In order to figure out the correct amount of chemicals to add to your pool, first you have to know how much water your pool can hold. Begin by calculating your pool's depth, then you can determine capacity by using one of the formulas from this chart:

AVERAGE DEPTH = SHALLOW END DEPTH + DEEP END DEPTH % 2

RECTANGLE POOLS: length x width x average depth x 7.5 = *total gallons	ROUND POOLS: circular diameter x diameter x average depth x 5.9 = *total gallons
OVAL POOLS: full width x full length x average depth x 5.9 = *total gallons	SLOPING SIDES: if your pool has sloping sides, multiply the final figure by .85.