Heat Exchanger, Coil & Radiator Manufacturing worked example

Fin Density with fins counted across the gauge length of 250 fins: a worked example

Push fins counted across the gauge length up to 250 fins and the picture changes. This example computes every intermediate figure at that operating point. Use it when a coil drawing, fin press setup, or supplier sample needs to be checked against the specified fins per inch or fins per meter.

The inputs for this scenario

  • Fins counted across the gauge length: 250 fins (raised for this scenario; the documented default is 100)
  • Inverse of measured core length (1 / inches): 0.25 1 / in (unchanged)
  • Inspection or unit conversion factor: 1 x (unchanged)
  • Usable fin fraction after damage/missing fins: 1 x (unchanged)

Working through the calculation

  • Applying the documented formula (Effective fin density = counted fins × inverse measured core length × inspection conversion factor × usable fin multiplier) to the inputs above produces each figure below.
  • At this operating point the engine returns 62.5 fins / in for effective fin density, the number this scenario is built around.
  • At this operating point the engine returns 62.5 value for raw fin density basis.
  • At this operating point the engine returns 1 x for usable fin multiplier.
  • At this operating point the engine returns 62.5 value for factor a x b.

How this compares with the baseline

  • Against the tool's baseline example, where fins counted across the gauge length sits at 100 fins and the headline result is 25 fins / in, this scenario comes in 150% above the baseline at 62.5 fins / in.
  • It computes effective fins per inch from a counted fin sample over a measured length, with optional multipliers for inspection derating, unit conversion or usable-fin scaling. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Effective fin density: 62.5 fins / in (headline result)
  • Raw fin density basis: 62.5 value
  • Usable fin multiplier: 1 x
  • Factor A x B: 62.5 value

Run it with your numbers

  • Every input above is editable in the live Fin Density calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.