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The fraction of ionizing photons that escape high-redshift galaxiessensitively determines whether galaxies reionized the early universe. However,this escape fraction cannot be measured from high-redshift galaxies because theopacity of the intergalactic medium is large at high redshifts. Without methodsto indirectly measure the escape fraction of high-redshift galaxies, it isunlikely that we will know what reionized the universe. Here, we analyze thefar-ultraviolet (UV) H I (Lyman series) and low-ionization metal absorptionlines of nine low-redshift, confirmed Lyman continuum emitting galaxies. We usethe H I covering fractions, column densities, and dust attenuations measured ina companion paper to predict the escape fraction of ionizing photons. We findgood agreement between the predicted and observed Lyman continuum escapefractions (within $1.4\sigma$) using both the H I and ISM absorption lines. Theionizing photons escape through holes in the H I, but we show that dustattenuation reduces the fraction of photons that escape galaxies. This meansthat the average high-redshift galaxy likely emits more ionizing photons thanlow-redshift galaxies. Two other indirect methods accurately predict the escapefractions: the Ly$\alpha$ escape fraction and the optical [O III]/[O II] fluxratio. We use these indirect methods to predict the escape fraction of a sampleof 21 galaxies with rest-frame UV spectra but without Lyman continuumobservations. Many of these galaxies have low escape fractions ($f_{\rm esc}\le 1$\%), but 11 have escape fractions $>1$\%. The methods presented here willmeasure the escape fractions of high-redshift galaxies, enabling futuretelescopes to determine whether star-forming galaxies reionized the earlyuniverse.

Accurately predicting the escape fraction of ionizing photons using restframe ultraviolet absorption lines