50/30/20 Monthly Budget Calculator

Enter property price, down payment, term and rate — get monthly payment, total interest and total payable.

Compute Ad Valorem Stamp Duty (AVD) on residential property at the latest rates.

Estimate Hong Kong salaries tax using both the progressive bands and the 15% / 16% two-tier standard rate (Year of Assessment 2024/25).

Hong Kong MPF contributions for employees, employers and self-employed persons using the statutory 5% rate with the $7,100 minimum and $30,000 maximum relevant income thresholds.

Project the future value of a principal plus regular monthly or yearly contributions at a given annual rate, with total interest earned.

Compute the compound annual growth rate from a start value, end value and number of years — useful for comparing long-term growth.

Compute total profit, ROI % and annualised return from initial cost, final value and holding period — useful for comparing investments.

Project the future purchasing power of an amount given an annual inflation rate and time horizon — and the nominal amount needed to keep up.

Convert between cost, selling price, markup % and gross margin % — handy for retail pricing and SMB profit analysis.

From fixed costs, variable cost per unit and selling price, find the units needed to cover all costs — plus break-even revenue, contribution margin, target-profit volume and margin of safety.

Convert a nominal annual rate (APR) at any compounding frequency to the effective annual yield (APY), or solve the inverse — essential for comparing credit-card, savings-account and mortgage rates.

Quickly estimate how many years to double your money at a given compound rate, or what rate is needed to double in a target period — with the exact logarithmic answer alongside.

From balance, monthly payment and APR, compute how many months until the loan is paid off, the total interest paid, and the minimum payment that just covers interest.

Given goal amount, current savings, monthly deposit and APR, see how many months it takes to hit the target.

Enter principal, annual rate and number of periods to compute the fixed annuity payment (PMT formula) — essential for retirement-income planning.

Enter the after-tax salary you want to take home and the calculator works back to the gross figure you need to offer (HK MPF and salaries-tax aware).

Enter property price, monthly rent and yearly expenses (rates, management, insurance, vacancy) to see both gross and net rental yield (%).

Enter annual dividend per share, share price, EPS and amount invested to compute dividend yield (%), payout ratio (%) and projected yearly income.

Enter a price and a tax rate to compute the gross total and tax amount, or work backwards from a tax-inclusive price to the net amount.

Enter property value and loan amount to get the LTV ratio, the required down-payment, and a live check against HKMA caps and the HKMC mortgage insurance ceilings.

Discount a future amount back to today using an annual rate, horizon and compounding frequency — get the present value, discount factor and effective annual rate.

Use the Fisher equation to strip inflation from a nominal rate and find the real return, with the common r ≈ i − π approximation alongside.

Apply the Trinity Study 4% rule: enter your retirement nest egg and a withdrawal rate to see the annual and monthly income it can support.

Enter monthly debt payments and gross monthly income to compute your DTI ratio against the standard lender bands (36% / 43% / 50%).

Enter principal, annual rate and term and apply I = P × r × t to find the interest earned or owed under simple-interest accrual (no compounding).

Enter the initial outlay, future cash flows and a discount rate to compute the project Net Present Value (NPV) — positive NPV means the project beats your required return.

Enter the upfront investment, projected yearly cash flows and a hurdle rate to solve for the discount rate that makes NPV = 0 — and see at a glance whether the project beats your required return.

Enter your portfolio annual return, the risk-free rate and the annualised standard deviation to compute the Sharpe ratio — excess return earned per unit of risk taken.

Compare your current mortgage against a new rate, net of refinance closing costs and penalties, to find how many months to break even and whether the whole loan saves or costs more over its lifetime.

From face value, coupon rate, yield-to-maturity, years to maturity and coupon frequency, compute a fixed-coupon bond's present price, premium/discount and current yield.

Compute the future value of a stream of equal payments (e.g. monthly savings or pension contributions) with end- or beginning-of-period timing.

Enter the market values of equity and debt, the cost of equity, the cost of debt and the corporate tax rate to compute the weighted-average cost of capital (WACC), capital-structure weights and after-tax cost of debt.

Enter a company's net income, preferred dividends and weighted-average common shares outstanding to compute basic EPS, with an optional dilutive-securities input for diluted EPS.

Enter a fixed amount per period and the buy price for each period to see total invested, total shares, average cost and current value — with a side-by-side comparison against putting the same money in as a lump sum at the first price.

Enter account size, per-trade risk percent and stop-loss distance to compute the share/lot quantity that caps your loss at the chosen risk.

