What is percent crystallinity?

Percent crystallinity is the fraction of a semi-crystalline polymer sample that exists in an ordered (crystalline) state, expressed as a percentage. It affects mechanical stiffness, barrier properties, and optical clarity.

Why do I need to subtract the cold-crystallization enthalpy?

During a DSC scan the sample may partially crystallize before melting (cold-crystallization exotherm). This artificially reduces the measured melt enthalpy, so the cold-crystallization enthalpy must be subtracted: % Xc = (ΔHm − ΔHcc) / ΔH°m × 100.

Where do I find the reference enthalpy (ΔH°m)?

Reference enthalpies for 100% crystalline polymers are published in the Polymer Handbook and scientific literature. Common values: PE = 293 J/g, PET = 140 J/g, PEEK = 130 J/g, Nylon 6 = 190 J/g, iPP = 209 J/g.

Can crystallinity exceed 100%?

No. If your result is above 100%, either the reference enthalpy you entered is too low for your specific polymer grade, or there is a measurement error in your DSC data. Check your peak integration and the reference value.

What units should I use?

All enthalpy values must be in the same units — typically J/g (joules per gram). Some older literature uses cal/g; multiply by 4.184 to convert to J/g.

Crystallinity Percent Calculator

Name: Crystallinity Percent Calculator
Availability: InStock
Author: Nham Vu

Enter your DSC heat of fusion values to instantly calculate polymer percent crystallinity.

DSC Input Values

Polymer Preset (auto-fills ΔH°m)

Measured Heat of Fusion, ΔH_m (J/g)

Area under the DSC melting endotherm (positive value).

Cold-Crystallization Enthalpy, ΔH_cc (J/g) (optional)

Area of the cold-crystallization exotherm (if present). Leave blank or 0 if none.

Reference Enthalpy, ΔH°_m (J/g)

Theoretical enthalpy of 100% crystalline polymer. Use the preset above or enter manually.

Percent Crystallinity

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Enter values and click Calculate

0% 100%

Formula Used

% X_c = (ΔH_m − ΔH_cc) / ΔH°_m × 100

Summary

Enter your DSC heat of fusion values to instantly calculate polymer percent crystallinity.

How it works

Enter the measured heat of fusion (ΔHm) from your DSC melting peak in J/g.
Optionally enter the cold-crystallization enthalpy (ΔHcc) to correct for any crystallization that occurred during the DSC scan.
Enter the reference enthalpy (ΔH°m) for a 100% crystalline sample of your polymer (e.g. 293 J/g for PET, 209 J/g for PEEK).
Click Calculate to get the percent crystallinity.
Use the preset dropdown to auto-fill common polymer reference values.

Use cases

Characterize crystallinity of PET, PEEK, nylon, polyethylene, and other semi-crystalline polymers.
Quality-control DSC measurements for polymer film or fiber production.
Compare crystallinity before and after annealing or processing treatments.
Academic and industrial research on polymer morphology.
Validate processing conditions for injection-molded parts.
Teaching DSC data analysis in polymer science courses.

Frequently Asked Questions

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Last updated: 2026-05-28 · Reviewed by Nham Vu