It is generally accepted that San Andreas is approximately 6 km x 6 km = 36 sq km
The real life LA forum is approximately 150 metres.
(original image was 1536 x 1536)
LS forum in San Andreas was approximately 40 pixels
The red line in above screenshot is 800 pixels = 3 km.
The red line is just over half the width of San Andreas.
This gives a surprisingly accurate estimate of the map size for SA.
(original image was 800 x 519)
LS forum in GTA V was approximately 30 pixels
The red line in above screenshot is 300 pixels = 1.5 km.
Is the LS forum in GTA V to scale as it was in SA or have they made it much larger for some reason?
If the LS forum was 2x the size of its real life counterpart the red line would be 3 km.The solution I come up with is as follows.
LS in San Andreas and LS in GTA V are both approximately 3 km wide.
However, the scale of GTA V is approximately 2x that of San Andreas. This explains why the forum is twice the size it is in San Andreas and also explains how the map can appear small but is actually "bigger than SA, RDR and IV combined".
So both versions of LS are 3 km wide, but LS in GTA V is twice as large in reality.