Simple ROI formula

Net profit equals ending value plus cash income minus other costs minus initial investment. Simple ROI divides that profit by initial investment. With R100,000 invested, R115,000 ending value, R12,000 income and R5,000 costs, profit is R22,000 and simple ROI is 22%.

The formula is transparent but has no time dimension. A 22% return over six months is not equivalent to 22% over five years. Always report the holding period beside simple ROI. Also state whether amounts are before or after tax, finance costs and inflation.

Ending value and income

Ending value is the asset or project value at the measurement date, whether realised through sale or estimated. Cash income includes distributions received separately, such as rent, dividends or project receipts not already in ending value. Double counting occurs if an account balance already includes reinvested income and the same income is entered again.

An unrealised valuation is uncertain and may exclude selling costs or market impact. Use a defensible valuation date and method. When comparing projects, apply consistent treatment of working capital, residual value and recoverable deposits.

Costs that are easily omitted

Other costs can include maintenance, transaction fees, professional charges, insurance, platform fees, rates, vacancy, marketing and disposal costs. Initial investment should include setup amounts required before returns begin. Financing interest may be included or excluded depending on whether the analysis measures project performance or equity return.

Write a scope note. An unlevered project ROI and leveraged shareholder ROI answer different questions. Comparing one after finance with another before finance is misleading. Tax should also be modelled consistently, using advice where deductions, depreciation and capital gains are material.

Annual-equivalent rate

The page calculates an annual-equivalent rate by taking final wealth divided by initial investment to the power of one over years, minus one. This is a compound growth rate only under the simplifying assumption that net income and costs can be treated at the end. It is not a true money-weighted return when cash flows occur throughout the period.

Use the number for a rough equal-period comparison after confirming that timing differences are minor. If rent arrives monthly, construction costs occur in stages or new capital is added, list dated cash flows and calculate XIRR. A single annualised figure can otherwise reward projects merely for moving cash dates.

Payback period

Simple payback divides initial investment by average annual net cash income, where net cash income is entered income minus costs spread evenly across the holding period. It ignores ending resale value, tax, financing, time value and changes in yearly cash flow. If net cash income is not positive, the result says payback is not reached.

Payback can be useful for liquidity screening but not for total value. A project with rapid payback may have weak later returns, while a long-lived asset may create value after a longer recovery period. Combine payback with NPV, risk and strategic constraints.

ROI versus IRR and NPV

Internal rate of return is the discount rate that sets net present value of dated cash flows to zero. Net present value discounts each cash flow at a required return and reports value in rand. These methods recognise timing in ways simple ROI cannot, but IRR can be ambiguous with unusual sign changes.

Use a discount rate consistent with risk and funding opportunity. A positive NPV at that rate indicates value above the required return under the forecast. No metric repairs unrealistic cash-flow assumptions, so document volumes, prices, operating costs and terminal value.

Inflation and real return

The calculator uses nominal rand amounts. If a project spans several years, price inflation can increase revenue, costs and ending value while reducing purchasing power. A nominal ROI should be compared with a nominal required return. A real analysis should remove expected inflation consistently from cash flows and discount rate.

Do not simply subtract inflation from a multi-year simple ROI. Compound relationships and cash timing matter. For a rough annual comparison, convert nominal annual return to real using (1 + nominal) divided by (1 + inflation) minus one.

Risk and scenario ranges

One forecast hides uncertainty. Build downside, central and upside cases for income, costs, delay and ending value. Identify variables that can make final wealth non-positive or breach cash constraints. A high expected ROI may be compensation for a meaningful chance of loss.

Check concentration, liquidity, counterparty, regulatory and operational risk. An asset that cannot be sold quickly should not be compared with cash using only average return. Record who supplied each assumption and the date it was last verified.

Business and personal decisions

For a business project, include incremental cash flows caused by the decision, not costs that occur regardless. Treat staff time, capacity and working capital consistently. For personal property or education decisions, some benefits may be non-financial and should be described separately rather than assigned an invented rand value.

A negative calculated ROI does not automatically make a safety, compliance or essential-care expense wrong. Conversely, positive private profit does not capture environmental or social cost. The metric supports a defined financial question; it does not replace judgement about every consequence.

Audit trail

Save initial amount, dates, income statements, cost evidence and valuation support. Recalculate from realised cash flows after completion and compare with forecast. Separate forecasting error from execution difference. That learning improves later decisions more than reporting only the successful headline percentage.

When presenting ROI, include formula, period, cash-flow scope, tax basis, valuation status and whether the figure is simple or annualised. Avoid saying return without those qualifiers. Another reader should be able to reproduce the number and identify excluded items.

Use consistent cash-flow boundaries

List exactly which inflows, operating costs, taxes, fees and residual value are included, and keep financing cash flows separate when comparing projects. Apply the same time horizon and price basis to every option. A high percentage calculated from an incomplete cost base should not outrank a lower but fully documented return.