Monthly Income from Capital Calculator
Compute approximate monthly income from invested capital, given net annual rate. Useful for "live off interest" planning.
Perpetuity yield on a managed portfolio
This calculator answers the classic "live off interest" question: how much income does capital C generate at net annual rate r, withdrawing only the yield so principal stays intact? Annual income is Y = C · r; monthly income is M = C · r / 12. This is a perpetuity in financial-math terms — the present value of a constant infinite cash flow is PV = M / i, hence M = PV · i.
Example: R$ 500,000 at a net 8% per year (typical for a diversified portfolio after taxes and fees) produces R$ 40,000 per year, or about R$ 3,333 per month. To safely pull R$ 10,000 monthly net (R$ 120,000/year) you need roughly R$ 1.5 million at the same 8%. The rate matters: at 10% net you'd need R$ 1.2 million; at 5%, R$ 2.4 million. Inflation is the silent killer of perpetuity strategies — if you spend the full nominal yield, real purchasing power decays at the IPCA rate (around 4% per year in Brazil).
Robo-advisors and managed portfolios in Brazil
Platforms like Magnetis, Vitreo (Empiricus), Warren, and Rico Inteligente automate diversified allocation across Tesouro, CDB, FIIs, and equity funds. Management fees range 0.3%–1.0% per year, versus passive ETFs (BOVA11, IVVB11) at 0.03%–0.20%. The fee gap compounds: 1% per year over 30 years removes roughly 26% of final wealth (0.99^30 ≈ 0.74). For a long-term perpetuity goal, low-fee passive allocation usually wins; managed services pay off when behavioral discipline (auto-rebalancing, tax-loss harvesting) outweighs the fee. The 4% safe withdrawal rule (Trinity Study, 1998) was calibrated for US 60/40 portfolios; in Brazil's higher real-rate environment 5%–6% has historically held over 30-year windows.
FAQ
What does "net rate" mean here? It's the yield after income tax, management fees, and custody. A 110% CDI gross at 15% Selic and 22.5% IR gives roughly 12.8% net; subtract 0.5% management and you're at 12.3% net. Always plug the post-everything number.
Why is monthly income just yearly divided by 12? The calculator uses a simple proportional split, common in financial planning. Strictly, monthly compounding would give a tiny premium — at 8% annual, the equivalent monthly is 0.643%, so R$ 500k × 0.00643 = R$ 3,216 (not R$ 3,333). The simple division overstates monthly income by ~3% at typical rates.
Does FGC cover this kind of portfolio? Only the CDB and LCI/LCA slices, up to R$ 250,000 per CPF per institution. Tesouro is backed by the Treasury (not FGC). Stocks, FIIs, and equity funds have no deposit insurance — they're market risk.
What happens if I withdraw more than the yield? Principal erodes and the timeline becomes finite — that's the depletion calculation, not perpetuity. Run both numbers before committing to a withdrawal strategy.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.