.fuel-calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-container {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.calc-row {
display: flex;
flex-wrap: wrap;
gap: 20px;
margin-bottom: 20px;
}
.calc-group {
flex: 1;
min-width: 200px;
display: flex;
flex-direction: column;
}
.calc-group label {
font-weight: 600;
margin-bottom: 8px;
color: #2c3e50;
font-size: 14px;
}
.calc-input, .calc-select {
padding: 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
width: 100%;
box-sizing: border-box;
transition: border-color 0.2s;
}
.calc-input:focus, .calc-select:focus {
border-color: #007bff;
outline: none;
}
.calc-btn {
background-color: #007bff;
color: white;
border: none;
padding: 14px 24px;
font-size: 16px;
font-weight: 600;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
margin-top: 10px;
}
.calc-btn:hover {
background-color: #0056b3;
}
.result-box {
background-color: #fff;
border: 1px solid #dee2e6;
border-radius: 4px;
padding: 20px;
margin-top: 25px;
display: none;
}
.result-title {
font-size: 18px;
color: #495057;
margin-bottom: 15px;
border-bottom: 2px solid #007bff;
padding-bottom: 10px;
display: inline-block;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #f1f3f5;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 500;
color: #6c757d;
}
.result-value {
font-weight: 700;
font-size: 18px;
color: #212529;
}
.helper-text {
font-size: 12px;
color: #6c757d;
margin-top: 5px;
}
/* Article Styling */
.content-section h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 1px solid #eee;
padding-bottom: 10px;
}
.content-section h3 {
color: #34495e;
margin-top: 25px;
}
.content-section ul {
padding-left: 20px;
}
.content-section li {
margin-bottom: 10px;
}
.info-table {
width: 100%;
border-collapse: collapse;
margin: 20px 0;
}
.info-table th, .info-table td {
border: 1px solid #dee2e6;
padding: 10px;
text-align: left;
}
.info-table th {
background-color: #f8f9fa;
}
function updateDensity() {
var preset = document.getElementById('fuelPreset').value;
var densityInput = document.getElementById('densityVal');
var densityUnit = document.getElementById('densityUnit');
// Set unit to kg/L for simplicity when using presets
if (preset === 'gasoline') {
densityInput.value = 0.74;
densityUnit.value = 'kgl';
} else if (preset === 'diesel') {
densityInput.value = 0.85;
densityUnit.value = 'kgl';
} else if (preset === 'ethanol') {
densityInput.value = 0.789;
densityUnit.value = 'kgl';
} else if (preset === 'e85') {
densityInput.value = 0.78;
densityUnit.value = 'kgl';
} else if (preset === 'methanol') {
densityInput.value = 0.792;
densityUnit.value = 'kgl';
} else if (preset === 'jeta') {
densityInput.value = 0.804;
densityUnit.value = 'kgl';
}
}
function calculateMassFlow() {
// Get Input Elements
var flowInput = document.getElementById('volumetricFlow').value;
var flowUnit = document.getElementById('flowUnit').value;
var densityInput = document.getElementById('densityVal').value;
var densityUnit = document.getElementById('densityUnit').value;
// Validation
if (flowInput === "" || densityInput === "") {
alert("Please enter both volumetric flow rate and density.");
return;
}
var flow = parseFloat(flowInput);
var density = parseFloat(densityInput);
if (isNaN(flow) || isNaN(density)) {
alert("Please enter valid numbers.");
return;
}
// Step 1: Normalize Flow to Liters per Hour (L/h)
var flowInLh = 0;
switch(flowUnit) {
case 'lh':
flowInLh = flow;
break;
case 'lmin':
flowInLh = flow * 60;
break;
case 'galh': // US Gallons
flowInLh = flow * 3.78541;
break;
case 'ccmin':
flowInLh = (flow / 1000) * 60;
break;
case 'm3h':
flowInLh = flow * 1000;
break;
}
// Step 2: Normalize Density to kg/L
var densityInKgL = 0;
switch(densityUnit) {
case 'kgl': // kg/L is same as g/cm3
densityInKgL = density;
break;
case 'kgm3':
densityInKgL = density / 1000;
break;
case 'lbgal': // lb / US Gallon
densityInKgL = density * 0.119826;
break;
case 'lbft3':
densityInKgL = density * 0.0160185;
break;
}
// Step 3: Calculate Mass Flow in kg/h (Base Unit)
// Formula: Mass Flow = Volumetric Flow * Density
var massFlowKgh = flowInLh * densityInKgL;
// Step 4: Convert to Output Units
var massFlowLbh = massFlowKgh * 2.20462; // kg to lb
var massFlowGs = (massFlowKgh * 1000) / 3600; // kg/h to g/s
// Display Results
document.getElementById('results').style.display = 'block';
document.getElementById('resKgh').innerText = massFlowKgh.toFixed(4);
document.getElementById('resLbh').innerText = massFlowLbh.toFixed(4);
document.getElementById('resGs').innerText = massFlowGs.toFixed(4);
}
Understanding Fuel Mass Flow Rate
The Fuel Mass Flow Rate is a critical parameter in engineering, particularly in automotive engine tuning, aerospace propulsion, and chemical process engineering. Unlike volumetric flow rate (which measures the volume of fuel moving per unit of time), mass flow rate measures the actual weight or mass of the fuel being consumed or transported.
This distinction is vital because the energy content of fuel is directly proportional to its mass, not its volume. Fuel volume changes significantly with temperature due to thermal expansion, whereas mass remains constant. For accurate air-fuel ratio (AFR) calculations in combustion engines, engineers must rely on mass flow data.
The Mass Flow Rate Formula
The calculation relies on the fundamental relationship between mass, volume, and density. The primary formula used by this calculator is:
ṁ = Q × ρ
Where:
- ṁ (m-dot): Mass Flow Rate (typically in kg/h or lb/h)
- Q: Volumetric Flow Rate (e.g., L/h, gal/h)
- ρ (rho): Density of the fuel (e.g., kg/L, lb/gal)
Common Fuel Densities
To obtain accurate results, you must use the specific density of the fuel at its operating temperature. Here are standard approximation values at 15°C (59°F):
| Fuel Type |
Density (kg/L) |
Density (lb/gal) |
| Gasoline (Unleaded) |
0.720 – 0.775 |
6.00 – 6.47 |
| Diesel (No. 2) |
0.820 – 0.860 |
6.84 – 7.18 |
| Ethanol (E100) |
0.789 |
6.58 |
| Methanol |
0.792 |
6.61 |
| Jet A / Kerosene |
0.804 |
6.71 |
Why Convert Volumetric Flow to Mass Flow?
1. Engine Tuning (EFI)
Electronic Fuel Injection (EFI) systems calculate the required fuel based on the mass of air entering the engine. Fuel injectors are often rated in volumetric flow (e.g., cc/min) or mass flow (lb/h). Converting between these ensures the ECU delivers the precise stoichiometric ratio required for combustion.
2. Temperature Compensation
As fuel gets hotter, it expands. A gallon of hot gasoline contains less actual fuel mass (and therefore less chemical energy) than a gallon of cold gasoline. By calculating mass flow, engineers can ignore the volume fluctuations caused by temperature changes.
3. Pump Sizing
When sizing fuel pumps for high-performance applications, it is crucial to ensure the pump can deliver the required mass of fuel to support the target horsepower, considering the specific gravity of the fuel being used (especially relevant when switching from Gasoline to Ethanol/E85).