A savings goal without a monthly number is a wish. These guides work backwards from the target and the deadline to the amount you need to set aside each month, and show what happens when you shorten or stretch the timeline.
How to use these guides
Work from the deadline backwards, which is what these guides do: the target divided by the months gives the monthly number, and that number is the only test of whether the goal is real. If it does not fit alongside your existing commitments, change the deadline rather than abandoning the goal.
Keep goal money separate from the account you spend from. A recurring deposit or a separate savings account removes the decision each month.