When it comes to protecting your swimming pool during the off-season or reducing maintenance costs during peak usage, pool covers are essential. One of the most common dilemmas pool owners face is choosing between an 8 mil and a 12 mil pool cover. Both options have benefits and trade-offs, but which one is truly better? In this article, we’ll dive deep into the details—material thickness, durability, UV protection, water retention, cost, and installation—to help you decide whether an 8 mil pool cover outperforms a 12 mil cover or vice versa.
Understanding Mil Thickness in Pool Covers
Before comparing 8 mil vs. 12 mil pool covers, it’s important to understand what “mil” means in this context:
- 1 mil = 1/1000 of an inch.
- So, an 8 mil cover is 0.008 inches thick.
- A 12 mil cover is 0.012 inches thick.
This difference may seem small, but it can significantly impact the cover’s longevity, strength, and overall performance. The primary materials used are polyethylene (PE) or polypropylene (PP), often reinforced with UV inhibitors to resist sun damage.
What Pool Covers Do
Pool covers serve multiple purposes, including:
- Reducing evaporation and water loss
- Minimizing debris accumulation
- Improving heat retention (especially with solar pool covers)
- Lowering chemical consumption
- Enhancing safety (for solid safety covers)
The thickness of the cover strongly influences how well it performs across these functions.
8 Mil vs 12 Mil: A Side-by-Side Comparison
Let’s break down the key features of 8 mil and 12 mil covers to understand which is the better option for different pool owners and situations.
| Feature | 8 Mil Pool Cover | 12 Mil Pool Cover |
|---|---|---|
| Thickness | 0.008 inches | 0.012 inches |
| Durability | Moderate | High |
| Price | Cheaper | More expensive |
| Lifespan | 1–3 years | 3–6 years |
| Weight | Lighter | Heavier |
| UV Resistance | Lower | Higher (often reinforced) |
| Application | Seasonal, short-term use | Long-term, heavy-duty |
Based on this table alone, the 12 mil cover offers better durability and UV protection, but comes at a higher cost. However, there are additional nuances that affect this decision.
Durability: Strength and Longevity
Material Strength and Tear Resistance
Thicker covers typically offer more resistance to tearing, especially in the presence of sharp objects, rough winds, or improper installation. 12 mil covers are denser and less prone to rips and punctures, particularly in areas with high debris or where lawn maintenance (e.g., hedge clippers) might pose a risk.
Lifespan Expectations
The expected lifecycle of a pool cover is directly tied to its mil rating. An 8 mil cover may last only 1 to 3 seasons, while a 12 mil cover can endure 3 to 6 seasons or more under proper care. For pool owners seeking long-term value, investing in a thicker cover can save money over time.
Weather Resistance
If you live in an area with harsh winters, high winds, or strong sun exposure, a 12 mil cover is typically the better option. Many premium 12 mil covers come with multilayer construction, including coatings that protect against UV degradation, algae growth, and chemical deterioration.
Installation Wear and Tear
Thicker covers also better withstand the stress of being spread, pulled, tightened, and anchored over multiple seasons. The extra thickness of a 12 mil cover protects against stress fractures and seam wear, especially when used with automatic reel systems or where tension is frequently applied.
UV Protection: Critical for Cover Longevity
Pool covers are constantly exposed to sunlight, making UV resistance a critical factor.
8 Mil Covers – UV Susceptibility
While many 8 mil covers are treated with UV stabilizers, their thinner structure makes them more susceptible to degradation over time. Prolonged sun exposure can weaken the plastic, causing it to become brittle and eventually break down.
12 Mil Covers – Enhanced UV Blocking
The increased thickness provides a natural barrier against UV radiation, and many 12 mil covers have additional UV inhibitor layers. This can prolong the cover’s life by up to 2–3 years, especially in sunny regions like Arizona or Florida.
Cost Analysis: Short Term vs Long Term Value
Initial Purchase Costs
On average, pool covers increase in price with thickness. Depending on the brand and coverage size, an 8 mil cover can be 20–40% cheaper than a 12 mil cover of the same size.
Total Cost of Ownership (TCO)
While 8 mil covers are cheaper upfront, they also require more frequent replacement. Let’s look at a breakdown for a 20 x 40 ft vinyl cover:
- **8 mil cover:** $200, lifespan 2 years → $100/year
- **12 mil cover:** $300, lifespan 5 years → $60/year
Over 5 years, the total cost of using 8 mil covers ($500) is significantly higher than investing in a single 12 mil cover ($300). In this case, the cost advantage flips in favor of 12 mil cover.
