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This is a retirement fund calculator packed with only the essential features for those dreaming of Financial Freedom (FIRE).

Solve the question, "How much do I need to save to receive this much interest every month?" with just a single input.

It automatically reflects interest income tax of up to 15.4%, displaying pre-tax and post-tax amounts at a glance.

** Key Features

- Two-way Instant Calculation: Check 'Required Investment Principal' based on 'Desired Monthly Interest', and reverse calculate 'Monthly Interest to be Received' based on 'Investment Principal'

- Automatic Pre- and Post-Tax Breakdown: Automatically calculates interest income tax at 15.4% (14% Income Tax + 1.4% Local Income Tax) and displays pre-tax interest, tax, and post-tax interest all at once

- Annual Interest Rate Presets: Quick selection of 3%, 5%, 9%, 15%, and 20%, along with fine-tuning buttons for ±0.1% and ±1%

- Quick Amount Input: Easily input amounts using presets ranging from +100,000 to +10 million KRW

- Investment Style Guide: Provides text for investment style levels, ranging from safe savings deposits to index-tracking ETFs, based on the entered annual interest rate

- Korean Amount Display: Converts large amounts into an easy-to-read format like '○ billion ○ million KRW'

- Calculation History: Automatically saves and retrieves recent calculation results

- Data Backup: Supports full data backup and restoration

Recommended for:

- Economical For those planning retirement funds with the goal of FIRE

- For those who want to quickly know the investment principal required to receive the desired monthly interest

- For those who want to check in advance the monthly interest they will receive from their accumulated investment principal

- For those who want to accurately calculate the difference between pre-tax and post-tax interest

Accurate Calculation Formula
Required Investment Principal = Pre-tax Monthly Interest × 12 ÷ Annual Interest Rate
Post-tax Monthly Interest = Pre-tax Monthly Interest × (1 − 15.4%)
Automatic Calculation