Cap Size Guide (Choosing the Right Fit)

Mentalab provides elastic EEG caps in multiple sizes to accommodate different head circumferences. Sizes may vary slightly depending on cap type (gel vs. dry), but the general ranges are:

Cap Size Head Circumference

Small (S)

52–54 cm

Medium (M)

54–58 cm

Large (L)

58–62 cm

Extra Large (XL)

62–64 cm

Always measure the participant’s head circumference just above the eyebrows and around the back of the head to determine the correct size.

Fitting Instructions

  • Measure the participant’s head circumference with a flexible tape measure.

  • Select the cap size corresponding to the measurement range.

  • Place the cap so that the Cz position (top center) aligns with the vertex of the head.

  • Adjust the chin strap or elastic fixation straps if provided.

  • Ensure that all electrode holders sit flush against the scalp.

Best Practices

  • The cap should fit snugly but not uncomfortably tight.

  • A well-fitting cap improves both participant comfort and electrode impedance.

  • For participants between sizes, choose the smaller cap for a tighter fit (better contact) and adjust with elastic straps.

  • Use the supplied elastic cap cover to further stabilize electrodes and minimize cable movement.

Special Considerations

  • Children and small head sizes: custom or pediatric caps may be required.

  • Hair type: thick or curly hair can make contact more difficult. In such cases, use gel electrodes or apply hair-parting techniques to improve signal quality.

  • Long recordings: check periodically that the cap remains in position and does not cause pressure points.