Resources:Stapplet to perform a 1-sample T interval for a mean: https://www.stapplet.com/quant1v_single.html
You'll see One Quantitative Variable, Single Group. Name the variable
Select an input: Either "Raw data" or "Mean and standard deviation"
Input in the data or stats depending on your selection then click on "Begin Analysis"
Perform Inference: Select "1-smple t interval"
Input the confidence level and click on "Perform inference".
Output shows the t statistic, the p-value and df, the degrees of freedom.
If you need to calculate a critical value for t, this is the best calculator I found