I have been given a formula for calculating a t test statistic as

$$t_{n-1} = \frac{ \bar{x}- \mu_0}{\frac{S}{\sqrt{n}}} $$

Where $\bar{x}$ is the sample mean, $\mu_0$ is the hypothetical true mean, $S$ is the sample standard deviation and $n$ is the sample count.

But when I plug my values in, the outcome is negative.

I don't see how to look up a negative value on the T-table. Should I be taking the absolute value?

[Update]

I am trying to follow the formula to get the t-statistic. The formula gives me a negative result but there is no entry in the t-table for a negative t-value. This is different from the Z-table which has 2 forms. Why does the Z-table have 2 forms but the T-table only one? I now understand that by convention I am meant to imagine the second form. However the formula only calculates one form.