In most seismological centers a surface wave magnitude MS is determined using the “Prague formula” (MS = log10(A/T)max + 1.6log10(∆) + 3.3), whose adequacy was repeatedly discussed in publications. We checked the compliance of the calibration curve used in the “Prague formula” with attenuation of the surface waves in the wide period range T = 5–30 s depending on distance for Russian Far East earthquakes 2013–2018, h ≤ 50 km. For epicentral distances Δ= 2–80 degrees, a loglinear dependence of deviations dMS = MSst–MSav of station magnitudes MSst published in the Seismological Bulletin of the Geophysical Survey RAS (SB GS RAS) on the network average MSav is established: dMS = 0.608 log10 (∆)–0.95. It can be compensated for by adding a distance correction function δMSΔ=−dMS to the “Prague formula”. Using distance corrections can reduce the internal scatter of the MS scale by SB GS RAS from the standard deviation S0 = 0.379 of dMS values down to the residual standard deviation S = 0.306 taking into account the dependence of dMS on distance. The introduction of the corrections is especially necessary when the majority of station magnitudes MSst are obtained at short distances, which is typical for weak earthquakes with MS < 4. When analyzing macroseismic data from 34 earthquakes in Northern Eurasia, we also discovered a tendency of underestimation of the MSISC and MSMOS magnitudes of weak earthquakes compared to the magnitude MI which best satisfies the observed macroseismic effect from these earthquakes and the regional macroseismic field.