Roll Length Calculator
Length of material on a roll from its outside and core diameters, with the number of turns, area and weight.
Results
Length
7808.617
m
Turns on the roll
4620.0
Area
7808.62
m²
Mass
624.689
kg
Roll outside diameter
364.83
mm
What this tool does
The formula works by comparing areas: the ring of material seen from the end, divided by the thickness, is the length unwound. It applies to any wound web — paper, film, foil, tape, label stock. Measure the diameter with a tape around the roll and divide by pi if callipers will not reach, and remember that a wound roll is always a little looser than the nominal thickness suggests.
Formula
L = π (D² − d²) ÷ (4 t)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
dd | Roll outside diameter | mm |
dc | Core diameter | mm |
th | Material thickness | mm |
wd | Width | mm |
gs | Grammage | g/m² |
LM | Length | m |
TU | Turns on the roll | — |
M2 | Area | m² |
KG | Mass | kg |
DR | Roll outside diameter | mm |
Worked example
- Roll outside diameter1000 mm
- Core diameter76 mm
- Material thickness0.1 mm
- Width1000 mm
- Grammage80 g/m²
- Length7808.617 m
- Turns on the roll4620.0
- Area7808.62 m²
- Mass624.689 kg
- Roll outside diameter364.83 mm
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- Coverage and consumption figures vary between products. Take the values from the manufacturer's datasheet for the product you are actually using.
- The calculation runs at full precision and only the display is rounded. If you copy an intermediate value and retype it, small differences can appear.