Regression relationships are derived relating the areal extent of large distributive fluvial systems (DFSs) (> 30 km in length) formed in endorheic basins to contributing drainage area. The resulting correlation coefficients vary between 79% and 98%. Derived correlation values are strikingly similar when stratified by climate, large-scale tectonic regime, and basin context. Regression-equation exponent values range from 0.41 to 0.75, indicating a strong positive relationship between drainage area and DFS area, while coefficients account for the influence of external parameters on the derived relationships. Analysis of the dataset using planform morphology and drainage-basin slope as additional variables reveals that regressions for braided bifurcating DFS produce a highly significant relationship. The relationship suggests that drainage-basin relief influences sediment supply to the sedimentary basin in terms of volume or caliber, which in turn affects the depositional gradient of the DFS surface and resultant channel planform. An evaluation of the predictive capability of the regression equations reveals that the relationships derived from braided bifurcating DFSs perform best, with 80% of the predicted values falling within ± 25% of the measured DFS area value, with a third of the predicted values within ± 10% of the measured DFS area value. Application of the regression relationships derived here to rock-record examples of fluvial deposits interpreted as large DFSs show that DFS area can be used as a proxy to predict the surface area of fluvially transported sediment deposited in a sedimentary basin from the contributing drainage-basin area. The regression relationships for modern drainage areas and corresponding DFS areas from a range of tectonic and climatic settings suggest a measurable link between source and sink in the sedimentary rock record. The results provide a potential tool for more accurate reconstruction and prediction of preserved fluvial deposits and basin-fill architecture within basin-scale climatic and tectonic contexts.