Additionally, this calculator looks at how much of your current income you expect to need to live on when you retire, and for how long. This requires some more guesswork on your part (and maybe a little daydreaming?). Long says that 70% to 80% of your annual salary is the industry standard estimate, but that of course changes depending on your plans. If you'd prefer to live extremely frugally and become a coupon queen, that percentage can drop. Have plans to travel around the world and buy a castle? You'll need to significantly increase that amount. This number will likely change as you get closer to actually thinking about stopping work, Long explains, so stick to 80% now for a more conservative estimate.