Cessna 172S Weight and Balance Calculator | Professional Pilot Tools
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Center of Gravity (CG)
41.2″
Within Normal Limits
Total Weight
2321 lbs
Max Ramp: 2558
Total Moment
95625
in-lbs
Category
Normal
Utility Max: 2200
| Station |
Weight (lbs) |
Arm (in) |
Moment (in-lbs) |
CG Envelope Chart
Chart shows Normal (Blue) and Utility (Green) envelopes. Red dot is your current loading.
Detailed Guide: Cessna 172S Weight and Balance Calculator
Understanding the physics of your aircraft loading is critical for safe flight operations. This cessna 172s weight and balance calculator helps pilots quickly verify if their aircraft is within the certified center of gravity (CG) limits specified in the Pilot's Operating Handbook (POH). Whether you are planning a cross-country trip or a local training flight, ensuring you are within the weight and balance envelope is a legal and safety requirement.
What is a Cessna 172S Weight and Balance Calculator?
A cessna 172s weight and balance calculator is a flight planning tool designed to compute the loaded Center of Gravity (CG) of a Cessna 172 Skyhawk SP (Model S). It takes the basic empty weight of the specific airframe and adds the weights of pilots, passengers, baggage, and fuel to determine the total gross weight and the longitudinal location of the center of gravity.
This tool is essential for:
- Student Pilots: Learning to calculate loading scenarios for checkrides.
- Flight Instructors: Demonstrating the effects of heavy aft loading.
- Private Pilots: Quickly verifying safety before carrying passengers.
Misconceptions often arise regarding the "Utility Category." Many pilots believe they can perform spins at any weight, but the cessna 172s weight and balance calculator will show that Utility Category requires a significantly reduced gross weight and a more forward CG limit.
The calculation is based on the principle of moments. A moment is the rotational force created by a weight acting at a distance from a reference point (datum). In the Cessna 172S, the datum is the front face of the firewall.
The core formulas used are:
Moment = Weight × Arm
Center of Gravity (CG) = Total Moment ÷ Total Weight
| Variable |
Meaning |
Unit |
C172S Standard Arm |
| Basic Empty Weight |
Airframe + Oil + Unusable Fuel |
lbs |
~38-42″ (varies) |
| Front Pax |
Pilot & Co-Pilot |
lbs |
37.0″ |
| Rear Pax |
Backseat Passengers |
lbs |
73.0″ |
| Fuel |
Avgas (6 lbs/gal) |
lbs |
48.0″ |
| Baggage A |
Main Baggage Area |
lbs |
95.0″ |
| Baggage B |
Aft Baggage Area |
lbs |
123.0″ |
Practical Examples (Real-World Use Cases)
Example 1: The "Max Gross" Training Flight
A flight instructor and a student are planning a long cross-country. They fill the tanks and load heavy bags.
- Empty Weight: 1680 lbs (Arm 40.0″)
- Front Occupants: 400 lbs (Two large adults)
- Rear Occupants: 0 lbs
- Fuel: 53 Gallons (318 lbs)
- Baggage: 100 lbs
Result: Total Weight is 2498 lbs. The cessna 172s weight and balance calculator shows the CG is at 41.5 inches. This is within the Normal Category limits, but very close to Max Takeoff Weight (2550 lbs). Performance will be reduced.
Example 2: The "Aft CG" Danger Scenario
A pilot takes three friends for a scenic flight with light fuel to stay under weight.
- Front Occupants: 350 lbs
- Rear Occupants: 380 lbs
- Baggage: 50 lbs
- Fuel: 20 Gallons (120 lbs)
Result: Even if the total weight is legal, the heavy rear passengers shift the CG aft. If the calculation shows a CG of 47.5 inches, the aircraft is OUT OF LIMITS (limit is 47.3″). This configuration would make the aircraft unstable and difficult to recover from a stall. The calculator visually flags this danger.
