How we build and check these calculators

This site publishes financial calculators and guides for India and a handful of other countries. Money content is only useful if the arithmetic is right and the rules behind it are current, so this page explains exactly how each number on the site is produced, where the rates come from, and what to do when you find a mistake.

Who writes this

Gurjeet Singh

Gurjeet builds Expense Tracker Income Manager, the offline expense and budget app this site accompanies, and runs Sharpen Solutions. The calculators here grew out of that work: the same formulas the app uses to project a balance, split a bill or schedule an EMI are the ones published on this site.

Contact: support@expenseincomemanager.com — every message is read.

How a calculator is built

  1. The formula comes first. Each calculator states the formula it uses in plain algebra, with every variable named. If a calculator cannot show its formula, it does not belong on this site.
  2. The worked example is generated by the page's own code, not written by hand. The numbers you see in the example are what the calculator returns for those inputs. (A hand-written example drifts away from the code the first time anything changes — in September 2026 we found about 25 pages where exactly that had happened, and fixed them.)
  3. Assumptions are stated, not hidden: compounding basis, rounding, day counts, and what the calculation deliberately leaves out.
  4. The maths runs in your browser. The amounts you type are never sent to this website or anywhere else. The site measures page views with analytics, as nearly all websites do, but your figures are not part of that.

Where the rates and rules come from

Statutory figures — tax slabs, deduction limits, TDS rates and thresholds, GST rates, small-savings interest rates, stamp duty and registration fees — are taken from the department that sets them, not from other websites. Typical sources include incometax.gov.in, cbic.gov.in and gst.gov.in, EPFO, the Reserve Bank of India, and the state registration departments; for non-Indian pages, the equivalent authority such as the IRS, gov.uk, canada.ca, the ATO or IRAS.

Where a page quotes a statutory figure — a tax slab, a rebate, a deduction limit, a GST rate, a small-savings rate, a contribution ceiling — it links the department page that states that figure, and the label on the link carries the date that source itself advertises. Every one of those links was opened and read before it was published. Calculators that are pure arithmetic — an EMI, a CAGR, a split bill, a currency conversion — quote no statutory figure and carry no source, because inventing one would tell you nothing.

Some figures carry no link, and that is deliberate. A few departments’ rate charts refuse automated access — incometaxindia.gov.in, the Australian Taxation Office and the US Social Security Administration among them — and we will not publish a link we could not open and check. Where that happened the page states the rule in words and names the department. Where an official source is old or undated, the page says so rather than implying the figure is current.

When we cannot verify a number, we do not print one. Several pages describe a rule in words and link to the department instead, because no official source published a figure we could stand behind.

How often it is checked

When we get it wrong

Mistakes in money content matter, so corrections are not quiet. If you find an error, email support@expenseincomemanager.com with the page and what looks wrong. We check it against the official source, fix it, and update the page's last-reviewed date the same week. If the error could have changed a decision — a tax rate, a duty, a deadline — the page says what changed and when.

What this site is not

These calculators are estimates to help you plan. They are not financial, investment, tax or legal advice, and they cannot see your full circumstances. For a decision that matters, check the figure with the department concerned or a qualified professional before you act on it.

This site earns nothing from the calculators. There are no ads, no affiliate links and no sponsored placements anywhere on it. It exists to be useful to the same people who use the app.