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Belt Roll Length Calculator

Calculate Total Belt Length from Roll Dimensions

Inventory management tool to determine how much belt is on a roll/spool

Roll Measurements
in
Total diameter of wound belt
in
Spool/core diameter
in
Thickness of belt material
in
Width of the belt
24
Number of Wraps/Coils on Roll
Roll Cross-Section Diagram

📏 How It Works

The formula calculates belt length by comparing the cross-sectional area of the wound belt (an annulus/ring shape) to the equivalent rectangular area if the belt were laid flat.

Cross-section area = π(D² - d²)/4 = Length × Thickness

Calculated Results
Total Belt Length
75.4
feet
904.8 inches
Belt Area
226
sq ft
Length × Width
Number of Wraps
24
coils
(D - d) / (2 × T)
Belt Material Volume
0.98
cu ft
Area × Thickness

Roll Length Formula

L = π(D² - d²) / (4T)
L = Belt Length  |  D = Outer Diameter (24")  |  d = Inner Diameter (6")  |  T = Belt Thickness (0.375")
Job Requirements Check

Check if you have enough belt for a specific job:

ft
Available: 75.4 ft  |  Required (with margin): 55.0 ft  |  Remaining: 20.4 ft
✓ SUFFICIENT
How to Measure
1
Measure Outer Diameter (D)
Measure across the full width of the wound belt roll at its widest point. Use a tape measure or caliper.
2
Measure Core Diameter (d)
Measure the inside diameter of the spool/core that the belt is wound on. This is the empty center hole.
3
Measure Belt Thickness (T)
Use calipers to measure the thickness of the belt material itself. Check manufacturer specs if available.

💡 Tips for Accurate Measurements

  • Outer Diameter: Measure in multiple places and average if the roll isn't perfectly round
  • Belt Thickness: Measure the actual belt, not including any protective covering
  • Compression: Tightly wound belts may have compressed layers - actual length may be slightly more
  • Belt Stretch: Rubber belts may have slight variations - allow 5-10% margin for jobs
Reverse Calculator - Find Outer Diameter

If you know the belt length you need, calculate the required roll outer diameter:

ft
in
in
in
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