How much should be deducted from the length and width when cutting glass to allow for expansion and contraction?

When cutting glass, it’s crucial to account for thermal expansion and contraction, which can occur due to temperature changes. Glass expands and contracts with heat and cold, and this can lead to potential stress or damage if it fits too tightly in the frame.

In this case, a deduction of 1/8" from both the length and width of the glass is appropriate. This slight adjustment allows for enough space to accommodate any variations in size due to temperature fluctuations without compromising the integrity or stability of the installation.

If the glass were cut too precisely without allowing for this expansion, it could lead to issues such as cracking or breaking, especially in environments where temperatures fluctuate significantly. This practice is a standard measure in the glass-cutting process, ensuring durability and long-lasting performance.

The other options present different deductions that, while they may accommodate some variations, do not align with the commonly accepted standard of 1/8". A smaller deduction could risk tight fitting, while a larger one could compromise the aesthetics and secure fit of the glass.