Enter several debts (balance, APR, minimum payment) and your monthly extra budget; the tool runs the classic "smallest balance first" snowball method, estimating each debt's payoff month, total interest paid and total months to debt-free.

Enter an initial investment, level annual cash inflow, discount rate and horizon to instantly see the simple payback period, the discounted payback period and the terminal Net Present Value (NPV), plus a year-by-year cumulative cash-flow table — built for capital-budgeting, small-business investments, solar installs and equipment purchase decisions.

Enter your current salary, raise percentage or dollar amount and instantly see your new salary plus annual, monthly, weekly and hourly differences — handy for comparing offers, negotiating reviews and gauging inflation-adjusted raises.

Enter a target amount (FV), expected annual return and term — the tool back-solves the periodic payment you need to reach that target, the classic "how much to save monthly to hit $X by year Y" question.

Enter the level periodic cash flow C and the discount rate r — the tool returns the perpetuity present value PV = C / r and, optionally, the growing-perpetuity Gordon value PV = C / (r − g) used for consols, preferred shares and dividend-discount models.

Enter the loan amount, the number of discount points bought and the rate reduction per point — the tool returns the upfront cost, the monthly payment saving and the break-even month so you can decide whether paying points is worth it.

Enter net operating income (NOI) and total annual debt service (principal + interest); the tool reports the debt service coverage ratio DSCR = NOI / debt service — the headline risk metric banks use when underwriting commercial property loans, business loans and investment-property mortgages.

Enter a share price and EPS — the tool returns the price-to-earnings ratio P/E, the earnings yield (EPS ÷ price), and the PEG ratio (if a growth rate is supplied), then puts the result in context with typical industry bands.

Enter total liabilities and shareholders' equity to get the D/E ratio, equity multiplier and debt-to-assets ratio, with industry context (utilities, tech, banking) to flag whether the firm's capital structure is conservative or aggressive.

Enter next year's dividend D₁, the required return r and the perpetual growth rate g; the Gordon dividend-discount model returns the intrinsic price P = D₁ / (r − g) and the growth rate implied by today's market price.

Enter net income, revenue, assets and equity; the tool applies the 3-factor DuPont identity to decompose ROE = Net Margin × Asset Turnover × Equity Multiplier, so you can see whether high returns come from profitability, efficiency or leverage.

Enter current assets (cash, receivables, inventory) and current liabilities (short-term debt, payables) to get the current ratio = CA ÷ CL, with industry-standard thresholds (< 1 warning, 1–2 healthy, > 3 idle cash) to flag short-term solvency at a glance.

Enter cash, marketable securities, receivables and current liabilities; the tool returns the quick ratio = (CA − inventory − prepaid expenses) ÷ CL, a stricter view of liquidity than the current ratio because it excludes inventory and prepayments that may not convert to cash quickly.

Enter net income and shareholders' equity (beginning / ending / average); the tool returns ROE = net income ÷ equity with the conventional bands (< 5% weak, 10–15% healthy, > 20% excellent), so you can read management's efficiency at deploying equity capital at a glance.

Enter share price and book value per share (or total equity + shares outstanding); the tool returns P/B = price ÷ book value and benchmarks it against typical banks, insurers, real estate and SaaS bands — a core value-investing screen used since Benjamin Graham.

Enter annual demand D, ordering cost per order S and holding cost per unit per year H; the tool applies the Wilson formula Q* = √(2DS / H) to return the optimal order quantity, order frequency and total inventory cost — the classic recipe for stock-keeping and supply-chain planning.

Enter operating income (EBIT) and total revenue; the tool returns the operating margin = EBIT ÷ revenue, then benchmarks the result against software, branded consumer, manufacturing, retail and airline norms — the cleanest single read on core operating efficiency.

Enter the risk-free rate Rf, expected market return Rm and the stock's beta β; the CAPM formula r = Rf + β·(Rm − Rf) returns the required rate of return (cost of equity) and breaks out the equity risk premium component (ERP × β).

Enter annual cost of goods sold (COGS) and average inventory; the tool returns the inventory turnover ratio (Turnover = COGS ÷ Avg Inventory) and days inventory outstanding (DIO = 365 ÷ Turnover) — the standard lens for retail, manufacturing and e-commerce to gauge stocking efficiency and working-capital tie-up.

