Investment Calculator (Euro)
Project a euro-denominated portfolio with monthly contributions, tax and inflation.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
Enter an annual return, inflation rate and your own estimated tax rate. Tax is modeled as a single deduction from positive total growth at the end; this is not a country-specific tax calculation and excludes fees, timing of taxable events and product rules.
Worked example
calculated with the default values below
Starting amount 10,000 € · Monthly contribution 200 € · Expected annual return 7 % · Investment period 20 years · Tax on gains 0 % · Inflation 2 % Balance before tax 140,204.12 € · Total paid in 58,000.00 € · Investment growth 82,204.12 € · Tax on gains 0.00 € · Balance after tax 140,204.12 € · After-tax value in today’s money 94,353.35 € · Years for lump sum to double 10.2 years
Method and assumptions
The annual return is treated as an effective rate, with monthly rate (1 + r)^(1/12) − 1. Contributions are added at each month’s end. The entered tax rate is deducted once from positive total growth at the end, and inflation discounts that net balance. Euro is the currency, not a country tax regime; fees, tax timing and variable returns are excluded.
Data sources
Disclaimer
These calculators give estimates for general information only. They are not financial, tax or investment advice and do not take your personal circumstances into account. Before borrowing, investing or filing, confirm the numbers with a qualified adviser in your jurisdiction.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
B_{k+1} = B_k × (1 + r_m) + M; r_m = (1 + r_a)^(1/12) − 1
- B_k
- Balance after k months
- r_m
- Monthly rate
- r_a
- Annual return (%)
- M
- Monthly contribution (€)
- n
- Number of months
No annualized return is calculated because regular contribution timing is simplified. Tax is applied once to positive aggregate growth at the end.
Frequently asked questions
What assumptions does this model use? (Investment Calculator (Euro))
The annual return is treated as an effective rate, with monthly rate (1 + r)^(1/12) − 1. Contributions are added at each month’s end. The entered tax rate is deducted once from positive total growth at the end, and inflation discounts that net balance. Euro is the currency, not a country tax regime; fees, tax timing and variable returns are excluded.
Does a 20% tax input change a zero-return example?
With €1,000 initially, €100 at each month end, 0% return, 1 year and 0% inflation, both final and net balance are €2,200. Growth is zero, so even a 20% tax input deducts €0. For positive returns only positive growth is taxed once at the end.
Which inputs and limits apply to Investment Calculator (Euro)?
Use the units shown beside each field. These are form limits, not recommended settings. Starting amount: 0–5,000,000 €; Monthly contribution: 0–100,000 €; Expected annual return: -20–30 %; Investment period: 1–60 years; Tax on gains: 0–60 %; Inflation: 0–20 % The annual return is treated as an effective rate, with monthly rate (1 + r)^(1/12) − 1. Contributions are added at each month’s end. The entered tax rate is deducted once from positive total growth at the end, and inflation discounts that net balance. Euro is the currency, not a country tax regime; fees, tax timing and variable returns are excluded.
What is a complete worked example for Starting amount = 10,000 €; Monthly contribution = 200 €?
Inputs: Starting amount = 10,000 €; Monthly contribution = 200 €; Expected annual return = 7 %; Investment period = 20 years; Tax on gains = 0 %; Inflation = 2 %. Calculation: B_{k+1} = B_k × (1 + r_m) + M; r_m = (1 + r_a)^(1/12) − 1. Results: Balance before tax = 140,204.12 €; Total paid in = 58,000.00 €; Investment growth = 82,204.12 €; Tax on gains = 0.00 €; Balance after tax = 140,204.12 €; After-tax value in today’s money = 94,353.35 €; Years for lump sum to double = 10.2 years.