Measuring your above ground pool for a cover is the single most important step in ensuring a proper, secure fit. An accurate measurement prevents the frustration of a cover that is too tight, rendering it impossible to install, or too loose, which allows it to sag, collect water, and become a safety hazard. By taking the time to follow a precise methodology, you protect your investment, extend the life of your pool, and make the seasonal opening and closing process significantly smoother.
While the concept seems simple, there is a distinct difference between measuring for a standard cover and measuring for a safety cover. Standard covers are typically flexible and designed to stretch over the pool, allowing for some variance. Safety covers, however, are rigid and must be custom-fitted to the exact dimensions of the pool shell, as they are designed to bear the weight of snow and rain without collapsing. Understanding this distinction is crucial before you grab your tape measure.
Understanding Pool Dimensions
Above ground pools are not perfect circles or rectangles; they are specific shapes defined by their wall structure. The nominal size printed on the box, such as 15 or 24 feet, often refers to the diameter of the pool frame rather than the actual water surface. For a cover to fit the pool shell, you must measure the structure itself, not the packaging label. This involves measuring the total width of the pool basin from one inner wall to the opposite inner wall, passing through the center.
Round Pools
Measuring a round pool is straightforward but requires precision. You must determine the diameter of the pool shell, which is the complete distance straight across the circle, passing through the center point. The most accurate method is to measure from the inside edge of the wall on one side to the inside edge of the wall directly opposite. If accessing the exact center is difficult, you can measure the total outer width of the pool frame and subtract the thickness of the top rail on one side to estimate the inner diameter.
Oval and Rectangular Pools
Oval and rectangular pools introduce a layer of complexity because they involve measuring both the length and the width. For these models, you need to identify the longest points for both dimensions. Measure the total distance from the innermost point of the long side to the opposite innermost point for the length. Repeat this process for the width, measuring the shortest straight line between the short sides. It is vital to measure the rectangular section of the pool bed itself, avoiding the curved corners, as the cover material is designed to fit the straight lines of the pool frame.
The Step-by-Step Measurement Process
To ensure accuracy, it is best to take multiple measurements in several locations. Pool walls can warp slightly, and the frame may not be perfectly level. By taking three measurements—crosswise, lengthwise, and diagonally—you can calculate an average that accounts for any irregularities. This average measurement is the dimension you will use when ordering your cover, ensuring the cover is tailored to the actual shape of the pool rather than a perfect geometric ideal.
| Pool Shape | Measurement Type | How to Measure |
|---|---|---|
| Round | Diameter | Measure straight across the center, inside the wall lip, from edge to edge. |
| Oval | Length & Width | Measure the longest straight line (length) and the shorter straight line at 90 degrees (width), staying within the rectangular section. |
| Rectangular | Length & Width | Measure the distance between the two longest parallel walls and the two shortest parallel walls, avoiding the diagonals. |
Accounting for Overlap and Tension
Once you have the primary dimension, you must consider the mechanism that secures the cover. For sand or water-filled above ground pool covers, you need to know the size of the frame itself to ensure the cover overlaps the wall sufficiently. Typically, you measure the top rail diameter or the overall frame width. For covers that use winches or straps, the cover size is usually based on the pool shell dimensions, but you must confirm whether the manufacturer requires you to subtract the wall thickness. Always refer to the specific instructions provided by the cover manufacturer, as they dictate the exact fit parameters.
Safety Considerations for Above Ground Installations
Safety covers are engineered to support significant weight, and an improper fit can compromise this integrity. If the cover is too small, it will not anchor securely to the deck, creating a dangerous scenario where the cover could pull away partially or completely. If it is too large, the tensioning straps will overstretch, leading to premature tearing. When measuring for a safety cover, precision is non-negotiable. It is highly recommended to have two people conduct the measurements: one to hold the tape measure steady at one end and the other to read the measurement at the opposite end, ensuring the tape remains perfectly taut and level across the entire surface.
Final Verification and Ordering
Before finalizing your purchase, double-check that your measurements correspond to the unit of measurement (feet or inches) required by the retailer. Many mistakes occur when customers assume the pool size is in feet while the website expects inches. Round your measurements up to the nearest sixteenth of a foot if you are ordering custom, and always check the return policy. A cover that is even half an inch off can be difficult to install and may void the warranty. Taking meticulous notes and clear photographs of the pool from an overhead angle can also provide valuable context for the retailer or manufacturer, ensuring the cover is produced to meet your exact specifications.
