Figuring out how much to save for retirement and when you can safely stop working can be difficult. A growing number of online retirement calculators, many of them free, are available to help. Although these calculators can yield vastly different results, they can be useful tools.

Based on information about you and your finances, calculators try to predict how much you need to save to achieve your retirement goals. Some calculators are web-based, and others require you to download a program or an app.

Retirement calculators can be useful, but you need to keep in mind that results can diverge significantly and they are not always accurate. It may be a good idea to use several different calculators to obtain a range of predictions.

Before getting started with any retirement calculator, you will need to gather information about your finances. Even the most basic calculator will want to know how much you currently have saved and how much you’re saving each month. More advanced calculators might require more detailed investment information.

Here are three sites that evaluate these financial tools:

• The website “Can I Retire Yet?” has a list of calculators with details about cost, platform and accuracy. See https://www.caniretireyet.com/the-best-retirement-calculators/
• The Balance provides its own assessment of what it considers to be the best retirement calculators. See https://www.thebalance.com/web-s-best-retirement-income-calculators-2388842
• Forbes shares information on five free retirement calculators, ranging from simple to the more complicated. See https://www.forbes.com/sites/robertberger/2015/07/12/5-excellent-retirement-calculators-and-all-are-free/#17a904dd4d1c