How to Measure Your Pool for a Pool Cover

A custom-cut cover is made to the exact numbers you give us. Get them right and the cover sits across the whole surface, rolls cleanly and lasts its full life. Get them wrong and no amount of manufacturing quality rescues the fit.

The good news: whatever shape your pool is, it comes down to two numbers — a length and a width. This guide shows you how to get those two numbers for every pool type, what else to record alongside them, and how to check your work before you order.

The two rules that apply to every pool

1. Measure at the waterline. Every dimension is taken at the normal operating water level, from the inside faces of the pool walls — not across the coping, not across the paving. A floating cover sits on the water, so the water surface is what it's cut to fit. Measuring the paving instead of the water is the most common and most expensive mistake, and it typically adds 200–400mm to both figures before you've started.

2. Measure the smallest rectangle that contains your pool. Covers are manufactured from rolled material welded in straight runs, so every pool — curved, kidney, freeform, Roman end — is measured as a rectangle. You are not tracing your pool's outline. You are finding the smallest rectangle the whole water surface fits inside.

Those two rules do about 80% of the work. The rest is knowing what else your particular shape needs recorded.

Before you start

• A long tape measure — fibreglass or steel, 20–30 metres. A cloth tape stretches. A short tape forces you to measure in stages, which compounds error.

• A second person for any pool over 10 metres. One person holding a tape that far will let it sag, and sag reads long.

• A rope, hose or string if your pool is curved or irregular.

• Your phone, for photos.

Top the pool up to its normal level first if it's low. Work in metres, record to the nearest centimetre, measure everything twice.

Quick reference: what to record for your shape

Your pool	Measure	Also record
Rectangular / square	Length × width at waterline	Diagonals, corner style
Rectangle, rounded or cut corners	Length × width to the outermost points	Corner radius or cut size
Roman or Grecian end	Length to the furthest point of the curve × width	Which end the curve is on
Lap pool	Length × width	Whether a tape reaches — split and add if not
L-shaped / swim-out	Two rectangles	How they sit relative to each other
Kidney	Rope rectangle: length × width	Photos of the curve
Oval	Length × width at widest points	—
Freeform	Rope rectangle: length × width	Photos from all four sides
Circular	Diameter at waterline, twice	—
Figure-8	Rope rectangle around both lobes	Waist width and position
Plunge pool	Length × width	Nothing unusual
Above-ground round	Diameter at waterline, inside the wall	Wall height, top rail width
Above-ground oval	Length × width, inside the wall	Wall height, top rail width
Any pool with steps	Main rectangle + step separately	Step size, position, which side
Any pool with an attached spa	Pool rectangle + spa rectangle	How they connect

Detail on the ones that trip people up follows.

Rectangular and square pools

[DIAGRAM: overhead rectangle, arrows for length and width at waterline, dashed diagonals]

1. Length — the longest side, at the waterline, in a straight line.

2. Width — the shortest side, at its widest point, perpendicular to the length.

3. Measure both again from the opposite direction to confirm.

4. Check the diagonals. Corner to corner, both ways. Equal diagonals mean a true rectangle. Unequal means your pool is out of square — record the longest length and widest width and tell us the difference, because we cut to the larger figure.

Keep even tension on the tape. Over 10 metres a sagging tape reads long by several centimetres.

Rounded or cut corners: ignore the curve entirely. Measure to the widest and longest points as if the corners were square, then note the corner detail so it can be finished to match.

Roman and Grecian ends

[DIAGRAM: rectangle with one semicircular end, bounding rectangle overlaid dashed]

A Roman end is a semicircular end on an otherwise rectangular pool; a Grecian end is a stepped or angled variation on the same idea.

Measure the length from the flat end to the furthest point of the curve, and the width across the straight section. Tell us which end the curve is on. The cover is made to the full bounding rectangle and finished around the curve.

Don't measure to where the curve starts. That's a shortfall of several hundred millimetres and it shows.

Lap pools

Long and narrow, and the length is often beyond a single tape run. If you have to split it, mark your halfway point with something that doesn't move, measure each half twice, and add them. Don't pace it, don't estimate the remainder.

Width matters more on a lap pool than on any other shape, because the cover rolls along its width — a few centimetres out over a long roll shows badly. Take the width at three points along the length and record the widest.

