This study provides the first global estimates of fine root biomass, length, surface area, and nutrient contents, along with their depth distribution in the soil. Fine roots (≤2 mm in diameter) are crucial for water and nutrient uptake by plants, similar to how leaves contribute to carbon and energy uptake. They are also a major sink for carbon from terrestrial net primary productivity. Despite their importance, fine roots are poorly represented in global models, unlike leaf area data, which are widely available. The analysis uses data from 253 field studies to estimate global fine root distributions. It calculates root surface area, which is often greater than leaf area, especially in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of atmospheric carbon. Assuming fine roots turnover once per year, they represent 33% of global annual net primary productivity. The study provides global estimates of fine root biomass, length, surface area, and nutrient contents. These data can enhance hydrological models, improve estimates of nitrogen cycling, and allow biochemical modeling of nutrient uptake globally. The results show that fine root biomass varies widely across biomes, with temperate grasslands having the highest values. Live fine root biomass is significant, with surface area four times that of Earth and 14 times the total land surface area. The study highlights the importance of fine roots in nutrient cycling, carbon allocation, and global biogeochemistry. It also notes the challenges in estimating root distributions and the need for more data to refine models. The findings suggest that fine roots are disproportionately important for estimating annual net primary production, nutrient cycling, and carbon allocation due to their small size, short lifespan, and high turnover rate. The study provides a benchmark for future research and model improvements.This study provides the first global estimates of fine root biomass, length, surface area, and nutrient contents, along with their depth distribution in the soil. Fine roots (≤2 mm in diameter) are crucial for water and nutrient uptake by plants, similar to how leaves contribute to carbon and energy uptake. They are also a major sink for carbon from terrestrial net primary productivity. Despite their importance, fine roots are poorly represented in global models, unlike leaf area data, which are widely available. The analysis uses data from 253 field studies to estimate global fine root distributions. It calculates root surface area, which is often greater than leaf area, especially in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of atmospheric carbon. Assuming fine roots turnover once per year, they represent 33% of global annual net primary productivity. The study provides global estimates of fine root biomass, length, surface area, and nutrient contents. These data can enhance hydrological models, improve estimates of nitrogen cycling, and allow biochemical modeling of nutrient uptake globally. The results show that fine root biomass varies widely across biomes, with temperate grasslands having the highest values. Live fine root biomass is significant, with surface area four times that of Earth and 14 times the total land surface area. The study highlights the importance of fine roots in nutrient cycling, carbon allocation, and global biogeochemistry. It also notes the challenges in estimating root distributions and the need for more data to refine models. The findings suggest that fine roots are disproportionately important for estimating annual net primary production, nutrient cycling, and carbon allocation due to their small size, short lifespan, and high turnover rate. The study provides a benchmark for future research and model improvements.