Cost
Fibreglass is generally cheaper. The shell is factory-moulded, so on-site labour is lower - a fibreglass pool commonly runs $30,000 to $90,000 installed. Concrete is built in place and fully custom, so it costs more, commonly $55,000 to $150,000 or more.
Important nuance: excavation and site costs are driven by soil type, not shell choice. The shell-price difference is real, but it is not the whole budget.
Timeline
Fibreglass is faster. Once council approval is through, a fibreglass shell install commonly takes 4 to 8 weeks. A custom concrete pool is a 12 to 22 week build on site. If having your yard back sooner matters, fibreglass wins on timeline.
Customisation
Concrete wins on freedom. A concrete pool can be any shape, size or depth, with custom steps, ledges and features. Fibreglass shells come in set shapes and sizes - there is a wide range, but you are choosing from a catalogue rather than designing from scratch.
Lifespan and finish
Both are long-life structures. A fibreglass shell's gelcoat finish is durable and low-maintenance. A concrete pool's interior finish - render, pebble or tile - is renewed over time, which is resurfacing work. For resurfacing an existing pool, our sister site Pool Resurfacing Adelaide specialises in exactly that.
How to decide
There is no universal winner. Fibreglass suits a faster, lower-cost build from a catalogue of shapes. Concrete suits a fully custom design where you control everything and accept the higher cost and longer build. The Pool Builders Adelaide network includes fibreglass-only, concrete-only and dual builders, so you can get real quotes for both and compare.