Payback Period Calculator (Simple & Discounted)

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 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.