On the "10x" figure: Across multiple search strategies, no study, dataset, measurement, or even a wellness-industry article was located that states sand is ten times more powerful, ten times more conductive, or ten times more beneficial than grass. The number does not appear to originate from any identifiable source. There is also no established unit or endpoint by which "grounding power" is measured, so the multiplier has nothing to attach to.

On the physical mechanism: The claim's stated reason, that "the Earth's charge is stronger" on sand, misdescribes the physics. Earth's surface behaves as a conductor at effectively uniform potential; the fair-weather atmospheric field is on the order of 100 to 150 V/m and does not vary by ground cover in the way the claim implies. In fair weather the potential gradient at the ground is about 120V/m plus or minus 20 percent, with the earth negative with respect to the atmosphere . What genuinely differs between surfaces is electrical resistivity, not charge.

And resistivity runs against the claim. Engineering reference data shows low-resistance soils include clay and clay loam at roughly 80 to 100 ohm-metres, while the resistance of sand depends heavily on moisture content and ranges from 10 to 4,000 ohm-metres . Dry soil has high resistivity if it contains no soluble salts, and two thoroughly dried soil samples may in fact become very good insulators . Put plainly: dry beach sand is often a far worse conductor than moist grassy soil, not a better one. Even the pro-grounding wellness sites concede this. One states that dry sand does not conduct particularly well, but once it is wet, especially with saltwater, the conductivity becomes extremely strong .

On grounding health effects generally: The evidence base is small and contested. Cleveland Clinic notes that much of the existing research is of questionable quality, sometimes because sample sizes are too small to be meaningful, sometimes because of poor study design and sometimes because of flawed data analysis , and that a 2023 review argued most indoor-earthing experiments do not, and in some cases probably cannot, control for all the factors that influence biological grounding . Most grounding studies are small and rely somewhat on subjective measures such as self-reported effects or self-administered grounding therapy .

On the one real sand-versus-grass finding: There is a genuine, measured sand-versus-grass difference, but it is metabolic, not electrical. Pinnington and Dawson found that expressed as ratios of sand to grass running energy cost, barefoot sand running at 8 km/h gave 1.6 for net aerobic energy cost and 1.6 for net total energy cost; across all speeds combined the coefficients were 1.5 for net aerobic and 1.5 for net total energy cost, and sand running may provide a low impact but high energy cost training stimulus . Broader literature puts it similarly: walking is 1.8 to 2.7 times more energy-demanding on sand than on a hard surface, running is 1.2 to 1.6 times more costly, and jumping is 1.2 times more demanding on sand . Lejeune's team attributed the extra metabolic cost to work done on the sand and reduced efficiency in muscles and tendons, with one small laboratory study measuring a range of 2.1 to 2.7 times higher .

None of these numbers approach 10x, none concern electrical charge, and critically, all of them measure movement, not standing. The claim is about standing, where the metabolic advantage of sand largely evaporates.