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). Those newly formed crystals also melt during the endotherm, artificially inflating the measured melting enthalpy (ΔHm) relative to the initial crystalline state, so ΔHcc 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

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

This tool calculates the percent crystallinity of a polymer sample using differential scanning calorimetry (DSC) data. You provide the measured heat of fusion from your DSC thermogram and the theoretical heat of fusion for a 100% crystalline reference, and the calculator returns the crystallinity percentage. An optional correction for residual crystallinity after a cold-crystallization event is also supported.

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. 140 J/g for PET, 130 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

Last updated: 2026-09-30 · Reviewed by Nham Vu