Simply enter the savings amount along with the savings account interest rates of your bank. Rest is automated. Keep in mind that most of the countries applies taxes on interest earning you can enter that percentage and calculations will be made with taxes taken in to account. The tax rate might also change according to the taxable amount or the tax brackets you are in. (married and having a joint account for example) Here taxable amount means the interest earned in a period, not the principle amount.
Interest calculations assumes the interest is added to your account balance at the end of each month. This way you can earn compound interest (interest of interest) You can see the numbers increasing more rapidly each month with the balance every month increased. Also need to mention that interest rates might change along the way. So take the numbers as guidelines. Also check other banks interest rates. You might prefer banks with introductory higher rates or less fees or compounding accounts (giving choice to automatically add the interest to the account every month or interest to main account principal stays as it is etc.)
Lets make an imaginary calculation. Assuming you have 50000$ in your savings account. If you use different currency doesn't matter because calculations works with ratios. Going with %1.7 interest rate and %10 tax for income over 10$. (these are close to real numbers in US currently) With this setup you earn 1552.64$ in 24 months (2 years) 172.52$ paid for taxes. Total money in your account at the end of 2 years is 51552.64$. Your first year earning will be 770.39$ and for second year 782.25$. If you can increase the interest rate to 2% total earnings will increase to 1831.39$ with 51831.39$ in your account at the end and tax payment will be 203.49$. 💸