The perimeter of a pool that is EXACTLY 15' wide by 30' long is 77'1". You have to be careful though as a lot of pools are not made exactly to those specs. Often they are a little bit smaller which effects the perimeter a lot.
A 15 by 30 foot swimming pool can be any depth. As a constructor of gunite or concrete pools I could make any size of pool any depth from 6 inches to 10 feet or more. The size of a pool has no direct effect on the depth. We did pools for exercising horses that were 10 feet deep for the entire pool. A pool of any size for normal use will have a shallow end, usually 2 and 1/2 to 3 feet in depth and will graduate to 6 feet for swimming or 8 or more feet in depth for diving. With fiberglass or vinyl liner pools the depths are established by the manufacturer and you will have to choose from the sizes offered what will best suit your needs. I believe some of the manufacturers may make custom sizes per the purchasers request, but the price will be significantly higher for a special order.
4500 US Gallons
20,500 gallons
15' x 24' oval pool with 54" wall has 8,823 gallons of water.
Approximately 12,000 gallons.
If its an oval pool approx 7800 gallons at full capacity. If its rectangular pool then approx 9000 Gallons.
formula for determining how many gallons in a pool is, length times width times average depth times 7.5 = gallons of water in pool if it round or oval its times 5.9
a lot
If rectangular about 21,000 gallons if oval about 16,000 gallons
http://www.havuz.org/pool-calculators.htm try this link
What are your depths in the deep and shallow end and what shape is the pool? Rectangular, kidney, oval or irregular?
How large is the pool? In ground or above ground? Shape? Above ground is easier to calculate. I have an oval above ground pool which is 18 x 38. It holds approx. 15,000 gallons. To get an accurate answer, you need to be far more specific.