L-shaped pools and swim-outs

[DIAGRAM: L-shape divided into two labelled rectangles, A and B]

Don't force an L-shape into one rectangle. You'll either leave water uncovered or pay for material you can't use.

1. Measure the main pool body as rectangle A.

2. Measure the extension or swim-out as rectangle B.

3. Record where B sits relative to A — which end, which side, and whether the two overlap.

We combine them into one welded cover.

Kidney, freeform and figure-8 pools

[DIAGRAM: kidney outline with rope forming the bounding rectangle around it]

These use the rope method:

1. Lay a rope, hose or string on the paving around the outermost points of the pool.

2. Work it into the smallest rectangle that still contains the entire water surface, with corners as close to square as you can get.

3. Measure the length and width of that rectangle.

4. Photograph it from both ends and both sides before you pick the rope up.

For a figure-8, the rope goes around both lobes as a single rectangle. Also record the width at the waist and how far the waist sits from one end, because that's where the material behaves differently as it rolls.

Oval pools

Measure the length at the longest point and the width at the widest point, both at the waterline. No rope needed — an oval's outermost points are easy to find by eye. Take the width twice at slightly different positions to make sure you've found the true widest point.

Circular pools

One number: the diameter at the waterline, across the widest point straight through the centre. Take it twice at different angles. If the readings differ, the pool isn't perfectly round — use the larger.

Above-ground pools

Measure inside the wall at the waterline, not across the top rail. The top rail can sit 100–200mm proud of the water surface all the way round, and measuring across it makes the cover oversized.

Also record the wall height and the top rail width. These determine how the cover sits on the water. Above-ground pools sit higher and shorter than in-ground pools, so tell us the wall height before you add a reel.

Steps, benches and tanning ledges

[DIAGRAM: rectangle pool with corner step shaded, dimension arrows and "standing at shallow end" figure]

If your pool has a step area, bench or tanning ledge, measure it separately:

• Its length and width

• How far it sits from one end of the pool

• Which side it's on

For the side: stand at the shallow end looking down the pool and call it left or right from where you're standing. Record it in exactly that form — "left side, standing at the shallow end" — and there's no ambiguity later.

Corner steps, full-width steps and mid-length benches are all handled the same way. Because covers are welded, a step area is built into a single cover when it's measured and described correctly.

Attached spas

Measure the spa as its own rectangle, independent of the pool. Record how it connects — spillway, shared wall, raised or level with the pool — and whether you want it covered as part of the pool cover or as a separate cover. Photograph the join.

A raised spa needs its own cover. A level, flush spa can usually be welded into the main cover — send the photos and we'll confirm which applies before anything is cut.

Negative edge, wet edge and rock edge pools

Measure to the water surface, which on these pools is not the same as the structural edge.

On a negative or infinity edge, the water runs over one wall — measure to that wall's inside face. On a rock or natural edge, ignore the rock overhang entirely and measure the actual water surface underneath it. Record any rock shelf that sits over the water, because it affects how the cover sits and where it can be rolled from.

Which end your reel sits on

If you're adding a reel, tell us which end and which side.

The cover rolls along its width onto the reel tube, so the reel end determines which way the material runs — and where a step area falls in that roll. A step that folds neatly rolling from one end can bunch awkwardly rolling from the other.

It also affects reel selection. A manual or motorised reel sits on the poolside surface and needs clear deck space at the chosen end. A bench-housed reel has its position fixed by the bench, so that has to be confirmed before the cover is cut.

How your numbers become a cover

Your length and width define a rectangle. That rectangle's area in square metres is what your cover is made from and priced on.

A 10m × 5m pool is 50 square metres. So is a kidney pool whose rope rectangle measures 10m × 5m — even though less of that material ends up over water, the cover is still cut from a 50 square metre piece. That's why the rope rectangle has to be the smallest one that contains the pool: every centimetre of slack is material you pay for and don't use.

Depth is irrelevant to a cover. Only the surface matters.

Trim allowance: upturn versus waterline cut

Every cover is made 150mm larger than your measurements on each dimension, then finished one of two ways.

Upturn cut leaves a small margin that turns up toward the coping. Useful in leafy or exposed positions — the raised edge helps hold debris on the cover rather than letting it wash in — and it allows for the natural movement of the material over time.

