  Let $E/\mathbb{Q}$ be a semistable elliptic curve such that
$\mathrm{ord}_{s=1}L(E,s) = 1$. We prove the $p$-part of the Birch and
Swinnerton-Dyer formula for $E/\mathbb{Q}$ for each prime $p \geq 5$ of good
reduction such that $E[p]$ is irreducible: $$ \mathrm{ord}_p \left
(\frac{L'(E,1)}{\Omega_E\cdot\mathrm{Reg}(E/\mathbb{Q})} \right ) =
\mathrm{ord}_p \left (\#\mathrm{Sha}(E/\mathbb{Q})\prod_{\ell\leq \infty}
c_\ell(E/\mathbb{Q}) \right ). $$ This formula also holds for $p=3$ provided
$a_p(E)=0$ if $E$ has supersingular reduction at $p$.