How to Use This Cessna 172S Weight and Balance Calculator
- Enter Aircraft Data: Input the Basic Empty Weight and Moment Arm from the specific aircraft's POH (Section 6).
- Load Passengers: Enter weights for the pilot, co-pilot, and rear passengers.
- Add Cargo: Enter baggage weights for Area A and Area B. Note the 120 lb combined limit.
- Add Fuel: Enter fuel in gallons. The calculator converts this to lbs (6 lbs/gal).
- Analyze Results: Look at the visual graph. The red dot must be inside the blue (Normal) or green (Utility) polygon.
Key Factors That Affect Weight and Balance Results
Several variables impact your cessna 172s weight and balance calculator results and flight safety:
- Fuel Burn: As you burn fuel (Arm 48.0″), the weight decreases. Since the fuel tank arm is usually aft of the forward CG limit but forward of the aft passengers, burning fuel can shift the CG slightly. Always check your "Landing Weight" and balance.
- Baggage Placement: Placing heavy items in Baggage Area B (Arm 123.0″) has a massive leverage effect compared to Area A (Arm 95.0″). Moving items forward can often fix an aft-CG problem.
- Density Altitude: While not part of the weight calculation, a heavy aircraft performs significantly worse in high density altitude. If your calculator shows you are at Max Gross, ensure you have sufficient runway.
- Equipment Changes: If new avionics are installed, the Basic Empty Weight and Arm change. Always use current data.
- Utility Category Restrictions: To operate in the Utility category (allowed for spins), the cessna 172s weight and balance calculator must show the center of gravity between 35.0″ and 40.5″ and weight below 2200 lbs.
- Oil Weight: Standard Basic Empty Weight includes full oil. If your weight data is "Dry," you must add oil weight (approx 15 lbs at Arm -14.0″ roughly, check POH).
Frequently Asked Questions (FAQ)
1. Can I use this calculator for a Cessna 172M or 172N?
No. The limits, moment arms, and max weights differ between models. This tool is specifically a cessna 172s weight and balance calculator (Skyhawk SP).
2. What is the max ramp weight vs max takeoff weight?
For the C172S, Max Ramp Weight is 2558 lbs. You are allowed to taxi at this weight, assuming you will burn 8 lbs of fuel before takeoff, resulting in a Max Takeoff Weight of 2550 lbs.
3. What happens if the CG is too far aft?
An aft CG makes the aircraft unstable in pitch, makes stall recovery difficult or impossible, and reduces control effectiveness.
4. How much fuel is 53 gallons?
53 gallons of Avgas weighs approximately 318 lbs (at 6 lbs/gallon).
5. Can I put 120 lbs in Area A and 50 lbs in Area B?
No. While Area A holds 120 lbs and Area B holds 50 lbs individually, the combined maximum baggage allowance is 120 lbs total for the C172S.
6. Why is my result "Utility Category"?
If your total weight is under 2200 lbs and your CG is within the narrower utility limits, you are in the Utility Category, permitting limited aerobatic maneuvers like spins.
7. Does this calculator account for fuel burn during flight?
This calculator shows the loading at the current moment. You should calculate a second scenario with your expected fuel at landing to ensure you stay within limits throughout the flight.
8. Where can I find my aircraft's Basic Empty Weight?
Look in Section 6 (Weight and Balance) of the specific Pilot's Operating Handbook (POH) kept in the aircraft. It is updated whenever maintenance modifies the airframe.
Related Tools and Internal Resources
Explore more aviation planning tools:
Density Altitude Calculator
Determine aircraft performance based on temperature and pressure.
Crosswind Component Calculator
Calculate headwind and crosswind vectors for takeoff and landing.
VFR Flight Plan Generator
Organize your checkpoints, fuel burns, and headings.
Holding Pattern Entry Visualizer
Determine Direct, Parallel, or Teardrop entries instantly.
