Panel for covering a surface of a room, comprising a panel element extending in a longitudinal direction and in a transverse direction for transferring use loads introduced at an upper side of the panel element to a lower side of the panel element facing the surface of the room, wherein the upper surface is spaced apart from the lower side in a thickness direction, with a nominal width B of the panel element between a first edge extending in the longitudinal direction and a second edge of the panel body 28 extending in the longitudinal direction, a retaining groove extending in an end face short side of the panel element in the transverse direction with an extension b 0 in the transverse direction; and a locking element inserted into the retaining groove, in particular immovably, wherein the panel element comprises at the first edge a bung groove extending into the panel element and at the second edge a bung projection projecting from the panel element, wherein a first reinforcing area with an extension t 1 in the transverse direction is formed between a first end of the retaining groove facing the first edge in the transverse direction, wherein the reinforcing area is free of the retaining groove, wherein a second reinforcing area with an extension t 2 in the transverse direction is formed in the transverse direction between a second end of the retaining groove facing the second edge in the transverse direction, wherein the reinforcing area is free of the retaining groove, with the proviso that t 1 + b 0 + t 2 = B, characterized in that for the extension b 0 of the retaining groove in the transverse direction with respect to the nominal width B of the panel element 0.50 ≤ b 0 /B ≤ 0.97, in particular 0.75 ≤ b 0 /B ≤ 0.95, preferably 0.85 ≤ b 0 /B ≤ 0.93 and particularly preferably b 0 /B = 0.90 ± 0.02 applies, wherein for the first reinforcing area 0.005 ≤ t 1 /B ≤ 0.090, in particular 0.015 ≤ t 1 /B ≤ 0.050, preferably 0.020 ≤ t 1 /B ≤ 0.030 and particularly preferably t 1 /B = 0.025 ± 0.002 and/or for the second reinforcing region 0.005 ≤ t 2 /B ≤ 0.090, in particular 0.015 < t 2 /B < 0.050, preferably 0.020 ≤ t 2 /B ≤ 0.030 and particularly preferably t 2 /B = 0.025 ± 0.002 applies, and wherein t 1 < t 2, in particular 0.75 ≤ t 1 /t 2 ≤ 0.99, preferably 0.80 ≤ t 1 /t 2 ≤ 0.95 and particularly preferably 0.85 ≤ t 1 /t 2 ≤ 0.90 applies. a panel element extending in a longitudinal direction and in a transverse direction for transferring use loads introduced at an upper side of the panel element to a lower side of the panel element facing the surface of the room, wherein the upper surface is spaced apart from the lower side in a thickness direction, with a nominal width B of the panel element between a first edge extending in the longitudinal direction and a second edge of the panel body 28 extending in the longitudinal direction, a retaining groove extending in an end face short side of the panel element in the transverse direction with an extension b 0 in the transverse direction; and a locking element inserted into the retaining groove, in particular immovably, wherein the panel element comprises at the first edge a bung groove extending into the panel element and at the second edge a bung projection projecting from the panel element, wherein a first reinforcing area with an extension t 1 in the transverse direction is formed between a first end of the retaining groove facing the first edge in the transverse direction, wherein the reinforcing area is free of the retaining groove, wherein a second reinforcing area with an extension t 2 in the transverse direction is formed in the transverse direction between a second end of the retaining groove facing the second edge in the transverse direction, wherein the reinforcing area is free of the retaining groove, with the proviso that t 1 + b 0 + t 2 = B, characterized in that for the extension b 0 of the retaining groove in the transverse direction with respect to the nominal width B of the panel element 0.50 ≤ b 0 /B ≤ 0.97, in particular 0.75 ≤ b 0 /B ≤ 0.95, preferably 0.85 ≤ b 0 /B ≤ 0.93 and particularly preferably b 0 /B = 0.90 ± 0.02 applies, wherein for the first reinforcing area 0.005 ≤ t 1 /B ≤ 0.090, in particular 0.015 ≤ t 1 /B ≤ 0.050, preferably 0.020 ≤ t 1 /B ≤ 0.030 and particularly preferably t 1 /B = 0.025 ± 0.002 and/or for the second reinforcing region 0.005 ≤ t 2 /B ≤ 0.090, in particular 0.015 < t 2 /B < 0.050, preferably 0.020 ≤ t 2 /B ≤ 0.030 and particularly preferably t 2 /B = 0.025 ± 0.002 applies, and wherein t 1 < t 2, in particular 0.75 ≤ t 1 /t 2 ≤ 0.99, preferably 0.80 ≤ t 1 /t 2 ≤ 0.95 and particularly preferably 0.85 ≤ t 1 /t 2 ≤ 0.90 applies.