Maximum size of input according to the time complexity and maximum number of operations
This table gives the maximum input size $n$ you can use with an algorithm of a given complexity according to the maximum number of operations/units of time allowed.
This of course does not take into account any leading coefficients or more complicated expressions of the time complexity, but it gives a rough estimate.
For instance, if an $\mathcal{O}(n\log n)$ algorithm is used with a maximum number of operations of 1,000,000, the input should not be greater than 88,000.
For every computation, the chosen base of the logarithm is $e$.