Selecting the correct cover for your above ground pool is the single most important step in protecting your investment, yet it is often the most rushed. A proper cover keeps debris out, reduces water evaporation, and significantly extends the life of your pool liner by shielding it from damaging UV rays. To achieve this, you must first learn how to measure above ground pool size accurately, moving beyond simple diameter checks to understand the nuances of your specific structure.
Why Standard Measurements Are Not Enough
Many homeowners make the mistake of assuming their pool is a perfect circle and measuring only the frame width. While the nominal diameter is a starting point, the wall height, top rail configuration, and slight variations in the metal frame can render a standard round cover ineffective or difficult to secure. The goal of measuring above ground pool size is to find a cover that sits snugly within the top shelf, creating a taut surface that prevents wind from lifting it and rain from pooling on it.
Identifying Your Pool Wall Style
Before grabbing a tape measure, you need to categorize your pool design, as this dictates which dimensions you take. There are three primary styles: Steel Wall pools, where the wall panels are vertical and overlap; Top-Rail pools, where the top rail itself is a single, large component that the cover wraps around; and Hybrid or Screw-Wall pools, which use angled brackets. Each style requires a slightly different approach to ensure the cover fits securely over the wall lip.
Step-by-Step Measurement Process
With your pool identified, you are ready to gather your tools. You will need a fiberglass tape measure (metal can be cumbersome), a notepad, and potentially a helper to hold the tape steady. Unlike indoor projects, you are measuring in an open environment, so choose a time when the wind is calm to prevent your measurements from flapping away or becoming inaccurate.
Measuring the Pool Diameter
To measure above ground pool size for the diameter, hook the tape measure inside the lip of the pool at the edge, pull it across to the opposite inner edge, and lock the tape. It is best to take this measurement in two perpendicular directions—forming a cross—to check for any oval distortion. Record the largest measurement; this ensures the cover will accommodate the widest point of the pool, preventing tight spots that could tear.
Measuring the Wall Height
The wall height, or wall rise, is the vertical distance from the top of the top rail or shelf to the ground. This is crucial because covers are sold to fit specific wall heights. If the wall is too high, the cover will sag and collect water; if it is too short, the cover will not reach the ground to anchor properly. Measure from the top of the uppermost structural rail down to the ground surface where the wall meets the patio.
| Pool Type | Key Feature | Best Cover Style |
|---|---|---|
| Steel Wall | Interlocking panels with a flat top shelf | Overlaps or strap-on covers |
| Top-Rail | Single, curved top rail the cover wraps over | Top-mount or snap-over covers |
| Hybrid/Screw-Wall | Angled brackets supporting the top rail | Custom template covers |
Accounting for the Top Rail
For Top-Rail pools, measuring above ground pool size involves factoring in the bulk of the top rail itself. You cannot simply measure the inner diameter of the frame; you must measure the outer diameter of the top rail. This is because the cover must stretch over this rail and then hang down the sides. Failure to include the rail width in your calculation will result in a cover that is too small to install properly.
Once you have gathered the diameter and wall height, you are ready to translate these numbers into a product specification. Most reputable cover manufacturers recommend adding six inches to both your length and width measurements to allow for secure overlap and tamping down into the coping track. This slight overage ensures the cover remains taut and stable even during high-wind events, providing a safer barrier around the pool.