Waterline cut follows the water's edge exactly. It sits flatter and looks tidier, with less allowance for movement.

Which suits you depends on the pool and how you use the cover. Don't add anything to your measurements for either — the 150mm is applied during manufacture. The cover trims with sharp scissors once it's on the water and has settled.

Debris covers are measured differently

A debris cover doesn't float. It anchors over the pool edge and is tensioned, so it needs material beyond the water surface to fix to.

Measure a debris cover with a 200mm overlap on every side. Don't measure it to the waterline. This is the one exception to everything above, and getting it wrong means a cover that can't be secured.

Check before you order

Professionals verify every dimension three times:

1. Measure it.

2. Measure it again from the opposite direction.

3. Cross-check it — a second person, a different tape, or a laser.

Two readings within 5cm of each other are fine; take the larger. A difference of more than 10cm means something is wrong with the technique, not the pool. Re-measure before you order rather than after.

On phone apps: A measuring apps are typically accurate to within only 5–10cm, which is enough to show on a finished cover. Use them for a rough idea, confirm with a tape.

The mistakes that actually cost money

Mistake	What happens	How to avoid it
Measuring the paving instead of the water	Cover oversized, sits badly	Measure at the waterline, inside the walls
Measuring across an above-ground top rail	Cover too big by 200–400mm	Measure inside the wall at the waterline
Measuring a Roman end to where the curve starts	Cover short by several hundred mm	Measure to the furthest point of the curve
Treating an L-shape as one rectangle	Water uncovered, or wasted material	Two-rectangle method
A loose rope rectangle on a freeform pool	Paying for material you don't use	Tighten the rope to the smallest containing rectangle
Forgetting the step, or getting the side wrong	Cover doesn't fit around the step	Measure separately, state the side from the shallow end
Letting the tape sag	Reads long by several centimetres	Fibreglass or steel tape, even tension, second person over 10m
Measuring a debris cover to the waterline	Nothing to anchor with	200mm overlap on every side
One measurement, no check	Errors surface on delivery	Measure everything twice

Your measurement record

Have these ready before you order:

Pool shape
Length at waterline (m)
Width at waterline (m)
Second rectangle, if L-shaped (m × m)
Step / bench size and position
Which side, standing at the shallow end
Attached spa dimensions
Reel end and side
Photos taken	Both ends, both sides, rope rectangle

Rectangular, oval and round pools price live in the configurator as you enter them — no quote request, no waiting. Kidney, freeform and L-shaped pools can't be priced from two numbers, so send us the address and we'll measure the pool ourselves and come back with a price.

Price my cover →

Frequently asked questions

Do I measure to the tiles or to the water? To the waterline, from the inside faces of the walls. The cover floats on the water's surface, so that's the surface it's cut to fit.

My pool is an odd shape — how do I measure it? Box it in. Lay a rope around the outermost points to form the smallest rectangle that contains the whole pool, then measure that rectangle's length and width.

Does a curved pool cost less than a rectangular one the same size? No. The cover is cut from the full rectangle that contains your pool, so a kidney pool with a 10m × 5m rope rectangle uses the same material as a 10m × 5m rectangular pool.

Do I need to measure my steps? Yes, separately. Record length, width, distance from one end, and which side — standing at the shallow end, calling it left or right. Steps are built into a single welded cover.

How do I measure an above-ground pool? Inside the wall at the waterline, not across the top rail. Record the wall height and top rail width as well, since these affect reel compatibility.

How accurate do my measurements need to be? Within 5cm is comfortable. Every cover is cut 150mm larger than your figures, so a few centimetres either way won't affect the fit. Take each dimension twice, and if two readings differ by more than 10cm, re-measure before ordering.

What's the difference between an upturn and a waterline cut? An upturn cut leaves a small raised margin that helps hold debris and allows for material movement. A waterline cut follows the water's edge exactly and sits flatter.

Does a debris cover get measured the same way? No. It anchors over the pool edge, so it's measured with a 200mm overlap on every side rather than to the waterline.

Do I need to tell you where the reel goes? Yes. The reel end determines which way the cover rolls, which affects how a step area folds and which reel suits your deck space.