Calculators At Westpac, we love helping you achieve your goals. You’ve already thought of the ‘what if’. Now let’s figure out the ‘when’. Which could give the best return? Use this calculator to work out what you could earn after tax for different savings and term investment options. Saving for a goal Calculate how much you need to regularly save to reach your goal. How long will it take You know what you can afford to regularly save, find out how long it will take to reach your goal. Budget calculator Before you can 'stick to your budget', you need to set one. Let's run some figures and get a handle on things.