The glass funnel for a cathode ray tube includes a cylindrical funnel neck (2); a funnel body (4) having successive transverse cross-sections that change over from a substantially circular shape to a substantially rectangular shape with cross-sectional areas growing continuously in a direction moving away from the funnel neck and a parabolic region (3) arranged between the funnel neck and the funnel body and having respective connecting sections to the funnel neck and the funnel body having corresponding substantially circular cross-sections. The parabolic region (3) has at least one part with a substantially rectangular cross-section and the at least one part is located between the respective connecting sections to the funnel neck and the funnel body. When a cathode ray tube is made from the glass funnel the electron gun is located in the funnel neck and the deflecting coil is arranged around to the parabolic section so that it is substantially closer than in the prior art cathode ray tube. The glass funnel described herein thus provides energy savings and a more precise electron beam guidance than the corresponding prior art glass funnel, when it is incorporated in a cathode ray tube.