For single-walled carbon nanotubes (SWCNTs), given the known product of the Young's modulus Y and the wall (bond) thickness t (Yt congruent to 0.3685 TPa.nm) and the known temperature of tip-end melting (T-m = 1593 K), as well as their functional dependence on atomic coordination and bonding energy, the dimension and strength of a C-C bond in a SWCNT have been determined. The uniqueness of the solution reveals that the C-C bond (or the wall of the SWCNT) is similar to0.142 nm thick and similar to0.125 nm long (an 18.5% contraction of diamond bond length, 0.154 nm), with a 68% increase in binding energy, with respect to the bulk graphite values. Therefore, the measured Yt and T-m values essentially represent the true SWCNT situation.