<p>Studies quantifying deadwood carbon (C) stocks are prone to major sources of errors owing to the use of generic conversion factors when converting deadwood biomass to C stocks (that is, wood “carbon fractions” [CFs]). Generally, studies assume that 50% of dead wood is comprised of elemental carbon, though analyses have shown this is a poor approximation of dead wood chemistry. We quantify the degree to which wood CFs influence our understanding of deadwood C stocks, by (1) estimating deadwood biomass from a complete inventory of 3,820 deadwood pieces in a 13.5&#xa0;ha temperate mixed-species forest and (2) integrating site- and species-specific wood CFs with deadwood biomass, to (A) estimate total deadwood C stocks, (B) assess the magnitude of errors which occur when generic wood CFs are used to estimate deadwood C stocks, and (C) quantify the volatile C stock, that is, the quantity of the overall C stock that is ‘lost’ or unaccounted for when studies employ wood CFs that do not include volatile C compounds (also called the “VCF”). Deadwood accounted for 13.42&#xa0;Mg of C ha⁻¹, with the VCF accounting for ~4% of total deadwood C stocks. A 50% wood CF underestimated forest-scale C stocks by ~ 3.6%, with these errors increasing over larger spatial scales. Our work contributes both a better understanding of how dead wood chemical traits of individual trees scale-up to influence rates of ecosystem functioning, alongside insights into the role volatile compounds play in forest chemical ecology.</p>