Ordering a safety cover is one of the few pool purchases where a one-inch mistake costs you the entire cover. The good news: measuring an inground pool for a Loop-Loc safety cover is straightforward once you understand one rule that trips up almost every first-time buyer.
That rule is this: you measure the pool, not the cover.
Measure the Water, Not the Deck
Every Loop-Loc cover is manufactured with an overlap allowance built in. The cover is intentionally larger than the pool so it can extend past the edge and anchor into your deck. That overlap is added at the factory — you never add it yourself.
So when you see an 18' x 34' cover listed, that means it fits an 18-foot by 34-foot pool. The finished cover panel is larger than that. If you measure your existing worn-out cover and order that size, you will end up with a cover that is far too big.
Measure from tile line to tile line, or from the inside edge of the coping to the inside edge of the coping on the opposite side. That is your pool dimension.
Step 1: Determine Your Pool Shape
Before you pull out the tape, identify which family your pool falls into. This determines whether you can buy a stock cover off the shelf or need a custom one.
- True rectangle — four 90-degree corners, no steps intruding into the swimming area. Shop Mesh Rectangle covers or Solid Rectangle covers.
- Rectangle with a step section — the most common inground configuration on Long Island. The step protrudes beyond the rectangle and needs its own cover panel.
- Grecian, Roman, or Jewel — cut corners or curved ends. See Mesh Grecian with Center Step or Mesh Jewel.
- Round, oval, or square — browse Mesh Round, Mesh Oval, and Mesh Square.
- Freeform, lagoon, or anything with a curve you can't name — this is custom territory. Head to Custom Safety Covers.
Step 2: Measure the Main Body of the Pool
Grab a 100-foot tape measure and a helper. A short tape that you "walk" down the pool in sections introduces error every time you reposition it.
- Measure the width at three points — near each end and at the middle. Record all three.
- Measure the length at three points — along each side and down the center.
- Measure both diagonals, corner to corner.
If your three width readings and three length readings all match, and both diagonals match each other, you have a true rectangle and can order a stock size. Popular stock sizes include 16' x 24', 16' x 30', 18' x 34', 20' x 36', and 22' x 44'.
If the diagonals differ by more than an inch or two, your pool is out of square — which is extremely common in pools built before the 1990s. Order a custom cover instead of forcing a stock size.
Step 3: Measure the Step or Sun Shelf
This is where most orders go wrong. A step section is described by two things: where it sits and how far it protrudes.
Where it sits
Stand at the end of the pool where the step is and face the water. Then classify it:
- Center step — equal distance from both corners. Shop Mesh Rectangle with Center Step or Solid Rectangle with Center Step.
- Left offset step — pushed toward the left corner as you look at it. Shop Mesh Rectangle Left Offset Step.
- Right offset step — pushed toward the right corner. Shop Mesh Rectangle Right Offset Step.
- Flush step — one side of the step is level with the pool wall rather than centered or offset. See Left Flush Step and Right Flush Step.
Left versus right is decided from the perspective of someone standing outside the pool looking in at the step. Write that down before you forget which way you were facing — it is the single most common reordering mistake we see.
How far it protrudes
Measure the step's width (parallel to the pool wall) and its projection (how far it sticks out from the wall). A 4' x 6' step means it is 6 feet wide and projects 4 feet — or the reverse, depending on the manufacturer's convention, which is exactly why you should write down both numbers with labels rather than relying on the shorthand. Our 12' x 24' with 4' x 6' center end step listing shows how these are described.
Step 4: Check Your Deck
A safety cover is only as strong as what it anchors into. Walk the full perimeter and note:
- Deck material — concrete, pavers, wood, or a mix. This determines your anchor type.
- Available deck width — you need continuous solid deck around the pool to set anchors. If a section of your pool borders a raised wall, planter bed, grass, or a rock waterfall, flag it.
- Obstructions — diving boards, slides, handrails, ladders, and light niches all need to be accounted for.
- Raised walls or spa spillovers — an attached raised spa almost always pushes a pool into custom.
If your deck is pavers or you have limited solid substrate, you may need extra long brass anchors. For areas where you cannot drill directly into the deck, 15" aluminum pipe with brass anchor is the standard workaround.
When You Need a Custom Cover Instead
Order a custom Loop-Loc cover if any of the following are true:
- Your diagonals are off by more than a couple inches
- The pool is freeform, kidney, lagoon, or L-shaped
- There is an attached spa, sun shelf, or tanning ledge
- A raised bond beam, waterfall, or rock feature interrupts the perimeter
- A diving board or slide sits inside the cover footprint
- Your pool has radius corners — though some are covered by Mesh Rectangle with Center Step and Radius Corners
For custom orders, Loop-Loc uses an A-B measurement method: two reference points are established on the deck, and the distance from each reference point to every point along the pool perimeter is recorded. It produces a precise digital map of an irregular shape. It also is not a DIY job for most homeowners — a measuring error here is expensive and non-returnable.
Before You Click Order
Run through this list one final time:
- Pool dimensions recorded, not cover dimensions
- Diagonals checked and matching
- Step position confirmed (center, left offset, right offset, or flush) from outside the pool looking in
- Step width and projection both written down
- Deck material identified for anchor selection
- Obstructions noted
- Color and anchor type chosen at checkout
Ready to shop? Start with the full Loop-Loc Safety Cover collection. Not sure whether mesh or solid is right for your pool? Read our breakdown of Loop-Loc mesh vs. solid safety covers next.
Still not confident in your numbers? Email support@suntekonline.com with your measurements and a photo of the pool. We would rather spend ten minutes checking than have you sit on a cover that does not fit.