Top of Descent Calculator
Calculate the 3-degree glide path for smooth arrivals.
Fuel Endurance Calculator
Estimate range and time aloft based on GPH burn rates.
// Constants for C172S Physics
var ARM_FRONT_PAX = 37.0;
var ARM_REAR_PAX = 73.0;
var ARM_BAGGAGE_1 = 95.0;
var ARM_BAGGAGE_2 = 123.0;
var ARM_FUEL = 48.0;
var FUEL_WEIGHT_PER_GAL = 6.0;
// Limits
var MAX_RAMP_WEIGHT = 2558;
var MAX_TAKEOFF_WEIGHT = 2550;
var MAX_UTILITY_WEIGHT = 2200;
var MAX_BAGGAGE_TOTAL = 120;
// Envelope Points (Weight, CG)
// Normal Category Envelope
var ENV_NORMAL = [
{w: 2550, cg: 41.0}, // Top Left
{w: 2550, cg: 47.3}, // Top Right
{w: 1600, cg: 47.3}, // Bottom Right (Extrapolated down)
{w: 1600, cg: 35.0}, // Bottom Left
{w: 1950, cg: 35.0} // Kink point
];
// Utility Category Envelope
var ENV_UTILITY = [
{w: 2200, cg: 35.0}, // Top Left Kink
{w: 2200, cg: 40.5}, // Top Right
{w: 1600, cg: 40.5}, // Bottom Right
{w: 1600, cg: 35.0} // Bottom Left
// Note: From 1950 to 2200, fwd limit goes from 35.0 to 35.5 approx if linear,
// but C172S Utility Fwd limit is typically 35.0 up to 1950, then linear to 37.5 @ 2200?
// Let's use simplified common POH Utility:
// Fwd: 35.0 @ 1950, linear to 37.5 @ 2200.
// Aft: 40.5 @ all weights.
];
// Helper for linear interpolation
function interpolateFwdLimit(weight) {
if (weight = 2550) return 41.0;
// Linear between 1950 and 2550
var ratio = (weight – 1950) / (2550 – 1950);
return 35.0 + (ratio * (41.0 – 35.0));
}
function calculateWB() {
// 1. Get Inputs
var basicWeight = parseFloat(document.getElementById('basicEmptyWeight').value) || 0;
var basicArm = parseFloat(document.getElementById('emptyMomentArm').value) || 0;
var frontPax = parseFloat(document.getElementById('frontPax').value) || 0;
var rearPax = parseFloat(document.getElementById('rearPax').value) || 0;
var bag1 = parseFloat(document.getElementById('baggage1').value) || 0;
var bag2 = parseFloat(document.getElementById('baggage2').value) || 0;
var fuelGal = parseFloat(document.getElementById('fuelGallons').value) || 0;
// Validation for Baggage
if ((bag1 + bag2) > MAX_BAGGAGE_TOTAL) {
document.getElementById('baggage1').style.borderColor = "#dc3545";
document.getElementById('baggage2').style.borderColor = "#dc3545";
} else {
document.getElementById('baggage1').style.borderColor = "#dee2e6";
document.getElementById('baggage2').style.borderColor = "#dee2e6″;
}
// 2. Calculate Weights & Moments
var fuelWeight = fuelGal * FUEL_WEIGHT_PER_GAL;
var m_basic = basicWeight * basicArm;
var m_front = frontPax * ARM_FRONT_PAX;
var m_rear = rearPax * ARM_REAR_PAX;
var m_bag1 = bag1 * ARM_BAGGAGE_1;
var m_bag2 = bag2 * ARM_BAGGAGE_2;
var m_fuel = fuelWeight * ARM_FUEL;
var totalWeight = basicWeight + frontPax + rearPax + bag1 + bag2 + fuelWeight;
var totalMoment = m_basic + m_front + m_rear + m_bag1 + m_bag2 + m_fuel;
var cg = 0;
if (totalWeight > 0) {
cg = totalMoment / totalWeight;
}
// 3. Update Text Results
