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Aquarium Glass Dimensions Calculator
Aquarium Glass Dimensions Calculator — Cut List for Custom Tanks
Building a custom glass aquarium requires precise glass cut dimensions to ensure the panels fit together correctly when assembled with silicone seams. The key challenge is that glass panels overlap each other at the corners — for example, the front and back panels in a standard build run the full external length, while the side panels fit between them. The bottom panel fits inside all four side panels. If you order glass cut to the wrong dimensions, the panels won't align and your silicone joints will be uneven or under stress. This calculator takes your desired internal dimensions, glass thickness, and silicone seam thickness and outputs the exact cut dimensions for every piece. Use this list when ordering from a glass shop — they need individual piece dimensions, not the assembled tank size. Glass shops typically cut in millimeters, so this calculator uses millimeters as input.
How to Use This Calculator
1
Measure or decide your desired external tank dimensions in millimeters.
2
Select your glass thickness — see the Glass Thickness Calculator to determine minimum safe thickness first.
3
Enter the silicone seam width — typically 2mm. This is the gap between glass edges that silicone fills.
4
Click Generate Cut List and give the exact dimensions to your glass shop.
5
When ordering, specify the glass type (float glass vs. low-iron/ultra-clear) and ask for polished edges on all cuts for safety and aesthetics.
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Frequently Asked Questions
Should I use standard float glass or ultra-clear glass?
Standard float glass has a greenish tint visible at the edges, which doesn't affect water viewing much in thin panels but becomes noticeable in thick glass (10mm+). Ultra-clear (low-iron, Starphire) glass is optically clear with no green tint and is the choice for high-end display tanks. It costs 2–3× more but makes a significant visual difference.
What silicone should I use?
Use 100% silicone labeled 'aquarium safe' or 'aquarium grade'. GE Silicone I (clear, not the anti-mold version) and Dow Corning 732 are industry standards. Never use silicone with mildewcide, anti-bacterial agents, or 'kitchen and bath' varieties — these contain fungicides toxic to fish.
Do I need a glass brace on top?
For tanks longer than 30 inches, a center brace (euro-brace or H-brace) across the top is strongly recommended. It prevents the glass from bowing outward under water pressure, which would open the silicone seams. The Glass Thickness Calculator accounts for whether the tank is reinforced or not.
Can I build a saltwater reef tank from tempered glass?
Tempered glass is very strong but cannot be cut or drilled after tempering. Order tempered panels with any needed holes pre-cut. Tempered glass is preferred for the bottom panel for safety. The front and back panels of display tanks are often non-tempered so you can drill bulkheads later if needed.
