This spell causes instant growth of humanoid creatures, doubling its height and multiplying its weight by 8. This increase changes the creatures's size category to the next larger one. The target gains a +2 size bonus to Strength, a –2 size penalty to Dexterity (to a minimum of 1), and a –1 penalty on attack rolls and AC due to its increased size.a

Humanoid creatures whose size increase to Large have a space of 10 feet and a natural reach of 10 feet. This spell does not change the target's speed.

If insufficient room is available for the desired growth, the creatures attain the maximum possible size and may make a Strength check (using its increased Strength) to burst any enclosures in the process. If it fails, it is constrained without harm by the materials enclosing it—the spell cannot be used to crush creatures by increasing its size.

All equipment worn or carried by creatures are similarly enlarged by the spell. Melee weapons affected by this spell deal more damage (see Table: Tiny and Large Weapon Damage). Other magical properties are not affected by this spell. Any enlarged item that leaves an enlarged creatures's possession (including a projectile or thrown weapon) instantly returns to its normal size. This means that thrown and projectile weapons deal their normal damage. Magical properties of enlarged items are not increased by this spell.

Multiple magical effects that increase size do not stack.

Mass Enlarge person counters and dispels mass reduce person.

Mass enlarge person can be made permanent with a permanency spell.