Enter a series of periodic returns and a target return (often 0 or the risk-free rate); the tool returns the Sortino ratio = (R̄ − T) ÷ DD, where DD is downside deviation — a risk-adjusted return measure that captures only "bad" volatility (often preferred over the Sharpe ratio) — and annualises it based on the chosen frequency.

Enter portfolio return, risk-free rate and beta; the tool returns the Treynor ratio = (Rp − Rf) / β — excess return per unit of market (systematic) risk. It is the β-based analogue of the Sharpe ratio and is favoured for evaluating diversified portfolios and fund managers.

Enter days inventory outstanding (DIO), days sales outstanding (DSO) and days payable outstanding (DPO); the tool returns the cash conversion cycle — the number of days between paying suppliers and collecting from customers, a key measure of working-capital efficiency.

Enter the P/E ratio and the expected annual EPS growth rate (%); the tool returns the PEG ratio = P/E ÷ growth, popularised by Peter Lynch — a more honest valuation read for growth stocks than the P/E alone.

Enter EBIT and interest expense; the tool returns the interest-coverage ratio (also called Times Interest Earned) — a core credit metric used by rating agencies and lenders to judge a firm's ability to service its debt.

Enter your entry price, target and stop-loss; the tool returns the reward-to-risk ratio and the minimum win-rate required to break even — the headline check every trader runs before sizing a position.

Paste a price or NAV series and the tool returns the maximum drawdown (MDD), peak, trough, drawdown duration and recovery time — the benchmark downside-risk metric for any strategy.

Enter the optimistic (O), most-likely (M) and pessimistic (P) estimates; the tool applies the PERT beta-distribution formulas E = (O + 4M + P)/6 and σ = (P − O)/6, and reports the 1σ / 2σ / 3σ confidence ranges for project duration or cost.

Enter face value, coupon rate, years to maturity and current market price; the tool bisects for the bond's yield to maturity (YTM), current yield and total coupon cash flows — the discount-rate benchmark used in bond pricing, credit-spread analysis and retirement-portfolio planning.

Enter net operating income (NOI) and property value to get the capitalization rate (NOI ÷ value). The tool also solves in reverse — give it any two of {cap rate, NOI, value} and it derives the third — the standard yardstick real-estate investors use to compare property yields.

Enter face value, coupon rate, term, payment frequency and yield-to-maturity; the tool returns the Macaulay duration (the cash-flow-weighted average years to maturity) and modified duration (the % price drop for a 1 % rise in yield) — the standard measures of a bond's interest-rate risk.

Enter gross monthly income, existing monthly debt, mortgage rate and term; the tool applies the lending-industry 28 / 36 rule to estimate the maximum PITI you can afford and the corresponding home price — a universal pre-shopping affordability screen.

Enter current salary or pension, the year-over-year change in CPI and the COLA formula to apply; the tool returns the inflation-adjusted new amount and real purchasing power — used for contract renewals, pension uplifts and year-on-year comparisons.

Enter the standard deviation of daily, weekly or monthly returns; the tool applies the √N rule σ_annual = σ_period × √N to give the annualised volatility — the standard preprocessing step for Sharpe ratio, option pricing and risk reports.

Enter two price–quantity pairs; the tool applies the midpoint (arc) formula Ed = (ΔQ ⁄ Q̄) ⁄ (ΔP ⁄ P̄) and classifies demand as elastic, unit-elastic or inelastic — a staple of microeconomics, pricing decisions and tax-incidence analysis.

Paste a series of values (prices, sales or any time-series) and a window length N; the tool returns the simple moving average point-by-point via SMA_t = (x_{t−N+1} + … + x_t) ⁄ N — staple of technical analysis, demand smoothing and KPI dashboards.

Enter a tax-exempt bond yield (e.g. US municipal bonds) and your marginal tax rate; the tool applies TEY = tax-free yield ⁄ (1 − tax rate) to give the equivalent pre-tax yield a taxable bond must offer to match it — the standard yardstick for comparing investments with different tax treatments.

Paste a list of incomes / wealth / sales values; the tool computes the Gini coefficient via G = Σ|xᵢ − xⱼ| / (2 n² · mean) (0 = perfect equality, 1 = total inequality) and reports the Lorenz curve and cumulative distribution — used in economics, sociology and sales-concentration analysis.

Enter your essential monthly expenses and target coverage (3, 6 or 12 months); the tool returns the total emergency fund target, the gap from your current balance and the months needed to reach the target at your monthly savings rate — a cornerstone of personal-finance and FIRE planning.