Jithin T JosephCTDS

Measurement-based placement guide

Translate head measurements into 10–20 scalp landmarks.

Enter scalp measurements, choose a placement system, then copy the selected point’s marking coordinates.

02

Choose method & scalp position

Anterior is shown at the top
Interactive top view of EEG scalp positionsSelect an electrode label to view calculated proportional placement guidance and approximate cortical orientation.NASIONINIONLEFTRIGHTFpzFp1Fp2F7F3FzF4F8T7C3CzC4T8P7P3PzP4P8O1O2Oz
STEP 2 · SCALP MARKINGContinue to device and coil positioning setup
Next: TMS positioning setup →

Scalp position is not source localisation. EEG electrodes record spatially mixed, volume-conducted activity. Cortical labels here are broad anatomical orientation—not a claim that a channel uniquely measures that brain region.

Method & measurement

Built around proportional scalp arcs.

The 10–20 system uses 10% offsets from anatomical landmarks and 20% intervals between major positions. Cz is established where the nasion–inion and left–right preauricular 50% marks intersect.

Reference basisIFCN standardized EEG electrode array · 2017 ↗Jurcak et al. · proportional systems validation ↗Beam et al. · Beam F3 original method · 2009 ↗Mir-Moghtadaei et al. · adjusted Beam F3 · 2015 ↗Fabregat-Sanjuan et al. · Beam F3 evaluation · 2022 ↗Recent geometric validation of Beam F3 methods · 2026 ↗
How to measure accurately +
  1. Use a flexible, non-stretch measuring tape held against the scalp.
  2. Identify the nasion, inion, and left/right preauricular points by palpation.
  3. Measure over the scalp surface—not as a straight line through space.
  4. Recheck Cz from both arcs before constructing the remaining rows.
What the three inputs can locate +

They directly scale the midline, central transverse arc, and outer circumference. F3/F4 and P3/P4 require secondary scalp-arc measurements between already marked positions; this tool identifies the midpoint rule but cannot infer those extra arc lengths.

Clinical use and limitations +

Use this calculator as a measurement aid and teaching tool. Clinical EEG setup should follow local laboratory procedures, current nomenclature, device instructions, and qualified neurodiagnostic supervision. Individual anatomy varies.