Kidney vs Figure 8 pools compared
Kidney vs Figure 8 pool, side by side: figures at the same nominal size, strengths, trade-offs and a straight recommendation.
Both of these shapes give up straight walls entirely and commit to curves — no corners, nothing a level and a set square would draw. Where they part ways is what the curve is doing. The kidney is one continuous gesture: a single bean-shaped sweep with a waist that narrows for looks, not for function. The figure-8 pinches that same waist until it becomes a real doorway between two roughly circular lobes — the kidney reads as landscape, the figure-8 reads as two rooms.
What doesn't differ is worth saying first. Neither shape offers a straight swim lane worth the name — both lose a genuine chunk of their length to their curves, the same rule that applies to any free-form pool. Both need curved formwork, cut-to-shape coping and a custom cover; neither takes a standard rectangular anything. Both circulate beautifully, because neither has a true corner for water to stall in. What differs is whether the curve is one flowing line or two, and whether the narrowing in the middle is decoration or a genuine boundary.
- size of the figure-8's second lobe relative to its first — the waist does the zoning, not a size gap
- ≈75%size of the figure-8's second lobe relative to its first — the waist does the zoning, not a size gap
- of straight swim length either free-form shape gives up to its curves
- ≈ 1/3of straight swim length either free-form shape gives up to its curves
- smallest box each shape ships as — the figure-8 needs a little more room to pinch a waist without squeezing either lobe
- 6×3.5 vs 7×4 msmallest box each shape ships as — the figure-8 needs a little more room to pinch a waist without squeezing either lobe
- typical shell premium curved, free-form walls carry over a straight-walled pool of the same water area
- +15–30%typical shell premium curved, free-form walls carry over a straight-walled pool of the same water area
Kidney
The free-form classic — a pool that looks grown, not built
Strengths
- Blends into planting like no straight shape can
- The waist creates two natural zones
- No corners: excellent circulation
Trade-offs
- No straight swim lane
- Curved formwork and coping raise build cost
Figure 8
Two lobes, one pool — a playful silhouette with built-in zones
Strengths
- Two clearly separated zones in one basin
- Friendly, distinctive silhouette
- The waist naturally hosts a rail or crossing point
Trade-offs
- The waist interrupts any swim lane
- Complex curves raise forming and coping cost
At a glance
| Kidney | Figure 8 | |
|---|---|---|
| Nominal size | 8 × 4 m | 8 × 4 m |
| Water surface | 18.2 m² | 19.1 m² |
| Volume | 27.6 m³ | 26.5 m³ |
| Perimeter | 18.6 m | 18.2 m |
| Footprint efficiency | 57% | 60% |
One curve, or two rooms
The kidney's waist is a visual event, not a wall. Look at the bean from above and both ends stay in full view of each other across the narrow part — nothing actually stops a swimmer, a pool toy or a wave from crossing it. It's there to invite planting, a boulder or a slide at the narrowest point, and to keep the eye moving along one unbroken line.
The figure-8's waist is doing a different job. It pinches between two roughly circular lobes — the main one close to the pool's full width, the second running a good deal smaller, maybe three-quarters its size — until the gap between them is genuinely narrow. That narrows enough water to matter: put a rope, a rail or just a change in depth across it, and you've built two rooms that share one filter, not one room with a wobble in it.
Swimming and play: what the waist buys you
Neither shape is for laps. The kidney offers no straight line worth calling a lane; the honest description is a pool for bobbing, floating and informal play, and — like any curved shape — it loses roughly a third of its length to the bend, so draw it a size up from what the straight-line number in your head suggests.
The figure-8 can't offer laps either, but it offers something the kidney can't: two usable circular spaces instead of one long, unusable bean. The bigger lobe genuinely hosts swimming, splashing and a few real strokes across its width; the smaller one is naturally shallow-friendly — steps, small kids, a spa corner. If the household actually needs to keep two groups apart rather than just look like it does, that's the figure-8's whole argument.
