Free Plate Number Calculator
Calculate the number of theoretical plates (N) and plate height (HETP) for chromatographic column efficiency.
min
min
cm
Theoretical Plates (N)
25,600
Plate Height (HETP)0.00098 cm
Plate Height9.8 um
Theoretical Plates (N) vs Retention Time (tR)
Theoretical Plate Number
The plate count N measures column efficiency. Higher N means sharper peaks and better separation potential.
Formula
N = 16 × (tR / w)²
HETP = L / N
where w is the peak width at the base (4-sigma). Modern HPLC columns typically give N = 10,000-20,000 per 25 cm column. UHPLC with sub-2-um particles can achieve 30,000+ plates.
Example Calculation
A peak at 10 min with 0.25 min base width on a 25 cm column.
- 01N = 16 × (10 / 0.25)² = 16 × 40² = 16 × 1600 = 25,600 plates
- 02HETP = 25 / 25600 = 0.000977 cm = 9.8 um
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