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The electronic bandwidth is the difference between the maximum and minimum of one energy band over the Brillouin zone. It has units of energy, unlike a frequency bandwidth in signal processing. A nearest-neighbour tight-binding model on a primitive cubic lattice with equal real hopping integrals $t$ has $E(\mathbf{k})=E_0+2t{\sum }_{i=1}^3\cos (k_{i}a)$ and $W=12|t|$.

The electronic bandwidth is $W(a)=24E_1{e}^{-a/a_1}$. With $a$ reduced from $a_1$ to $0.99a_1$,Thus the energy band widens by approximately 1.005 percent, or 1 percent to first order. Compression increases the orbital coupling.