document.getElementById('resultWeight').innerText = totalWeight.toFixed(1) + " lbs";
document.getElementById('resultMoment').innerText = totalMoment.toFixed(0);
document.getElementById('resultCG').innerText = cg.toFixed(1) + '"';
// 4. Update Table
var tableBody = document.querySelector("#loadSchedule tbody");
tableBody.innerHTML = `
| Basic Empty Weight | ${basicWeight} | ${basicArm} | ${m_basic.toFixed(0)} |
| Front Pilots | ${frontPax} | ${ARM_FRONT_PAX} | ${m_front.toFixed(0)} |
| Rear Passengers | ${rearPax} | ${ARM_REAR_PAX} | ${m_rear.toFixed(0)} |
| Baggage A | ${bag1} | ${ARM_BAGGAGE_1} | ${m_bag1.toFixed(0)} |
| Baggage B | ${bag2} | ${ARM_BAGGAGE_2} | ${m_bag2.toFixed(0)} |
| Fuel (${fuelGal} gal) | ${fuelWeight} | ${ARM_FUEL} | ${m_fuel.toFixed(0)} |
| TOTALS |
${totalWeight.toFixed(1)} |
${cg.toFixed(1)} |
${totalMoment.toFixed(0)} |
`;
// 5. Determine Category Status
var statusEl = document.getElementById('resultStatus');
var catEl = document.getElementById('resultCategory');
var statusClass = "";
var statusText = "";
var categoryText = "Normal";
// Limits Logic
var fwdLimit = interpolateFwdLimit(totalWeight);
var aftLimit = 47.3;
var isNormal = false;
var isUtility = false;
// Check Normal
if (totalWeight = fwdLimit && cg <= aftLimit) {
isNormal = true;
}
// Check Utility
// Utility Fwd: 35.0 1950) {
// Linear interp 35.0 to 37.5 for range 1950-2200
utilFwd = 35.0 + ((totalWeight – 1950) / (2200 – 1950)) * (37.5 – 35.0);
}
if (totalWeight = utilFwd && cg <= 40.5) {
isUtility = true;
}
if (isUtility) {
statusClass = "status-utility";
statusText = "Utility Category OK";
categoryText = "Utility";
} else if (isNormal) {
statusClass = "status-safe";
statusText = "Normal Category OK";
categoryText = "Normal";
} else {
statusClass = "status-danger";
statusText = "OUT OF LIMITS";
categoryText = "Unsafe";
}
statusEl.className = "status-badge " + statusClass;
statusEl.innerText = statusText;
catEl.innerText = categoryText;
// 6. Draw Chart
drawChart(cg, totalWeight);
}
function drawChart(currentCG, currentWeight) {
var canvas = document.getElementById('cgChart');
var ctx = canvas.getContext('2d');
// Handle High DPI
var dpr = window.devicePixelRatio || 1;
var rect = canvas.getBoundingClientRect();
canvas.width = rect.width * dpr;
canvas.height = rect.height * dpr;
ctx.scale(dpr, dpr);
var w = rect.width;
var h = rect.height;
// Chart Bounds
var minCG = 34.0, maxCG = 49.0;
var minWt = 1500, maxWt = 2700;
// Helper to map values to pixels
function mapX(val) {
return ((val – minCG) / (maxCG – minCG)) * w;
}
function mapY(val) {
return h – ((val – minWt) / (maxWt – minWt)) * h;
}
// Clear
ctx.clearRect(0, 0, w, h);
// Draw Grid
ctx.strokeStyle = "#e9ecef";
ctx.lineWidth = 1;
ctx.beginPath();
for(var i=34; i<=49; i++) {
var x = mapX(i);
ctx.moveTo(x, 0); ctx.lineTo(x, h);
ctx.fillText(i, x+2, h-5);
}
for(var j=1500; j<=2700; j+=100) {
var y = mapY(j);
ctx.moveTo(0, y); ctx.lineTo(w, y);
ctx.fillText(j, 5, y-2);
}
ctx.stroke();
