Solar rings and blankets warm your pool and cut overnight heat loss. Figure out how many circular rings you need — accounting for the gaps circles leave, which simple area math misses — or the solid-blanket size.
Circular solar rings can't tile a rectangular pool without leaving gaps between them, so dividing pool area by ring area undercounts how many you need. This calculator applies a realistic packing factor — about 78%, because floating rings drift and overlap rather than sitting in a perfect lattice — and lets you pick a coverage target. Rings are designed for partial coverage; most people aim for around 70–80% of the surface, which captures most of the heat-retention benefit without fully tiling the pool. A solid blanket, by contrast, is simply cut to the pool's outline, so its size is just your surface dimensions.
A cover's main job is stopping evaporation, which is the biggest source of overnight heat loss — an uncovered pool can shed several degrees overnight, and a cover prevents most of that. But the exact degrees depend on air temperature, wind, humidity, and your water temperature on any given night, so no calculator can promise a specific number. For an honest look at the water and heating savings a cover provides over a season, use our pool cover savings calculator, which estimates the evaporation and dollars saved from your pool's surface area.
A 32 × 16 ft pool (512 sq ft) with 5 ft rings, targeting 75% coverage: each ring covers ≈ 19.6 sq ft × 78% packing, so about 26 rings — more than naive area division suggests, because of the gaps.