Calculators can give you an idea of your life expectancy (the time remaining from your current age) based on your current age, gender, and several other important lifestyle choices. Calculators are used widely by financial and insurance companies for planning purposes as well as by non-professionals, like you, for general well-being strategy and planning.
With few exceptions most calculators are based on data collected in US or Canada over a period of a couple of decades. Life expectancy results reveal very little about normal process of aging, and associated quality of life.
The results are averages and should not be accepted as fact or fate. It is very unlikely that anyone will live exactly as long as any calculator predicts.
The best way is to use the results only as an inspiration to value your remaining time, not to convey certainty.
Here are links to a few of the many on-line calculators that are in the public domain:
US Social Security Administration is a barebones calculator, Living to 100, Blueprint Income, and Project Big Life all offer suggestions and strategies to up your longevity game, and finally Poodwaddle’s Life Clock wants to remind you to stop wasting your remaining time.