Repair Costs
Another hidden cost comes from repairs. 8 mil covers are more likely to tear and require patch kits—and even then, the patches often degrade. A 12 mil cover may survive light punctures with minimal repair, further enhancing its long-term value.
Installation and Usability
Manual Installation
Handling pool covers manually can be challenging, especially for larger pools. 8 mil covers are lighter, making them easier to lay down and remove—a major plus for homeowners who perform installation themselves.
Use of Pool Cover Reels
In contrast, 12 mil covers are heavier and harder to roll manually, but they perform better with automatic or assisted reel systems due to their stability and tautness. If you’re using a reel, the added weight and quality of a 12 mil cover can be an advantage.
Weathertight Sealing
Thicker materials like the 12 mil option provide a tighter, more secure seal around the edges, which helps reduce evaporation and chemical loss more effectively. If you’re looking for enhanced energy efficiency, particularly with solar pool covers, the 12 mil option tends to outperform.
Performance Metrics
Heat Retention
For solar pool covers, thickness can affect thermal efficiency. While color and material structure are more impactful, a 12 mil cover can trap and retain heat slightly better, making it more effective at maintaining pool temperature.
Water Retention and Evaporation Reduction
Both 8 and 12 mil covers do well in reducing evaporation. However, the thicker cover tends to be more resistant to water penetration, ensuring debris such as leaves and dirt don’t sink through—especially valuable in heavy rain areas.
Chemical Efficiency
Evaporation of chlorine and other chemicals can be a major cost source. Because 12 mil covers are denser, they prevent more water evaporation, which in turn reduces the frequency of chemical top-ups.
Pool Types and Use Cases
Not every pool is the same, and your usage pattern will dictate whether a thinner or heavier cover suits your needs better.
Inground vs Above Ground
- Inground pool owners often invest in long-lasting covers to protect their valuable infrastructure—making 12 mil covers ideal.
- Above ground pool owners might prefer 8 mil covers, especially for seasonal use or budget-conscious owners.
Residential vs Commercial Use
- Commercial pools (hotels, community centers, etc.) require covers that can endure continuous wear, including frequent movement, sunlight cycles, and public use. In this case, 12 mil is strongly advised.
- For casual backyard use, the 8 mil might suffice, especially if you’re replacing annually or using during milder off-seasons.
Climate Considerations
| Climate | Recommended Mil |
|---|---|
| Desert / Arid | 12 mil (high UV) |
| Cold / Snowy | 12 mil (heavy strain) |
| Temperate / Mild | 8 or 12 mil |
| Tropical / Rainy | 12 mil (water + wind stress) |
Environmental and Safety Aspects
Water Conservation
If you’re eco-conscious or live in a drought-affected area, reducing water waste is crucial. 12 mil covers reduce water loss more effectively than 8 mil ones, conserving hundreds to thousands of gallons annually.
Safety Covers
Note that safety covers, designed to bear the weight of people or animals, are often made of 20 mil material or more, and are designed for permanently fixed systems. Neither 8 mil nor 12 mil is suitable for safety applications—they are considered winter or thermal covers, not load-bearing.
Which One Should You Choose?
The answer ultimately depends on your specific scenario.
Choose 8 Mil If:
- You’re on a budget
- You have a mild climate
- You’re a seasonal pool owner (only covering a few months a year)
- You manually install and remove your cover
- You already have a permanent safety cover and just want heat retention
Choose 12 Mil If:
- You live in a high sun or high wind area
- You use the pool year-round or for long seasons
- You want the cover to last for multiple years
- You’re looking for low-maintenance, heat-efficient solutions
- You have a community or commercial pool
Conclusion: Balancing Performance and Affordability
In the debate of Is 8 mil pool cover better than 12 mil, the answer hinges on the user’s specific needs, climate, and budget. An 8 mil cover is a cost-effective option for casual use and shorter periods, while a 12 mil cover offers superior durability, UV protection, and long-term value. For serious pool owners focusing on efficiency, heat retention, and reduced replacement frequency, 12 mil is typically the better pick.
If you want to maximize pool maintenance savings over time, invest in the highest quality cover your budget can allow—especially if you live in sunny or harsh climates. However, for short-lived applications and budget constraints, an 8 mil cover may be more appropriate.
Ultimately, by aligning your choice with your unique environment, usage, and goals, you can reduce chemical costs, save water, and prolong your pool’s life—a win regardless of your pick.
Is a thicker pool cover always better?
While a thicker pool cover, such as a 12 mil option, generally offers more durability and heat retention, it’s not always the best choice for every situation. Thinner covers like the 8 mil can be more flexible, easier to handle, and often more affordable. They may also be sufficient for seasonal use or in climates with milder temperature variations.