// Draw Normal Category Polygon
ctx.fillStyle = "rgba(0, 74, 153, 0.1)";
ctx.strokeStyle = "#004a99";
ctx.lineWidth = 2;
ctx.beginPath();
ctx.moveTo(mapX(35.0), mapY(1500)); // Bottom Left projected
ctx.lineTo(mapX(35.0), mapY(1950));
ctx.lineTo(mapX(41.0), mapY(2550));
ctx.lineTo(mapX(47.3), mapY(2550));
ctx.lineTo(mapX(47.3), mapY(1500));
ctx.closePath();
ctx.fill();
ctx.stroke();
// Draw Utility Category Polygon
ctx.fillStyle = "rgba(40, 167, 69, 0.2)";
ctx.strokeStyle = "#28a745";
ctx.beginPath();
ctx.moveTo(mapX(35.0), mapY(1500));
ctx.lineTo(mapX(35.0), mapY(1950));
ctx.lineTo(mapX(37.5), mapY(2200)); // Approx top left utility
ctx.lineTo(mapX(40.5), mapY(2200));
ctx.lineTo(mapX(40.5), mapY(1500));
ctx.closePath();
ctx.fill();
ctx.stroke();
// Draw Current Point
var px = mapX(currentCG);
var py = mapY(currentWeight);
ctx.beginPath();
ctx.arc(px, py, 6, 0, 2 * Math.PI);
ctx.fillStyle = "#dc3545";
ctx.fill();
ctx.strokeStyle = "white";
ctx.lineWidth = 2;
ctx.stroke();
// Add Labels
ctx.fillStyle = "#333";
ctx.font = "12px sans-serif";
ctx.fillText("Normal Category", mapX(42), mapY(2400));
ctx.fillStyle = "#1e7e34";
ctx.fillText("Utility", mapX(36), mapY(2100));
}
function resetCalculator() {
document.getElementById('basicEmptyWeight').value = "1663";
document.getElementById('emptyMomentArm').value = "39.6";
document.getElementById('frontPax').value = "340";
document.getElementById('rearPax').value = "0";
document.getElementById('baggage1').value = "0";
document.getElementById('baggage2').value = "0";
document.getElementById('fuelGallons').value = "53";
calculateWB();
}
function copyResults() {
var txt = "Cessna 172S Weight & Balance\n";
txt += "—————————-\n";
txt += "Total Weight: " + document.getElementById('resultWeight').innerText + "\n";
txt += "Total Moment: " + document.getElementById('resultMoment').innerText + "\n";
txt += "Center of Gravity: " + document.getElementById('resultCG').innerText + "\n";
txt += "Category Status: " + document.getElementById('resultStatus').innerText + "\n";
txt += "—————————-\n";
txt += "Load Details:\n";
txt += "Front: " + document.getElementById('frontPax').value + " lbs\n";
txt += "Rear: " + document.getElementById('rearPax').value + " lbs\n";
txt += "Fuel: " + document.getElementById('fuelGallons').value + " gal\n";
var temp = document.createElement("textarea");
temp.value = txt;
document.body.appendChild(temp);
temp.select();
document.execCommand("copy");
document.body.removeChild(temp);
var btn = document.querySelector('.btn-copy');
var originalText = btn.innerText;
btn.innerText = "Copied!";
setTimeout(function(){ btn.innerText = originalText; }, 2000);
}
// Initialize
window.onload = function() {
calculateWB();
// Resize listener for canvas
window.addEventListener('resize', function(){
var cg = parseFloat(document.getElementById('resultCG').innerText);
var w = parseFloat(document.getElementById('resultWeight').innerText);
drawChart(cg, w);
});
};