Glass Thickness Calculator
Calculate the minimum safe glass or acrylic thickness for your DIY aquarium. Includes bracing requirements and panel weight estimates.
Panel Weight Breakdown
Bracing Requirements
At 48" long, a center brace is needed to prevent the front and back panels from bowing outward under water pressure.
Euro-bracing is optional for tanks 48" and under, but it adds rigidity and a polished look.
Safety Warning
These calculations provide minimum thickness guidelines based on standard engineering formulas. Always consult with a professional glass fabricator for large or custom tanks. Use tempered glass for tanks over 40 gallons. Ensure all seams use 100% silicone aquarium sealant (not kitchen/bath silicone). A failed tank can release hundreds of pounds of water and cause serious property damage.
How It Works
This calculator uses a simplified bending stress formula to determine the minimum glass or acrylic thickness needed to safely contain water pressure. The calculation accounts for hydrostatic pressure, which increases linearly with depth.
Safety factors are built into the formula: 3.8x for glass and 2.5x for acrylic. Glass has a higher safety factor because it is a brittle material that fails suddenly, while acrylic deforms before breaking, giving warning signs.
Bracing is critical for longer tanks. Water pressure pushes outward on the front and back panels, and without a top brace, the glass can bow and eventually crack at the silicone seams. Euro-bracing (a glass lip around the top perimeter) is the gold standard for tanks over 48 inches.
The calculator rounds up to the nearest standard glass thickness available from suppliers (6mm, 8mm, 10mm, 12mm, 15mm, 19mm, 25mm). Always use the standard thickness that meets or exceeds the calculated minimum.
Frequently Asked Questions
What type of glass should I use for a DIY aquarium?
Standard float glass (annealed) is most commonly used for aquariums. Tempered glass is stronger but cannot be drilled and shatters into small pieces if it fails. For tanks over 40 gallons, consider low-iron (starphire) glass for better clarity. Never use plate glass, window glass, or glass with imperfections -- these can have stress points that lead to catastrophic failure.
Is acrylic better than glass for aquariums?
Acrylic is about 50% lighter than glass, 17x more impact-resistant, and provides better insulation. However, it scratches more easily, yellows over time with UV exposure, and costs more. Acrylic is generally preferred for very large tanks (over 100 gallons) where weight is a concern, and for tanks that might experience impacts (children, high-traffic areas).
What silicone should I use to seal a DIY aquarium?
Use only 100% silicone sealant that is specifically labeled safe for aquariums. Common brands include GE Silicone I (not II), ASI Aquarium Silicone, and Momentive RTV108. Never use kitchen/bath silicone, as it contains anti-mold additives (fungicides) that are toxic to fish. Apply silicone in a continuous bead and allow 48-72 hours of cure time before filling.
Do I need to add bracing to my DIY tank?
Tanks longer than 36 inches should have a center top brace to prevent the front and back panels from bowing under water pressure. Tanks over 48 inches benefit significantly from euro-bracing -- a glass rim around the entire top perimeter that distributes stress. Bottom bracing or a flat, level stand is essential for all tanks to prevent point-loading that can crack the bottom panel.