How to Measure for a Tarp Pool Cover: A Step-By-Step Guide

Kevin Pflug

This guide will show you how to measure for a pool cover. 90% of our customers order the wrong-sized pool cover. Be confident knowing that you’re ordering the correct cover.

Let’s dive in (pun intended).

Identify Your Pool Shape

Before we can measure the size of the pool, we need to know its’ shape.

  • Rectangle
  • Grecian
  • Round
  • Oval
  • Roman
  • Lazy L
  • 90 deg L
  • Free Form

Measure the Size of Your Pool

For inground pools:

The basic idea here is to measure the overall length and width of your pool. Easy enough if you have a rectangular pool.

For shapes that are not standard, such as grecian, free form, or Lazy L, the only way to make sure your pool is completely covered is to the overall length and width of the object.

*Note. A special case when measuring above ground pools: you have to take into account the top rails in your measurements.

Top rails come in all different widths, so be sure to include the rails in your mreasurement.*

Use the following diagrams to better understand where the measurements should be taken for the different pool shapes:

Take Water Level Into Account

We have to remember to take into account the drop in water level when measuring for your cover.

If the water level is dropped more than a foot (bottom of skimmer is about a foot), than we have to add that distance to the overall length and width.

…But how much should be added to the pool size?

A good rule is to add double to any measurement over a foot.

For example – if the water level is dropped an extra foot below the skimmer, then 2 feet should be added to both the length and width.

So, if the pool size is an 18’ x 36’ rectangle, we should really order a cover for a pool that is a 20’ x 38’ rectangle.

Another example – let’s say the water level is 2 feet lower then the bottom of the skimmer…that same 18’ x 36’ pool should now have a cover that would fit a 22’ x 40’ pool.

Don’t Forget to Include the Steps

This “step” is important, because it is often forgotten.

Let’s use our 18’ x 36’ rectangle example again.

If we have 4’ x 8’ steps protruding from the center of our shallow end, then we would really need a cover for an 18’ x 40’ pool.

If the 4’ x 8’ steps are protruding from the left or right side of the shallow end, then we would need to add the extra distance to the width of the pool…so for our example, this would end up with a cover that can fit a 22’ x 36’ pool.

Account for Non-Removable Obstacles

Perhaps you have a ladder, or a railing that is not movable (it’s cemented into the concrete, for example).

In cases like this, we can follow the same rule that we did when accounting for water level drop: double the distance.

The proper way to tackle this is as follows: First, measure the height from the deck to the top of the obstacle. Next, double that measurement

Let’s say you have a railing that rises 3 feet above the deck of the pool. We would then add 6’ to the overall length and width of the pool.

This would result in an 18’ x 36’ pool really needing a cover for a 23’ x 41’ pool.

Round Up to the Closest Pool Cover Size

Oftentimes, your measurements will result in a pool cover size that is not standard.

In instances like this, you should make sure to order the next biggest cover size that can fit your pool.

If we use the previous example above of an 18’ x 36’ pool with a railing that rises 3’ above the deck, we would need a cover to fit a 23’ x 41’ pool.

Covers are not generally sold in that size. The next biggest size, and the cover we should order, is a cover that fits a 24’ x 42’ pool.

Pool Size Versus Cover Size Confusion

One of the most confusing parts of ordering a cover is what numbers we should be looking at…pool size or cover size?

Both dimensions are usually listed.

The best way to avoid any confusion is to always think in terms of pool size only.

So, if we measured our pool to be an 18’ x 36’ rectangle, then we should order a cover that says “Pool Size: 18’ x 36’”…NOT “Cover Size: 18’ x 36’”.

Hope this clears it up!


So, that’s our step-by-step guide on how to properly measure for a tarp pool cover.

Please feel free to share this guide to anyone you know who needs help with getting a new cover.

Remember: you can always call/text us at 631-472-6275 if you would like to leave the measuring to us.

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Kevin Pflug
Kevin joined Romanelli & Son Pool Service in 2021 and hasn't looked back since! He enjoys eating his wife's delicious homemade meals and bowling with his family.

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