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These tools cover the cost of borrowing and the value of saving. A loan or mortgage calculator shows the monthly payment, the total interest, and how much of each payment goes to principal — usually the number people are actually looking for. The savings and retirement tools work the other way, projecting what regular contributions grow into.

Interest in Tanzania is normally quoted as a monthly rate on a reducing balance, which is not the same as an annual rate divided by twelve; the loan interest guide sets out the difference. Rates, fees and insurance requirements vary by lender, so treat every result as an estimate of the particular offer in front of you.

The two ways of quoting interest are what make loan offers hard to compare. A flat rate is charged on the full amount borrowed for the whole term, so a 20% flat rate over two years costs far more than a 20% reducing-balance rate over the same period — the reducing-balance charge is worked out on what is still owed, which falls every month. Two lenders quoting the same percentage can therefore be offering loans that differ substantially in cost, and the only honest comparison is the total interest each one charges.

Fees and insurance sit outside the interest rate and are easy to miss when comparing offers: arrangement or processing fees, a mandatory insurance premium on the financed amount, valuation and legal costs on a mortgage, and sometimes a ledger fee. On a mortgage in particular, the deposit plus these upfront costs is the cash needed before anything is borrowed, and it is usually the number that decides whether a purchase is possible.

Which calculator to use

Finding the monthly payment and the true cost

Use the Loan Calculator for a repayment figure and the total interest over the term, and the Mortgage Calculator for a property purchase — it takes the deposit and term a bank will ask about, and shows how much of each payment is principal and how much is interest.

Deciding whether you can afford the payment

Use the Loan Affordability Calculator. Working from an income and existing obligations it estimates the payment a lender would judge manageable, which is a more useful starting point than picking a term and hoping the payment fits.

Comparing two offers that quote interest differently

Use the Loan Calculator twice — once for the flat-rate offer and once for the reducing-balance one — and compare the total interest and the total repaid rather than the headline rate. The loan interest guide works through the arithmetic.

Projecting savings, or what a lump sum becomes

Use Compound Interest for a savings or investment projection, Inflation to see what a future amount is worth in today's money, and Retirement for what regular contributions build up to. The UTT calculator covers unit trusts specifically, with its assumed returns labelled as illustrative targets.

Group savings and borrowing

VICOBA and SACCOS work on different conventions from a bank loan — contribution cycles, share multiples, and interest calculated on a reducing balance over the cycle. The VICOBA and SACCOS guide sets out those conventions, and its figures are generated from the same engine the calculator uses.

Common mistakes here

  • Comparing a flat rate with a reducing-balance rate as if the percentages were equivalent. At the same nominal rate the flat-rate loan costs roughly twice as much interest, because it is charged on the original amount for the whole term.
  • Dividing an annual interest rate by twelve to get the monthly rate a lender quotes. Tanzanian lenders quote the monthly rate directly; the monthly figure on a reducing-balance loan is not simply the annual rate over twelve.
  • Budgeting for the deposit and forgetting the upfront costs. On a mortgage the valuation, legal fees, insurance and stamp duty are paid before drawdown, and they are a real part of the cash needed.
  • Treating an illustrative investment return as a promise. The UTT tool's assumed returns are targets published as such, not guarantees, and they are labelled that way wherever they appear.
  • Reading a debt-to-income ratio as a rule set by the Bank of Tanzania. It is a rule of thumb lenders apply differently; the tool shows the arithmetic, not a regulatory limit.

Worked examples

  • What flat and reducing-balance interest actually cost

    On a 10,000,000 TZS loan quoted at 12% over 3 years, a flat-rate lender charges 3,600,000 TZS in interest (377,778 TZS a month), while the same 12% on a reducing balance costs 1,957,152 TZS (332,143 TZS a month) — so the flat loan's true annual cost is about 21.2%, not 12%.

Calculators

Guides

Maintained by David M at Delta Tech Solutions · Figures last checked 26 September 2026 · Next check due 26 March 2027