DEM GRID & FILE SIZE

Spacing Units   X-Pts Y-Pts Total Elevations MB
1 m   86400 111000 9,590,400,000 18,292 (18 GB)
10 m   8640 11100 95,904,000 182.92
20 m   4320 5550 23,976,000 45.73
30 m   2880 3700 10,656,000 20.32
50 m   1728 2220 3836160 7.32
100 m   864 1110 959040 1.83
250 m   346 444 153624 0.29
1/27 " ~1m 97,201 97,201 9,448,034,401 18,020
1/9 " ~3m 32,401 32,401 1,049,824,801 2002
1/3 " ~10 m 10,801 10,801 116,661,601 222.5
1 " ~30 m 3601 3601 12,967,201 24.73
3 " ~90m 1201 1201 1,442,401 2.75
30 " ~1 km 121 121 14,641 0.03
5 ' ~10 km 13 13 169 0.00

The number of points to cover a one degree square at the latitude of Annapolis, MD (39ºN). This assumes 2 byte integers for the elevations; most newer DEMs, especially those at higher resolution, use 4 byte reals, which would double the size of the DEM. These values also do not include any headers or metadata, which are typically a tiny fraction of the file size.

The values for spacing in geographic coordinates would not vary with latitude, while DEMs with spacing in meters will get smaller with latitude.

Actual file sizes depend on the size of the region covered by the DEM and the resolution.

Approximate metric equivalents


Last Updated on 12/4/2015