Aquarium Glass Thickness & Pressure Reference
This page estimates the water pressure on your aquarium’s panels and a reference minimum glass thickness using the same engineering approach as classic DIY aquarium charts (annealed glass, safety factor 3.8). It exists to help you sanity-check a plan and understand the physics — not to certify a build.
Pressure & reference thickness
The physics: pressure grows with depth, fast
Water pressure on a panel depends only on depth: P = ρgh. At 50 cm depth that is ~4.9 kPa — modest per square centimetre, but integrated over a 120×50 cm panel it becomes roughly 150 kg-force pushing outward. Because pressure rises linearly with depth, the load on a panel grows with the square of water height, and required glass thickness grows with height to the power 1.5. This is why tall tanks get thick and expensive quickly: doubling tank height nearly triples the required thickness.
Where the thickness formula comes from
The estimate models a vertical strip of the panel as a beam simply supported at top and bottom under the triangular hydrostatic load — the standard conservative simplification behind long-published DIY aquarium glass charts. It uses the industry design figure of 19.2 N/mm² tensile strength for annealed float glass, divided by a safety factor of 3.8, the conventional choice in aquarium references because glass is brittle, variable and often scratched in service. For panels much longer than they are tall (the common case), this strip model is realistic; for short panels supported on all four edges it is conservative — the true requirement is somewhat lower. A braced top edge reduces bowing, reflected here as a modest 15% reduction.
What the calculator cannot know
- Glass condition: scratches, chipped edges and poor cutting concentrate stress and dramatically reduce real strength. Polished edges matter.
- Tempered vs annealed: tempered glass is ~4× stronger but cannot be drilled or cut, and fails explosively into fragments rather than cracking. Most aquarium panels are annealed; check before drilling anything.
- Seams and silicone: most real-world tank failures are seam failures, not panel breakage. Seam quality is pure workmanship.
- The stand: a twisted or unsupported stand loads corners the math assumes are supported. Rimless tanks need flat, planar support with a foam mat; framed tanks need supported perimeters.
Frequently asked questions
Is a safety factor of 3.8 overkill?
No. Published guidance treats SF 2 as the bare minimum for a perfect panel in perfect conditions, and 3.8 as the standard for real tanks that get scratched, moved, and unevenly supported over years. Commercial rimless tanks sometimes run lower factors with premium glass and controlled manufacturing — a DIY build should not.
Does tank length change the thickness requirement?
For panels longer than about twice the water height, barely — each vertical strip carries its own load, which is why charts group by height. Length matters enormously for bowing and seam stress though, which is why long rimless tanks use eurobracing or thicker stock than the strip model demands.
Can I use this for acrylic?
No. Acrylic has completely different mechanics (it flexes far more, creeps under sustained load, and is usually bonded rather than siliconed). Acrylic thickness tables are separate — consult an acrylic fabricator.
What about the bottom panel?
The bottom sees uniform pressure but usually rests on the stand (or on plastic frame edges), so it works in bearing rather than bending. Standard practice is bottom glass equal to or one step thicker than the sides — and for rimless tanks, a full flat support surface underneath. Follow your builder’s or supplier’s spec.