How to Measure Your Pool for a Cover, Any Shape

On this page (8 sections)

1. What should you measure before choosing a pool cover?
2. How do you measure an irregular pool?
3. How do steps, ledges, and decks affect the measurements?
4. How much overlap should a winter pool cover have?
5. How do inground cover measurements differ?
6. How do you measure for a solar pool cover?
7. What mistakes can lead to a poor fit?
8. How do you choose the right pool cover size?

Measure the pool at its widest points, then match those dimensions to the cover type and its fit instructions. Record the water opening, steps, ledges, and deck features that affect the cover’s shape or attachment.

A pool’s nameplate size may not include every feature that matters for fit. Before you choose a cover, decide whether it must float over the water, reach beyond the pool edge, or attach to anchors in the deck.

For a quick overview of the main options, see our guide to types of pool covers. The right measurements depend on whether you’re sizing a winter, safety, or solar cover.

What should you measure before choosing a pool cover?

Measure the pool opening and the full area the cover needs to reach. Include any steps, attached spas, ledges, or other sections that the cover must span.

Gather a tape measure, paper, pencil, and a helper for long spans. Measure in feet and inches, and write down each result as you go.

Start with these notes:

• Pool shape and whether its sides are straight or curved
• Longest length and widest width
• Diameter for a round pool
• Dimensions and position of steps, ledges, or bump-outs
• Distance from the pool edge to nearby walls, fences, and deck edges
• Any rails or features the cover must pass over or attach around

Measure the pool itself instead of relying only on an old cover. A used cover may have stretched, and its size may include overlap that does not describe the pool opening.

How to measure a rectangular pool for a cover

Measure the inside length and width of the pool opening, from edge to edge. Take each measurement at the widest points, even if the pool walls appear straight.

Measure the length in at least two places and the width at both ends and the middle. If the numbers differ, note the largest measurement and where you took it.

If the cover must extend onto a deck or past the pool edge, record that area separately. Do not add extra inches to your pool dimensions until you’ve checked how that cover is sized.

How to measure a round pool for a cover

Measure the diameter across the center of the pool, from one inside edge to the opposite inside edge. Repeat the measurement along a second line at a right angle.

If the two diameters differ, write down both and use the larger one when comparing size options. Also note whether the cover will need to pass over top rails or secure around the pool’s outer edge.

How to measure an oval pool for a cover

Measure the long axis and short axis across the pool opening. Take each measurement between opposite inside edges, at the widest points.

An oval pool can have different end curves, so record a quick sketch and mark where each measurement was taken. This can help you distinguish a standard oval from a shape with flatter ends or an attached step section.

How do you measure an irregular pool?

Measure the longest length and widest width, then map each part of the outline that changes the cover’s shape. A single length and width may help compare sizes, but they may not describe a fitted cover accurately.

Sketch the pool from above. Label the overall dimensions, then add each step, ledge, corner, and bump-out with its own length, width, and distance from a fixed edge.

For a fitted safety cover, record the deck and anchor layout as well as the pool outline. The shape and placement of anchors can affect fit, so follow the cover maker’s template and measurement process before ordering.

For a solar blanket that can be trimmed, measure the water surface and trace its shape carefully. Our guide explains how to cut a solar pool cover to fit.

How do steps, ledges, and decks affect the measurements?

Measure every feature the cover needs to span or attach to. A cover that fits the main pool opening may still miss an attached step or conflict with the deck.

For steps or a shallow ledge, measure the length and width of the section and how far it extends from the main pool shape. Mark its position on your sketch so you know where the extra coverage belongs.

For a safety cover, note the available deck surface and anchor positions. If you are deciding between cover styles, our guide to safety covers versus winter covers explains why their fit requirements differ.

For a winter cover, identify what will secure its edges and whether the cover is meant to overlap the pool. Above-ground covers may be sized by pool dimensions while the cover itself is larger to allow for overlap.

How much overlap should a winter pool cover have?

Use the cover’s stated pool size and overlap instructions, rather than adding a standard allowance yourself. Overlap varies by cover and pool setup.

