Calculate melt flow index (MFR) in g/10 min from extrudate mass and collection time, or solve for required mass or time with optional test conditions.

For multiple cutoffs, use total mass and total collection time from the same set.

Mass/time arithmetic only. Temperature and load are reported, not corrected; this does not certify an ISO or ASTM test.

Reported test conditions

kg denotes load mass; force conversion assumes standard gravity, 9.80665 m/s².

Related Calculators

Melt Flow Index Formula

The following formula is used to calculate the Melt Flow Index (MFI):

MFI = (M / T) × 10

Variables:

  • MFI is the Melt Flow Index (grams per 10 minutes)
  • M is the mass of the material extruded (grams)
  • T is the time taken for the extrusion (minutes)

To calculate the Melt Flow Index, divide the mass of the material extruded by the time taken for the extrusion and then multiply by 10 to get the index in grams per 10 minutes.

What is Melt Flow Index?

Melt Flow Index (MFI), also called melt mass-flow rate (MFR), describes thermoplastic mass flow under specified temperature, load and test conditions. Compare compatible materials using the same conditions and procedure. Within comparable tests, a higher MFR often indicates easier flow, but MFR is not a general viscosity measurement or a direct prediction of injection-molding performance. This calculator reports entered conditions without correcting results between conditions or certifying compliance with ISO 1133 or ASTM D1238.

How to Calculate Melt Flow Index?

The following steps outline how to calculate the Melt Flow Index (MFI).

  1. First, determine the mass of the material extruded (M) in grams.
  2. Next, determine the time taken for the extrusion (T) in minutes.
  3. Use the formula MFI = (M / T) * 10 to calculate the Melt Flow Index.
  4. Finally, enter the values into the calculator above to verify the result.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Mass of the material extruded (M) = 12 grams

Time taken for the extrusion (T) = 2 minutes