Let $X$ be an $n$-dimensional proper algebraic variety over $K$ and $\mathfrak{X}$ a strongly nondegenerate polystable formal model of $X^{\textup{an}}$ over $K^{\circ}$ with associated skeleton $\Delta$. Let $\tau$ be an $n$-dimensional open face of $\Delta$ with associated point $S$ in the special fibre of $\mathfrak{X}$. Let $h$ be a convex function on $\tau$ and denote by $\overline{\mathcal{O}}^{h\circ p_{\mathfrak{X}}}$ the trivial line bundle on the strictly $K$-analytic space $p_{\mathfrak{X}}^{-1}(\tau)$ endowed with the metric given by $\|1\|=e^{-h\circ p_{\mathfrak{X}}}$. Then

$$c_{1}\left(\overline{\mathcal{O}}^{h\circ p_{\mathfrak{X}}}\right)^{n}=[\tilde{K}(S):\tilde{K}]\cdot n!\cdot\MA(h)$$

on $p_{\mathfrak{X}}^{-1}(\tau)$.