Size/Reach questions

[KvotheComplex]

ok so maybe my group has just been doing this wrong all along but I thought I large creature taking up a 10ft space only occupies two 5 foot squares not 4 squares. The creature is also supposed to have a 10ft reach which I always understood to be the two squares behind it, in front of it, and to each side of it with two diagonal spaces being 15 foot not 10. That is to say I thought when moving diagonally it went 5ft then 15ft if you moved two diagonal spaces in a row. I am placing a creature with a 10ft space and 10ft reach on the map and it is taking up four squares and threatening the 10ft in front, behind, and on the sides but also threatening two diagonal squares on all sides.

[Kelrugem]

ok so maybe my group has just been doing this wrong all along but I thought I large creature taking up a 10ft space only occupies two 5 foot squares not 4 squares. The creature is also supposed to have a 10ft reach which I always understood to be the two squares behind it, in front of it, and to each side of it with two diagonal spaces being 15 foot not 10. That is to say I thought when moving diagonally it went 5ft then 15ft if you moved two diagonal spaces in a row. I am placing a creature with a 10ft space and 10ft reach on the map and it is taking up four squares and threatening the 10ft in front, behind, and on the sides but also threatening two diagonal squares on all sides.

Indeed, the space number is the length of the total square which it is occupying :) So, 10 ft. space is indeed 2x2 5ft. squares :)

For reach: Beware FG is not showing the correct reach, the reach is always drawn as a square which covers closely the normally-wanted "stretched circle" (so it draws a "stretched circle" in the so-called uniform norm :D). BUT: For 10 and 5 ft. the reach underlays are correct, the second diagonals are indeed 15 ft. but they are still covered by a 10 ft. reach. This does not hold anymore for bigger reaches, I mean you do not get additional diagonal squares there (though FG will still show the wrong square reach version), so the 10 ft. reach has some exceptional rule where 15 ft. diagonals count as 10 ft. :)

See more here: https://www.d20pfsrd.com/gamemastering/combat/space-reach-threatened-area-templates/