About / How we check
Method
How we check every number
A money site is only as good as its numbers. This page sets out where ours come from, the rules every calculator follows, the dated figures that change during the year, and what happens when we get something wrong.
Who checks
Everything on 37xBetter is written and checked by one person, a banker with more than nineteen years in Indian banking who holds the NISM Investment Adviser Level 1 and Level 2 certifications. The site is deliberately anonymous, so the About page lists the experience and credentials but not the name. Because you cannot check a name, the method on this page is what we ask you to judge us by.
Four rules for every figure
- No rupee figure goes up unless it has been computed. Every number in a guide, a comparison or a belief page is worked out either by the same code that runs the calculators or by a separate script, and the two are checked against each other before anything is published.
- Rules and rates come from the source. Tax rules, RBI and IRDAI rules, small-savings rates and EPF rates are checked against the government, regulator or official notification before we write them down, and never from memory.
- Every example states its assumptions. If a page says ₹10,000 a month becomes about ₹92 lakh, it also says the return assumed and the number of years, so you can rerun it with your own figures.
- We show the trade-off. Every comparison page has a section on when the other option is the better one, because most money choices depend on your situation.
How the calculators do the maths
Different instruments compound in different ways, and using the wrong method can move a result by lakhs, so each calculator follows the method its instrument actually uses:
| Instrument | How we compute it |
|---|---|
| SIP, step-up SIP, goals, retirement, NPS, SWP | The annual return you enter is treated as a yearly growth rate, and the monthly rate is worked out from it. So 12% a year runs as about 0.949% a month, which is lower than 12% divided by 12. |
| Home and other loans | The usual bank method: the yearly rate divided by 12, on a reducing balance, with the EMI fixed for the tenure. |
| Fixed and recurring deposits | Interest compounded every quarter, as most banks do. |
| PPF | Interest credited once a year at the rate the government has set. |
| Traditional insurance plans | Every premium and every payout laid out year by year, and the single yearly rate that balances them, which is the IRR. |
The defaults are chosen to be cautious and ordinary. Inflation is taken at 6% a year unless you change it, and the withdrawal (SWP) calculator and the Money Checkup use a 3% yearly withdrawal, which is lower than the 4% often quoted from American studies, for the reasons set out in the 3% rule guide.
The figures that change during the year
Some numbers on this site are set by the government or a regulator and change from time to time. These are the ones we track, with the date we last checked each:
| Figure | Value we use | Last checked |
|---|---|---|
| PPF interest rate | 7.1% for October to December 2026, set by the Ministry of Finance every quarter | 3 October 2026 |
| EPF interest rate | 8.25% for 2025-26, as declared by the EPFO | 29 September 2026 |
| EPF wage ceiling | ₹25,000 a month from 17 September 2026 | 29 September 2026 |
| NPS exit at 60 | At least 20% into a pension for non-government subscribers, 40% for government employees (PFRDA, December 2025) | 29 September 2026 |
| Equity long-term gains tax | 12.5% on gains above ₹1.25 lakh a year | 3 October 2026 |
| RBI inflation target | 4%, the target set for the period to 2031 | 29 September 2026 |
Small-savings rates are rechecked at the start of every quarter. When a figure changes, the calculators and the pages that quote it are updated together.
What we never do
We do not name a bank, an insurer or a fund as one to buy or avoid, we do not predict returns, and we do not sell anything. Nothing on the site pays us a commission. Examples use real plan structures, such as a guaranteed-income plan's actual premiums and payouts, with the product's name left out.
When we get something wrong
Mistakes happen even with checks. When one is found, by us or by a reader, we fix the page, recheck every other page that uses the same figure or rule, and update the "last reviewed" date on each page we change. In September 2026 a full review of every finance page on the site led to corrections on more than twenty pages, and the method on this page is what came out of it.
If you find a figure that looks wrong, write to hello@37xbetter.com with the page and the number. Every message is read.