Disclaimer

The general position

Every calculator on Calcrivo applies a documented formula to the numbers you enter. It does not know your circumstances, it cannot see anything you have not typed, and it cannot tell you whether a decision is a good idea. It produces an estimate, and an estimate is a starting point for a conversation with someone qualified — not a substitute for one.

We also make mistakes. Formulas are covered by automated tests (see Methodology), but tests only catch what they are written to catch. If a result looks wrong, it may be wrong: please tell us.

Tax calculators

Tax is the area where the gap between a model and reality is widest. These calculators:

• use the rates, bands and thresholds for a stated tax year, which may have changed since the page was last reviewed;
• model the main reliefs and allowances for a straightforward case, and omit the long tail of credits, exemptions and anti-avoidance rules that apply to particular situations;
• generally do not model interactions between national and regional/state/provincial tax, nor local levies;
• know nothing about your other income, your filing status beyond what you select, prior-year positions, or anything carried forward.

Treat the output as an order-of-magnitude check. For anything you will file or pay on, use the official calculator published by the relevant tax authority, or an accountant.

Loans, mortgages, pensions and investments

• Repayment and amortisation figures assume the interest rate, term and fee structure you enter stay fixed. Real products reprice, and variable rates move.
• Affordability and borrowing-capacity results are arithmetic on your inputs. They are not a lending decision, a pre-approval, or an indication of what any lender will offer — lenders underwrite on criteria we cannot see.
• Investment and retirement projections compound an assumed rate of return that you supply. Future returns are unknown; a projection is a what-if, not a forecast. Inflation, fees, taxes and sequence of returns will all change the outcome, and most calculators model only those you enter.
• Nothing on this site is a personal recommendation to buy, sell or hold any financial product, and Calcrivo is not a regulated financial adviser.

Health and fitness calculators

These implement published population-level formulas — body mass index, estimated energy requirements, heart-rate zones, pregnancy dating and similar. Two consequences follow directly:

• They describe populations, not individuals. A population formula can be misleading for a particular body: BMI, for instance, does not distinguish muscle from fat and is known to misclassify athletes and some ethnic groups.
• They are not a diagnosis, a screening test, or a treatment plan, and they do not account for your medical history, medication or symptoms.

Discuss anything that concerns you with a doctor, midwife or other qualified clinician. If you think you may be having a medical emergency, contact your local emergency services rather than a calculator.

Construction, electrical and engineering calculators

These apply standard sizing and load formulas, and several reference code-derived values such as ampacity tables or derating factors. They are design aids for people who already know the subject. They are not a substitute for the current edition of the applicable code, for local regulations and inspection, or for a qualified engineer’s sign-off, and material quantity outputs make no allowance for waste unless the page says so.

Work that must be certified — structural, electrical, gas, drainage — must be designed and signed off by someone competent and appropriately licensed to do it.

Conversions, maths and reference calculators

Unit conversions, geometry, statistics and the programmer/networking tools are deterministic: given the same inputs they give the same answer, and the answer is correct or it is a bug. The practical caveats are rounding at the displayed number of decimal places, and definitional ambiguity in a few units — US versus imperial gallons, short versus metric tons — where the page states which one it uses.

Live data and exchange rates

Where a calculator shows a currency exchange rate or similar market-derived figure, it is indicative and may be delayed. It is not a dealing rate: the price you are actually offered will include a spread and fees. Do not use it to settle a transaction.

Country-specific pages

Country and state versions of a calculator exist where the underlying rule genuinely differs — a different tax band, a different minimum wage, a different registration fee. They carry the figures for that jurisdiction as at the page’s review date. Rules change on legislative timetables we do not control, so check the current official figure before relying on it.

External sources

Where a page cites an official source, the citation is there so you can verify the figure at source. We link only to sources we can point at exactly; where no such citation is given, the formula is a standard one and the page explains it in full instead.

Reporting an error

If a calculator gives a result you believe is wrong, please report it with the inputs you used and the figure you expected. That is the single most valuable thing anyone sends us, and it is how the catalog gets corrected.