How do I calculate the right amount of pool shock?

Multiply length × width × average depth × 7.5 to get gallons. Average depth is (shallow end + deep end) / 2. Then read the shock label for dose per 10,000 gallons — most granular shocks need 1 pound per 10,000 gallons to raise chlorine 10 ppm. Test your water first to avoid over- or under-shocking.