Running a business means more than handing the numbers to the accountant. Buying equipment means working out the payback period, renting a new shop means calculating rental yield, hiring means budgeting salary and MPF, and every year brings a tax bill to plan for. Whenever someone says "let me run the numbers", the first instinct is usually to open Excel.
The problem is starting from scratch every time. One row dragged wrong and nobody notices, a new file overwrites the old one and nobody knows which version is current, and colleagues are too nervous to touch a sheet full of VLOOKUP formulas. The same question ends up with different answers depending on who calculates it.
Yet these five categories of numbers already have calculators built for them: type a few figures, get a result, and understand how to read it. Below is when to use each one, what to enter, and finally an introduction to the Hong Kong built toolbox FinKit (finkit.hk), whose 27 tools are free to use in the browser.
1. Mortgage calculator: work out three numbers before buying
Most owners looking at a property ask "how much per month". The real question has three parts:
- How much deposit is needed, whether cash reserves cover it, and how much working capital is left afterwards.
- What the monthly repayment is, and what share of monthly net cash flow it consumes.
- Whether the business can still afford it if interest rates rise by two percentage points.
The third one is the one most people skip. Hong Kong's stress testing exists precisely to check whether repayments remain affordable after a rate rise. Running the numbers with a plus two percent scenario is far more useful than staring at a quotation. FinKit's mortgage calculator returns the monthly payment, total interest and amortisation schedule, and recalculates instantly when you change the term or rate.
2. Three tax calculators: salaries tax, profits tax, personal assessment
Every filing season the same thing happens: you know a bill is coming, but not how big. By the time the demand note arrives, cash flow is short and money has to be found in a hurry.
One estimate mid-year is enough to set money aside. The three to keep separate are:
- Salaries tax: your own salary and director's fee.
- Profits tax: company profits, noting the two-tiered rates.
- Personal assessment: combining salary, profits and rental income to see whether this method produces a lower bill.
Which one wins depends on how income is structured. Running each calculator and comparing the figures side by side is clearer than a verbal summary. FinKit's three calculators follow Hong Kong's tax rules, with local bands and options.
3. Cash flow: trend matters more than the bank balance
A bank balance shows today, not three months from now. Plenty of businesses look cash-rich yet suddenly cannot pay a bill, usually because of timing differences between money in and money out.
Cash flow control depends on consistent recording rather than a year-end catch-up. The simple approach works: log income and expenses daily or weekly, then review the trend once a month to see which months bleed cash. FinKit's automated expense tracker supports recurring entries, category totals and monthly reports, which suits small shops that do not want to learn accounting software.
4. Rent or buy: three formulas, one comparison
"Rent or buy" is the question SME owners ask most and find hardest to answer. Three sets of numbers make it concrete:
- Rental yield: annual rent divided by property price, showing the return if purchased.
- Rent versus buy: deposit opportunity cost, repayments, management fees and rent, all in one view.
- Refinancing: comparing total interest under the old and new rates.
These take half a day in Excel and ten minutes in a calculator. The important part is writing the assumptions down: will rent rise, will rates rise, how long do you plan to hold. Change an assumption and the conclusion can flip, so testing several scenarios is worthwhile.
5. MPF and retirement: owners are employees too
Many owners handle staff MPF meticulously while their own retirement plan keeps slipping. Once you know how much to put aside each month, the target often looks closer than expected.
FinKit includes an MPF calculator and a retirement savings goal calculator. Enter current age, existing assets, expected return and desired monthly spending in retirement, and it returns the monthly saving required. The FIRE calculator is there too, for anyone curious how far they are from work being optional.
What is FinKit?
Every tool mentioned above comes from FinKit (finkit.hk), a finance calculator platform built in Hong Kong. Three things stand out:
- 27 tools across 8 categories: personal finance, property, investing, tax, retirement, credit, foreign exchange and protection, from mortgages to IPO valuation.
- Local rules: tax bands, MPF caps, mortgage stress testing and rates are all Hong Kong figures, so there is no need to hunt for them elsewhere.
- Works in the browser: no software to install, no account, no company details required. Head straight to the tools list and pick what you need.
For an SME the most practical habit is bookmarking the handful you actually use: mortgage, profits tax, rental yield and the expense tracker. Next time a project, lease or machine purchase comes up, run a scenario in the calculator instead of opening a new spreadsheet, and never worry about a colleague using the outdated template.
Three steps to start
- Open finkit.hk/tools and pick a category.
- Enter the figures. Every field is explained, and there is no harm in testing with blank values first.
- Screenshot or note the result together with the assumptions, so the next scenario can be compared fairly.
Summary
There is nothing wrong with Excel. The problem is rebuilding the sheet every time and having no way to spot an error. Mortgages, tax, cash flow, rent versus buy and retirement are all cases of "fixed formula, changing numbers", exactly what a dedicated calculator is for.
Let the tools do the arithmetic and keep your time for the business. To try them all in one place, open finkit.hk, start with the one or two you need most, and bookmark the rest later.