This paper examines the sources of uncertainty for the Forced Diffusion (FD) chamber soil respiration (Rs) measurement technique, and demonstrates a protocol for uncertainty quantification that could be appropriate with any soil flux technique. Here, we sought to quantify and compare the three primary sources of uncertainty in Rs: (1) instrumentation error, (2) scaling error, which stems from the spatial variability of Rs , and (3) random error, which arises from stochastic or unpredictable variation in environmental drivers, and was quantified from repeated observations under a narrow temperature, moisture, and time range. In laboratory studies, we found that FD instrumentation error remained constant as Rs increased. In field studies from five North American ecosystems, we found that as Rs increased from winter to peak growing season, random error increased linearly with average flux by about 40% of average Rs. Random error not only scales with soil flux, but scales in a consistent way (same slope) across ecosystems. Scaling error, measured at one site, similarly increased linearly with average Rs, by about 50% of average Rs. Our findings are consistent with previous findings for both soil fluxes and eddy covariance fluxes across other Northern temperate ecosystems that showed random error scales linearly with flux magnitude with a slope of ~0.2. Although the mechanistic basis for this scaling of random error is unknown, it is suggestive of a broadly applicable rule for predicting flux random error. Also consistent with previous studies, we found the random error of FD follows a Laplace (double-exponential) rather than a normal (Gaussian) distribution.