Interest calculator

Advanced tool for calculating appreciation of investments & visualisation of investment strategies.

Alpha version. Interest calculator is in development.

Currency: Currency for count
Basic deposit: Initial investment amount in selected currency.
Annual interest rate: Targeted or reached annual interest in percentages.
Investment period: Investment length in selected time period.
Compound interval: Frequency of crediting interest. Interest is always credited at the end of compond interval.

Example: There is investment of $100 with fixed annual interest of 10%. At the ned of first year, our revenu is interest 10% of $100 -> $10. Another year later, interest is still 10%, however, this time from $110 ($100 of basic deposit + $10 from first year of investment). 10% of $110 is $11 -> total investment value is $121 now. Interest value in next years will be $133, $146, $161, $177, $195. Take into notice, that your interest is nearly 100% of deposit already after first 7 years of active investment.
Regular There is possible to increase / decrease value of investments by additional deposits / withdraws. (If this is considerable as an investment, all deposits and withdrawals should be scheduled to a more periods for averaging values and eliminating risks of sudden deflections. This tool allow work with regular ddeposits/withdrawals throughthrought all investment time.

How this interest calculator works with deposits / withdrawals:
Regular hits as deposits and withdrawals are function of compound interval. This tool considers filled numbers as 1 investment with set prametres. Deposits/withdrawas are then function of Compound interval. If frequency of deposits / withdrawals is higher than frequency of compond interval, the deposited funds / withdrawed funds are not counted in interest - the funds are not evaluated.
Examples:There is $1,000 funds value at the start of periode. Annual interest is 10%. Monthly withdrawal is set to $10. Because of annual interest, and monthly withdrawal, calculator cnsider active investment value of $880 ($1000 - 12 * $10). Final interest is then $88 only. If the withdrawal would be on yearly basis, processed after interest count, withdrawed money would remain same ($120), but active funds would be $1000 instead of $880. An investor would have final interest $100, and funds at the end of this periode would be $980 instead of $880. It's 10% of whole investment balance!.

In a case of deposits, with annual interest and regular monthly deposits, there is no change in the interest after end of the year periode. Sum of regular deposits made in interest period is counted at the start of next period. (This is only case of this tool and example counts, in real, where all investment are not counted as a whole - P2P lendings, assets..., there is definitely good to use regular deposits on lower timeframe.)
Annual inflaction rate: Inflation is a case when money lose their value. Usual annual inflation rate is 2-3%. Simply explained, every year, there is possible to buy for same amount of money 2-3% less goods. Inflation is the opposite case of compound interest. Check detailed explanation of inflaction on Wikipedia.

Inflation rate is calculated always at the end of compound interval via a deduction of current investment value. Example: If there is 2% of annual rate, calculator makes cut of 2% of invetsment value (current investment value * 0.98). By this way, final amount at the end of investment does not respect real amount of money at the end, but real value of money.
Fill red values. Move hover underlined keywords for help.

TOTAL SUMMARY Currency for count

Duration Deposit Interest Inflation Balance *Evaluation*


values in

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How to use the calculator

Interest Calculator page (this app) is composed from 4 sections displayed in following order:

  1. Input section
  2. Graph section
  3. Data table
  4. Documentation

Section 2,3 are passive sections for displaying results. Only section for interaction is section 1, alternatively additional buttons with advanced options (for saving, exports, discussion) below section 3.

Section 1 - "Input section" is composed from 2 tabs:

  • Count interest - for counting interest on basis of filled values
  • Load from storage - for listing between saved counted variations

Both sections display additional descriptions of all their underlined terms. This description is displayed after clicking at the underlined terms.

Quick Summary graph

Detailed Results graph

How it works

Purpose of the interest calculator

Definition of financial terms


Compound interest

Interest calculator was created for simple counting and visualisation of investments. The tool allows working with common interest, compound interest

How to count interest

About compond interest. (Wikipedia) Tool as an app

Interest calculator is part of education game about money and economy. Read about the project at website.