🛫 How Many Ping-Pong Balls Can Fit in a Boeing 747? [Explained with Math!]

😕 Why This Question Even Exists

This quirky question is often used in tech job interviews (think: Google, Microsoft) to test your problem-solving skills, not your aviation knowledge. But hey, it’s also become a wildly popular internet riddle—so let’s break it down with actual logic.

🧠 Spoiler alert: it’s not just “a lot.” It’s millions—and we’re about to prove it.

✈️ Step-by-Step Calculation

Step 1: Find the Volume of a Boeing 747

We’ll use the Boeing 747-400 for this example. Here’s a basic estimation:

• Total interior volume (passenger + cargo): ~876 m³

• That’s 876,000,000 cm³ (since 1 m³ = 1,000,000 cm³)

Step 2: Volume of a Ping-Pong Ball

A standard ping-pong ball has:

• Diameter: 40 mm = 4 cm

• Radius: 2 cm

• Volume of a sphere: $V=\frac{4}{3}\pi r^{3}V\; =\; \backslash frac\{4\}\{3\}\; \backslash pi\; r^3$V=34​πr3

So:

$V=\frac{4}{3}\times 3.14\times 2^3=\frac{4}{3}\times 3.14\times 8\approx 33.53^{}V\; =\; \backslash frac\{4\}\{3\}\; \backslash times\; 3.14\; \backslash times\; 2^3\; =\; \backslash frac\{4\}\{3\}\; \backslash times\; 3.14\; \backslash times\; 8\; \approx \; 33.5\; \backslash text\{\; cm\}^3$V=34​×3.14×23=34​×3.14×8≈33.5 cm3

Step 3: Divide 747 Volume by Ball Volume

$\frac{876,000,000}{33.5}\approx 26,119,403 balls\backslash frac\{876,000,000\}\{33.5\}\; \approx \; 26,119,403\; \backslash text\{\; balls\}$33.5876,000,000​≈26,119,403 balls

But wait—we’re not done yet.

⚠️ Real-World Adjustment: Packing Efficiency

You can’t pack spheres perfectly. There’s always wasted space between them. For spheres, maximum packing efficiency is about 74% (close-packing of spheres in 3D).

So, we adjust:

$26,119,403\times 0.74\approx \boxed{{\displaystyle 19,329,358 ping-pong balls}}26,119,403\; \backslash times\; 0.74\; \approx \; \backslash boxed\{19,329,358\; \backslash text\{\; ping-pong\; balls\}\}$26,119,403×0.74≈19,329,358 ping-pong balls​

🎯 Final Answer: Approximately 19.3 million ping-pong balls can fit inside a Boeing 747.

🤯 Fun Follow-Ups

• How much would it weigh?
  One ping-pong ball = ~2.7 grams
  So:

  $19,329,358\times 2.7g\approx 52,590kg19,329,358\; \backslash times\; 2.7g\; \approx \; 52,590\; kg$19,329,358×2.7g≈52,590kg

  That’s over 50 tons of lightweight plastic!

• Would it fly?
  A fully loaded 747 can handle ~440,000 kg. So yes, technically it could fly full of ping-pong balls!