform: scale(1.3);
margin-left: 15px;
vertical-align: middle;
cursor: pointer;
}
.house-generator-calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #28a745;
color: white;
border: none;
border-radius: 6px;
font-size: 18px;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 20px;
}
.house-generator-calculator-container button:hover {
background-color: #218838;
transform: translateY(-1px);
}
.house-generator-calculator-container #result {
margin-top: 30px;
padding: 20px;
border: 1px solid #c3e6cb;
background-color: #d4edda;
border-radius: 8px;
color: #155724;
font-size: 16px;
line-height: 1.8;
}
.house-generator-calculator-container #result h3 {
margin-top: 0;
color: #155724;
font-size: 24px;
border-bottom: 1px solid #a7d8b5;
padding-bottom: 10px;
margin-bottom: 15px;
}
.house-generator-calculator-container #result p {
margin-bottom: 8px;
color: #155724;
}
.house-generator-calculator-container #result strong {
color: #0f5132;
}
.house-generator-calculator-container .note {
color: #856404;
background-color: #fff3cd;
border-color: #ffeeba;
padding: 10px 15px;
border-radius: 5px;
margin-top: 15px;
font-size: 14px;
}
.house-generator-calculator-container .warning {
color: #721c24;
background-color: #f8d7da;
border-color: #f5c6cb;
padding: 10px 15px;
border-radius: 5px;
margin-top: 15px;
font-weight: bold;
}
function calculateGeneratorSize() {
var totalRunningWatts = 0;
var largestStartingWattsDifference = 0; // This will store the largest (Starting Watts – Running Watts)
// Define appliances and their IDs
var appliances = [
{ name: "refrigerator", defaultRun: 150, defaultStart: 600 },
{ name: "freezer", defaultRun: 100, defaultStart: 400 },
{ name: "sumpPump", defaultRun: 800, defaultStart: 1300 },
{ name: "wellPump", defaultRun: 1000, defaultStart: 2000 },
{ name: "furnaceFan", defaultRun: 800, defaultStart: 1600 },
{ name: "microwave", defaultRun: 1000, defaultStart: 1500 },
{ name: "tv", defaultRun: 100, defaultStart: 100 },
{ name: "lights", defaultRun: 100, defaultStart: 100 },
{ name: "ac", defaultRun: 4000, defaultStart: 12000 },
{ name: "custom", defaultRun: 0, defaultStart: 0 } // For the custom row
];
for (var i = 0; i < appliances.length; i++) {
var appliance = appliances[i];
var isChecked = document.getElementById("chk_" + appliance.name).checked;
if (isChecked) {
var qty = parseFloat(document.getElementById("qty_" + appliance.name).value);
var runWatts = parseFloat(document.getElementById("run_" + appliance.name).value);
var startWatts = parseFloat(document.getElementById("start_" + appliance.name).value);
if (isNaN(qty) || qty < 0) qty = 0;
if (isNaN(runWatts) || runWatts < 0) runWatts = 0;
if (isNaN(startWatts) || startWatts largestStartingWattsDifference) {
largestStartingWattsDifference = currentApplianceSurgeDifference;
}
}
}
var recommendedRunningCapacity = totalRunningWatts;
var recommendedSurgeCapacity = totalRunningWatts + largestStartingWattsDifference;
var resultDiv = document.getElementById("result");
var resultHTML = "
House Generator Size Calculator
Use this calculator to determine the appropriate generator size (in Watts) needed to power your essential home appliances during an electrical outage. Accurately sizing your generator ensures you have enough power without overspending on an unnecessarily large unit.
Enter the quantity, running watts, and starting watts for each appliance you wish to power. Check the 'Include?' box for each item you want to add to the calculation. If an appliance is not listed, use the 'Custom Appliance' row.
Appliance Load Inputs
| Appliance | Quantity | Running Watts (each) | Starting Watts (each) | Include? |
|---|---|---|---|---|
| Refrigerator (Energy Star) | ||||
| Freezer (Energy Star) | ||||
| Sump Pump (1/3 HP) | ||||
| Well Pump (1/2 HP) | ||||
| Furnace Fan (Gas, 1/2 HP) | ||||
| Microwave (1000W) | ||||
| Television (LED 50″) | ||||
| Lights (LED, 10 bulbs) | ||||
| Central AC (3-ton) | ||||
Understanding Generator Sizing for Your Home
A home generator can be a lifesaver during power outages, keeping your essential appliances running and maintaining comfort and safety. However, choosing the right size generator is crucial. An undersized generator won't power everything you need, while an oversized one is an unnecessary expense and consumes more fuel.
Running Watts vs. Starting Watts: The Key Difference
When sizing a generator, you need to understand two critical wattage ratings:
- Running Watts (Continuous Watts): This is the power an appliance needs to operate continuously once it's turned on. For example, a refrigerator might need 150 running watts to keep its compressor going.
- Starting Watts (Surge Watts): Many motor-driven appliances (like refrigerators, freezers, sump pumps, and air conditioners) require a brief, extra burst of power to start their motors. This surge can be 2-3 times their running wattage. Once the motor starts, the power requirement drops back to the running watts.
Your generator must be able to handle the combined running watts of all appliances you want to operate simultaneously, PLUS the single largest starting wattage requirement of any appliance that might kick on while others are already running.
How to Use the Calculator
- Identify Essential Appliances: Decide which appliances are critical during a power outage. This might include your refrigerator, freezer, furnace fan, sump pump, some lights, and perhaps a television or microwave.
- Find Wattage Ratings: Look for the running and starting wattage on the appliance's label, in its owner's manual, or search online. If only running watts are listed for a motor-driven appliance, a general rule of thumb is to multiply the running watts by 2 or 3 to estimate starting watts. For non-motorized items (like lights, TVs), starting watts are usually equal to running watts.
- Input Values: Enter the quantity, running watts, and starting watts for each appliance into the calculator. Check the 'Include?' box for every item you want to power. Use the 'Custom Appliance' row for anything not pre-listed.
- Calculate: Click the "Calculate Generator Size" button.
- Interpret Results: The calculator will provide two key figures:
- Recommended Generator Running Capacity: This is the total continuous power needed for all selected appliances.
- Recommended Generator Surge Capacity: This is the maximum power spike your generator needs to handle when the largest motor-driven appliance starts up while others are running.
Important Considerations Beyond Watts
- Fuel Type: Generators run on various fuels like gasoline, propane, natural gas, or diesel. Consider availability, storage, and run time.
- Generator Type:
- Portable Generators: More affordable, can be moved, but require manual setup and refueling.
- Standby Generators: Permanently installed, automatically turn on when power fails, often run on natural gas or propane, and can power a whole house.
- Automatic Transfer Switch (ATS): For standby generators, an ATS safely disconnects your home from the utility grid and connects it to the generator, then reverses the process when utility power returns.
- Installation: Standby generators require professional installation, including electrical and fuel line connections. Portable generators also need safe setup and proper extension cords.
- Noise Levels: Generators can be noisy. Check decibel ratings, especially if you have close neighbors.
- Future Needs: Consider if you might add more appliances or expand your power needs in the future.
Safety First!
Always operate generators outdoors in a well-ventilated area, far from windows and doors, to prevent carbon monoxide poisoning. Never run a generator indoors or in a garage. Follow all manufacturer instructions and local codes for safe operation and installation.
By carefully calculating your wattage needs and considering these factors, you can confidently choose a generator that provides reliable power for your home when you need it most.