How Much Does a Pool Blanket Save? The Real Math
"How much does a pool blanket actually save?" is one of the most asked questions in residential pool ownership — and the most ducked. Manufacturers quote vague "up to 70% savings" numbers; pool stores recommend a cover and move on. Neither tells you the specifics: how much in dollars, on what timeline, and whether the cover pays for itself before it wears out.
This guide walks through the math with real numbers for a 20×40 inground pool. If you have different dimensions or live in a different climate, the same percentages apply — just adjust the gallon counts and gas costs.
In this guide
The three savings categories
A solar blanket saves money in three independent ways. They all add up, but you need to count each one separately to understand the real number.
- Heat retention — less BTUs lost overnight means less gas, less heat-pump electricity, or longer swim season at the same fuel cost.
- Water evaporation — less refill water means lower water bills and less stress on your well or municipal supply.
- Chemical retention — evaporated water takes chlorine, stabilizer, and pH chemicals with it. A cover keeps them in the pool.
Let's break each one down.
Heat retention savings (the big one)
An uncovered pool loses heat overnight through four paths: evaporation (about 70% of total nighttime loss), radiation to cold sky (about 20%), convection (about 8%), and conduction to the surrounding ground (about 2%).
A floating solar cover stops the first three almost entirely. Net result: 50-70% overnight heat retention compared to uncovered.
In dollar terms, for a 20×40 inground pool heated with natural gas in a moderate climate (zone 6, May-October swim season):
| Scenario | Gas cost / season | Savings with cover |
|---|---|---|
| Uncovered, heated 82°F | $2,400 - $2,800 | — |
| Covered nightly, heated 82°F | $900 - $1,200 | $1,400 - $1,600 |
| Uncovered, no heater | $0 | — |
| Covered nightly, no heater | $0 | 4-6 extra weeks of swim season at usable temperatures |
If you don't use a heater, the savings are in swim season length rather than dollars. Most pool owners value those extra weeks at $50-$100/week of "pool enjoyment" — but that's subjective. The hard-dollar number applies to heated pools.
Water evaporation savings
An uncovered 20×40 pool in zone 6 loses about 1/4 inch of water per day in summer to evaporation. That's around 150 gallons per day, or 22,000+ gallons per season.
A solar cover reduces evaporation by 90-95%. So with a cover on overnight (when most evaporation happens), you're saving 18,000-20,000 gallons per season.
At average US municipal water rates ($4-$8 per 1,000 gallons), that's:
| Water cost (per 1,000 gal) | Annual savings |
|---|---|
| $4 (low-cost municipal) | $72 - $80 |
| $6 (US average) | $108 - $120 |
| $8 (drought-prone region) | $144 - $160 |
| $12+ (CA, AZ tiered rates) | $216 - $240+ |
If you're on a well, the cost shows up as pump electricity and well wear — harder to quantify but real.
Chemical savings
Every gallon of water that evaporates leaves the chlorine, cyanuric acid (stabilizer), and pH buffers behind. So far so good. But when you refill, you're diluting the chemistry — and that triggers extra dosing.
For a 22,000-gallon evaporation event each season:
- Additional chlorine to compensate for dilution: $40-$80/season
- Additional stabilizer (CYA): $20-$40/season
- Additional pH buffer (sodium carbonate / muriatic acid): $20-$40/season
Total chemical savings with a cover: $80 - $160/season.
Skip the DIY — get the Lux Pool motor kit
These savings only happen if the cover is actually on the pool. Motorize your reel and the cover goes on every night automatically.
View motor kits →Total annual savings for a typical pool
Adding the three categories together for a 20×40 heated inground pool in a moderate climate:
| Category | Annual savings |
|---|---|
| Heat retention (gas heater) | $1,400 - $1,600 |
| Water (municipal at $6/1,000 gal) | $108 - $120 |
| Chemicals | $80 - $160 |
| Total | $1,588 - $1,880 |
Round it: about $1,400-$1,900 per year for a typical heated residential pool.
Unheated pool? The dollar savings drop to $200-$300 (water + chemicals), but you gain 4-6 weeks of usable swim season — significant if you only have a 14-week season to start with.
Payback period: cover + reel + motor
Now let's run the payback math on the full system:
| Component | Cost |
|---|---|
| Solar blanket (Sun2Solar Crystal Clear 1600, 20×40, 12-mil) | $200 - $300 |
| Manual reel + tubes (Vingli 18-ft or similar) | $200 - $400 |
| Lux Pool motor kit (retrofits the manual reel) | $1,049 - $1,699 |
| Total system | $1,449 - $2,399 |
For a heated pool with $1,400-$1,900 in annual savings, payback is ~14-18 months. Including the motor, the full system pays itself off inside two summers.
If you already own the blanket and reel and only need the motor, payback drops to under 10 months.
The hidden variable: how often do you actually use the cover?
Here's what the payback math assumes: you put the cover on every night and take it off every morning.
In reality, most hand-crank pool owners use their cover 30-50% of the time they should. By mid-July, the daily cranking gets skipped. The blanket spends August in a wad by the equipment pad. The savings drop to maybe $500-$700/year — not the $1,400-$1,900 the math promises.
This is the single biggest argument for motorizing the reel. A 90-second button press happens every night. A 5-minute physical workout doesn't.
If you cover the pool only 50% of the nights you should, your annual savings are roughly half what the math says. Motorize the reel and you push that use rate back to 90%+, which is what makes the payback period real.
Bottom line
For a typical 20×40 heated inground pool:
- Annual savings: $1,400 - $1,900 (blanket used nightly)
- Full system cost (blanket + reel + motor): $1,450 - $2,400
- Payback: 14-18 months
- System lifespan: 4-5+ years (battery is the limiting part; replace ~$67.98)
The math works. The catch is using the cover often enough to capture the savings — which is why motorizing matters more than the blanket itself.