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🔧 Pipe Calculator 2026

Calculate surface area, volume, capacity, and material weight of hollow pipes

Enter Pipe Dimensions

R r t
R = outer, r = inner, t = wall thickness

📊 Results

Outer Radius
5 cm
Inner Radius
4 cm
Wall Thickness
1 cm
Outer Surface
3,142 cm²
Inner Surface
2,513 cm²
Cross-Section
28.27 cm²
Material Vol
2,827 cm³
Inner Capacity
5,027 cm³
Material Weight
22.2 kg

📝 Key Formulas Applied

Outer Surface = 2πRL = 2π × 5 × 100 = 3,141.59 cm²
Inner Surface = 2πrL = 2π × 4 × 100 = 2,513.27 cm²
Material Volume = π(R² - r²)L = π(25-16)×100 = 2,827.43 cm³
Inner Capacity = πr²L = π × 16 × 100 = 5,026.55 cm³

📐 Pipe (Hollow Cylinder) Formulas

Outer Surface Area: Aout = 2πRL
Inner Surface Area: Ain = 2πrL
Cross-Section Area: Across = π(R² - r²)
Material Volume: Vmat = π(R² - r²)L
Inner Capacity: Vcap = πr²L
Weight: W = Vmat × density

Understanding Pipe Geometry

🔧 Hollow Cylinder

A pipe is a hollow cylinder. Has two radii: outer (R) and inner (r). Wall thickness t = R - r. All formulas involve both radii.

📏 Surface Areas

Outer: 2πRL. Inner: 2πrL. Plus two ring-shaped ends: 2π(R²-r²). Total = inner + outer + ends.

📦 Volumes

Material: π(R²-r²)L. Difference of two cylinders. Capacity: πr²L. The hollow space inside.

⚖️ Weight Calculation

Weight = Material Volume × Density. Common densities: Steel 7.85, Copper 8.96, Aluminum 2.7, PVC 1.4 g/cm³.

Frequently Asked Questions

What is the surface area formula for a pipe?
Total = 2πRL + 2πrL + 2π(R²-r²). Outer curved + inner curved + two ring ends. Often only lateral surfaces matter.
How do I calculate pipe volume?
Material volume = π(R² - r²)L. Or π(D² - d²)L/4 using diameters. Inner capacity = πr²L.
How do I find wall thickness?
t = R - r = (D - d)/2. Outer radius minus inner radius. Or half the difference of diameters.
How do I calculate pipe weight?
Weight = π(R² - r²) × L × density. Calculate material volume, multiply by density. Use consistent units (g/cm³ gives grams).
What is the inner capacity of a pipe?
V = πr²L. Same as cylinder volume using inner radius. This is how much fluid the pipe can hold.
How do I convert between diameter and radius?
Radius = Diameter / 2. Diameter = 2 × Radius. Be consistent — use either all radii or all diameters.
What is the cross-section area of a pipe?
A = π(R² - r²). The ring-shaped area. Also written as π(D² - d²)/4. Used for material calculations.
How much water can a pipe hold?
Volume = πr²L. Use inner radius. 1 liter = 1000 cm³. Example: r=2cm, L=100cm → 1,257 cm³ ≈ 1.26 liters.
What is nominal pipe size (NPS)?
Industry standard sizing. NPS doesn't equal actual diameter. NPS 2" pipe is ~2.375" OD. Always verify actual dimensions.
What is schedule in pipe sizing?
Wall thickness designation. Schedule 40, 80, etc. Higher schedule = thicker wall. Same NPS, different schedules have different wall thickness.
How do I calculate paint needed for a pipe?
Use outer surface area: 2πRL. Add end areas if painting ends. Divide by paint coverage (sq ft/gallon).
What is the weight of steel pipe per foot?
Depends on size and schedule. Use weight formula with steel density 7.85 g/cm³. Or use pipe weight tables for standard sizes.
How do I find inner diameter from outer and wall?
d = D - 2t. Inner diameter = outer diameter minus twice wall thickness. Wall thickness is on both sides.
What is the difference between pipe and tube?
Pipe: sized by NPS/ID (for flow). Tube: sized by exact OD (for structure). Different standards and tolerances.
How do I calculate flow capacity?
Flow rate depends on velocity and area. Q = A × v = πr² × velocity. This calculator gives cross-section; flow requires velocity.
What density should I use?
Common densities (g/cm³): Steel 7.85, Stainless 8.0, Copper 8.96, Aluminum 2.7, PVC 1.4, HDPE 0.95.
How accurate is this calculator?
Uses precise mathematical formulas. Accuracy depends on your input measurements. Real pipes may have manufacturing tolerances.