For example, the Robelle 18 x 33 ft Oval Winter Pool Cover is designed for an 18 x 33 ft above-ground pool and includes a 4 ft overlap. Its overall cover size is 22 x 37 ft, so the pool size and material size describe different measurements.

A round cover may also be identified by the pool size it fits. The Navy Blue 28 ft Round Winter Pool Cover is made for a 28 ft round above-ground pool.

Before ordering, check how the cover is intended to sit and secure. The product’s stated pool size does not by itself tell you whether it will clear your particular rails, deck, or attachments.

How do inground cover measurements differ?

An inground winter cover may be sized by the pool opening, but you should still check the cover’s overlap and securing method. Measure the full pool length and width, then record nearby deck edges and anything the cover needs to clear.

The Navy Blue 25 x 45 ft Inground Winter Cover is listed for a 25 x 45 ft rectangular inground pool and has a stated 4 ft overlap. Confirm the exact fit instructions for your pool and installation.

Safety covers require extra care because the cover must align with the pool shape and anchor points. Use the maker’s measuring template and check clearances before placing anchors or ordering a custom fit.

How do you measure for a solar pool cover?

Measure the water surface, including its longest length and widest width. If the cover is designed to be trimmed, start with a size that covers the full outline and trim only after checking its instructions.

The VEVOR 18 ft Round 16 Mil Solar Cover is an 18 ft round option that can be trimmed for irregular pool shapes. Confirm the pool dimensions and cover instructions before cutting.

A solar cover rests on the water, so its measurement job differs from a winter cover that may extend over the pool edge. For more on the fit process, see how to cut a solar pool cover to fit.

What mistakes can lead to a poor fit?

The most common sizing mistake is treating a pool’s advertised size as the complete cover measurement. Different covers may refer to pool size, material size, or the area needed for anchors.

Avoid these errors:

• Measuring only one side of a pool that may not be square or round
• Measuring an old cover instead of the pool
• Forgetting steps, ledges, rails, or an attached spa
• Adding overlap without checking the cover’s instructions
• Assuming a solar cover and winter cover fit the same way
• Ordering a safety cover without mapping the anchor layout

Take each measurement twice and label it on your sketch. If an important dimension is uncertain, remeasure before ordering rather than guessing.

How do you choose the right pool cover size?

Choose the cover only after you know the pool shape, its dimensions, and how that cover installs. Compare your measurements with the cover’s intended pool size, overlap, trim guidance, or anchor template.

If you’re comparing cover materials and uses, start with our guide to pool cover types and their differences. For help narrowing fit by pool style, see pool covers and fit for inground pools.

Pick a winter cover by the pool size and required edge coverage. Choose a solar cover by the water surface it must cover, and use the trim instructions if the outline is irregular.

For a safety cover, follow its template and anchor layout closely.

FAQ-\

Frequently asked questions

Should I measure the pool or the old cover?

Measure the pool itself first. An old cover may have stretched, shrunk, or included extra material for overlap, so its dimensions may not match the pool opening.

Use the pool measurements to compare against the new cover’s fit instructions, including any overlap or anchor requirements.

How much extra material should a winter pool cover have?

The needed extra material depends on the cover and pool style. Some above-ground covers include overlap beyond the stated pool size, while other covers have different installation requirements.

Check the cover’s instructions for the intended pool size and overlap before ordering.

How do I measure an irregular pool for a cover?

Measure the longest length and widest width, then record the shape and dimensions of every step, ledge, or bump-out the cover needs to cover. For a fitted safety cover, also map anchor locations and follow the cover maker’s template process so the cover matches the deck layout.

Can I trim a solar cover to fit my pool?

Many solar covers can be trimmed to match a pool outline, but confirm that the cover is intended to be cut and follow its instructions. Measure the pool carefully first, then trim gradually so you do not remove too much material.

See our guide to cutting a solar cover to fit.

Do I use the same measurements for a safety cover and a winter cover?

No. Both start with pool dimensions, but a safety cover may need a precise shape and anchor layout, while a winter cover may need extra material for overlap or securing.

Identify the cover type before measuring, then follow its specific sizing and installation instructions.