How each one sits in the garden
The kidney disappears into naturalistic, tropical and retro mid-century gardens better than almost any other shape. Its single flowing boundary lets planting reach the water on the outside of the curve, hides the pool's true size, and makes a small garden feel bigger because the eye never finds a straight edge to measure it against.
The figure-8 is still all-curve, so it blends with planting too — but its two-lobe identity reads as more deliberately designed, less purely organic. It earns its keep in a garden that already has two different jobs to do: a sunny lounging corner and a shadier play corner, say, which the pool can then physically underline instead of just implying. The practical test: do you want the pool to vanish into the garden as one shape, or do you want it to visibly organise two different activities? That question is basically the whole decision.
Building the curves
Both shapes cost a genuine premium over straight walls — curved shuttering, steel bent to radius, and coping cut piece by piece to follow the line, typically in the region of 15–30% over a straight-walled pool of equal water area. Neither shape gets a shortcut here.
The figure-8 carries one extra local difficulty the kidney doesn't: the waist is a tight, compound curve where two circles meet, and that pinch point wants real care in both the shuttering and the steel. The kidney's curve, by contrast, is one continuous sweep with no internal joint at all — arguably the more straightforward of the two curved shapes to form, even though both sit well above a rectangle on price. Liner pools shift the arithmetic a little: the kidney is a common stock pattern for many manufacturers, while a figure-8 liner is more often a bespoke order.
Covers and cleaning
Neither shape has the rectangle's fallback of a standard cover, or even the L-shape's option of splitting into two rectangular pieces — a kidney or a figure-8 always takes one custom cover, built to a template of the exact pool. Budget the time for that fitting as much as the money.
Cleaning rewards both shapes for having no corners: the kidney's single sweep gives water nowhere at all to stall. The figure-8's waist is the one spot worth watching — not a corner, but a narrows, and a rail or net placed across it without circulation in mind can leave a small eddy on each side. Aim a return inlet through the gap and it stays as clean as the rest of the pool. Both are still far easier to keep clear than a sharp-cornered rectangle.
Choose the kidney if… choose the figure-8 if…
Choose the kidney if the goal is landscape beauty on its own terms — an informal, planted or retro garden, one flowing gesture, nothing that needs to physically keep people apart.
Choose the figure-8 if you genuinely need to separate two groups — small kids from adults, swimmers from loungers — if you want a real spot for a rail or rope, or if a friendly two-lobe silhouette simply suits the garden better than a single bean.
If you're undecided, draw both at the same overall length in the designer. The moment you see the figure-8's waist pinch between two distinct circles against the kidney's one uninterrupted sweep, the choice usually makes itself.
Both are playful free-forms; the kidney reads as one flowing gesture, the figure-8 as two rooms with a doorway. For zoning kids and adults, the figure-8's waist genuinely works; for pure landscape beauty, the kidney's single curve is stronger.
Frequently asked questions
- Can I swim real lengths in either shape?
- No — neither offers a straight lane, and both give up roughly a third of their length to curves. For actual lap swimming, look at a rectangle or one of its softened variants instead.
- Does the figure-8's waist really keep kids and adults apart?
- It genuinely narrows the water, so a rope or rail across it works as a real boundary — unlike a kidney's waist, which only narrows the view, not the water. It's still a soft boundary, not a fence, so supervise as you would any zoned pool.
- Which is cheaper to build?
- Similar territory — both are curved and custom-covered at roughly the same premium over a straight pool. The figure-8's waist adds one extra tight joint to form, which can nudge it slightly above a kidney of the same water area, though site conditions usually matter more than this difference.
- Can either pool use a liner instead of concrete?
- Yes, but the kidney is the more common stock liner shape across manufacturers; a figure-8 liner is more often made to order.
- Which shape makes a small garden feel bigger?
- The kidney, slightly — its one continuous curve hides the pool's true size better than a shape with a visible internal pinch, though both beat a hard-edged rectangle on this point.
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