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We show the formula, payment timing, rounding and omitted costs.
PERSONAL FINANCE WORKBENCH2026 EDITION
Before money moves, run the numbers.
Investing, loans & FIRE—
made measurable.
Not just an answer box. Every calculator shows the formula, assumptions and exclusions behind the result.
FIRESSEM / LEDGER 001YOUR NUMBERS, YOUR PLAN
Turn a distant goal into a planNumbers create
better questions.
better questions.
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Use any consistent currency unit.
Korea-specific tools are clearly marked.
01Investing
Compound Interest
Project a lump sum and monthly contributions with compound growth, including total contributions and investment gains.
02FIRE
FIRE Target
Calculate the monthly contribution needed to reach a financial-independence target by a chosen date.
03Stocks
Average Stock Price
Combine two stock purchases to calculate the weighted average price, total shares and total amount invested.
04Stocks
Loss Recovery
Find the gain required to recover from an investment loss and return to the original value.
05Saving
Deposit Interest
Estimate gross interest, tax, net interest and maturity value for a lump-sum deposit or monthly savings plan.
06Loans
Loan Payment
Estimate payments and total interest for amortized, equal-principal and interest-only balloon loans.
07Korea
Korea Severance Pay
Estimate statutory Korean severance pay from service dates and the previous three months of wages.
08Korea
Korea 3.3% Withholding
Split Korea’s common 3.3% freelancer withholding into income tax, local income tax and expected net payment.
Practical guidesPut the formulas
View all English guides →Put the formulas
into real situations
Financial independence, translated into a number
Find Your FIRE Number
Estimate a FIRE target from annual spending, then test how long your current savings plan may take to reach it.
8 min read →Why the second decade can matter more10 vs 20 Years of Compounding
Compare monthly investing over 10 and 20 years and see when growth begins to contribute more than new cash.
7 min read →Small rate, large lifetime differenceThe Cost of 1% More Interest
Compare monthly payment and total interest on a 30-year loan at 3%, 4% and 5%.
7 min read →The Firessem standardRead the conditions
Read the conditions
behind the result.
Explicit scope
Country-specific calculators are labeled and dated instead of presented as universal.
Private by default
Calculations run on your device. Your financial inputs are not stored by us.