Roblox numbers are generally stored as 64-bit floating-point values, so they can go from about −1.7×10308-1.7\times 10^{308}−1.7×10308 to 1.7×103081.7\times 10^{308}1.7×10308, but they only stay precise for about 15 digits.

For whole numbers, Roblox also has narrower integer types in some places: int is 32-bit, and int64 goes up to 263−12^{63}-1263−1, which is about 9.22 quintillion.

What that means in practice

  • For normal scripting, you can usually use very large numbers without hitting the hard limit.
  • For exact big integers, precision becomes a problem after about 2532^{53}253, so values above that may not be counted exactly.
  • If you are using an IntValue, the safe max is about 9.22 quintillion.

Simple example

If you set a value to 1000000000000000, Roblox can handle it, but once numbers get much bigger, it may start rounding instead of keeping every digit exactly.

TL;DR: Roblox can represent numbers up to about 1.7×103081.7\times 10^{308}1.7×10308, but exact integer precision is only reliable up to about 9 quadrillion for Number math and about 9.22 quintillion for IntValue-style integers.