Ultimately, the decision depends on your specific needs, including how long you plan to use the cover, your local climate, and your budget. If you’re looking for long-term investment and maximum energy efficiency, especially in cooler regions, a 12 mil cover may make more sense. However, for casual use or temporary setups, the lighter 8 mil version could serve just as well without the higher cost.
What does “mil” mean when referring to pool covers?
Mil is a unit of measurement used to indicate the thickness of a pool cover. One mil equals one-thousandth of an inch (0.001 inches), so an 8 mil cover is 0.008 inches thick and a 12 mil cover is 0.012 inches thick. This measurement helps users compare the sturdiness and effectiveness of different covers, especially when it comes to heat retention and durability.
Understanding the mil thickness allows pool owners to make informed choices based on their local climate and usage needs. Covers with higher mil ratings typically offer better insulation, meaning they can keep pool water warmer and reduce evaporation and chemical loss. The choice between 8 and 12 mil covers often boils down to how much protection and energy efficiency is needed.
How does the 8 mil vs. 12 mil pool cover affect pool heating costs?
There is a noticeable difference between 8 and 12 mil covers when it comes to heat retention. The 12 mil cover, being thicker and more insulating, reduces heat loss more effectively, especially at night or during colder weather. By maintaining higher water temperatures, it can significantly cut down on the running costs of pool heaters, making it an energy-efficient choice in the long run.
Conversely, while the 8 mil cover still provides some level of insulation, it’s less effective in retaining heat, which may require more frequent use of heating systems. This could lead to higher energy bills for pool owners in chillier climates. However, for those in warmer areas or using the pool only occasionally, an 8 mil cover may be sufficient to maintain comfortable temperatures without added costs.
Which is better: solid or mesh safety covers with 8 or 12 mil thickness?
Solid and mesh covers serve different purposes and their effectiveness isn’t directly tied to thickness alone. A solid 12 mil cover offers better insulation and evaporation control, making it ideal for winterizing or when maximum heat retention is needed. On the other hand, mesh 8 mil safety covers are designed to allow water and sunlight to pass through, making them a popular choice for safety and long-term pool protection during off-seasons.
The best option depends on your goals. If you want to maintain warmth and minimize chemical loss, a solid 12 mil cover is preferable. But if safety is a concern—especially in areas with heavy debris or where children and pets are around—a mesh 8 mil cover could be more appropriate. In these cases, durability and functionality matter more than just the mil rating.
Can an 8 mil cover withstand extreme weather?
An 8 mil pool cover provides decent protection against mild weather conditions, moderate sun exposure, and light debris. However, it may not be the best option for regions that experience extreme weather, such as heavy storms, snow, or intense UV exposure. Thinner materials tend to wear out more quickly under such conditions, which can lead to tearing or reduced efficiency over time.
If your pool is exposed to harsh elements, investing in a 12 mil cover would provide better resistance to wind, rain, and sun damage. These covers are more robust and can handle the stress of fluctuating temperatures and outdoor challenges better than their thinner counterparts. For extreme climates, enhanced durability is worth the added expense.
Do 12 mil covers reduce evaporation more effectively than 8 mil covers?
Yes, 12 mil pool covers are significantly more effective at reducing evaporation compared to 8 mil options. Their greater thickness means they create a tighter seal on the water surface, minimizing water loss due to heat and wind. This can be especially beneficial in arid climates where water conservation is a concern and frequent refilling can be costly.
In addition to reducing evaporation, thicker covers also help maintain chemical balance by limiting exposure to sunlight and contaminants. The 8 mil cover does provide some evaporation control, but not as efficiently. For pool owners looking to optimize water and chemical usage while reducing maintenance, a 12 mil cover can make a meaningful difference over time.
How do 8 mil and 12 mil covers impact chemical maintenance in a pool?
The choice between an 8 mil and a 12 mil pool cover can influence how often you need to add chemicals to your pool. A 12 mil cover, due to its thickness and better insulation, provides a more effective barrier against debris, UV rays, and evaporation, all of which can destabilize chemical levels. This leads to more consistent water chemistry and less frequent adjustments.
In contrast, an 8 mil cover offers a somewhat lighter-duty solution. While it can still reduce chemical loss, it doesn’t offer the same level of protection as a 12 mil cover, particularly in high-sunlight conditions or when the pool is exposed to wind and dust. As a result, pool owners using thinner covers may need to test and adjust their water chemistry more frequently to maintain safe and clean swimming conditions.