General rules
- Calculations run at full precision. Amounts are rounded to the nearest rupee only when they are shown, so totals can differ from the sum of the rounded rows by a rupee or two.
- Every number written in a page's explanations and examples is produced by the same code as the calculator, so text and results always agree.
- Each calculator is tested against worked examples before its page goes live, and the tests run again every time the site changes.
- Results are estimates before tax, fees and charges unless a page says otherwise.
Where rules and rates come from
We use sources in this order, and follow the official text when they disagree:
- The official scheme texts: the scheme notifications of December 2019 made under the Government Savings Promotion Act, 1873, and the Income-tax Act, 2025 as amended.
- Official amendments and orders issued since, such as India Post savings bank orders.
- Reputable news and financial websites, only where no official text is available.
Government scheme rates in use
The Ministry of Finance announces small savings rates every quarter. The calculators use the rates for Oct–Dec 2026, last checked on 7 October 2026.
| Scheme | Rate a year |
|---|---|
| Public Provident Fund (PPF) | 7.1% |
| Sukanya Samriddhi Account | 8.2% |
| Senior Citizens Savings Scheme | 8.2% |
| National Savings Certificate | 7.7% |
| Kisan Vikas Patra | 7.5% |
| Post Office Monthly Income Scheme | 7.4% |
Sources for these rates
- India Post, Post Office Small Savings Schemes interest rates w.e.f. 01.10.2026 to 31.12.2026 (official India Post rate table, checked 7 October 2026)
- https://www.business-standard.com/amp/finance/personal-finance/ppf-rate-unchanged-at-7-1-what-investors-need-to-know-this-quarter-126100200411_1.html
- https://www.caclubindia.com/articles/post-office-interest-rates-from-october-2026-check-the-latest-rates-of-all-schemes-56295.asp
- Jagran Josh, small savings rates October–December 2026
- https://www.bajajfinserv.in/investments/post-office-saving-schemes
- https://www.nsiindia.gov.in/
- Scheme limits: Gazette notifications of 12 Dec 2019 (G.S.R. 914-920(E); RD is G.S.R. 918(E)); SCSS ₹30 lakh per G.S.R. 240(E) 31 Mar 2023 (SB Order 06/2023, https://utilities.cept.gov.in/dop/pdfbind.ashx?id=7731); MIS ₹9/15 lakh per G.S.R. 239(E) 31 Mar 2023 (SB Order 07/2023, https://utilities.cept.gov.in/dop/pdfbind.ashx?id=7732)
Loans
EMI
EMI = P × r × (1 + r)n ÷ ((1 + r)n − 1)
The standard reducing-balance method: P is the loan amount, r the monthly rate (yearly rate ÷ 12 ÷ 100) and n the number of monthly instalments. Each month's interest is charged on the balance still owed. The rate is assumed fixed for the whole loan; fees and insurance are not included.
Investments
SIP
FV = P × [((1 + r)n − 1) ÷ r] × (1 + r)
P is the monthly instalment, r the yearly return ÷ 12 ÷ 100 and n the number of months. Each instalment is assumed to be invested at the start of the month, the usual convention in India.
Lumpsum
FV = P × (1 + r)n
A one-time investment compounded once a year at the yearly return r for n years.
Market-linked returns are not guaranteed. The SIP and lumpsum calculators show what a steady return would give; real returns go up and down from year to year.
Fixed deposit
A = P × (1 + R ÷ m)m × t
A cumulative deposit, where R is the yearly rate, m the number of times interest is compounded a year (quarterly by default, as most banks do) and t the term in years. Some banks pay simple interest on deposits shorter than six months; this calculator compounds throughout.
Government savings schemes
- PPF and Sukanya Samriddhi: each year's balance is (last year's balance + this year's deposit) × (1 + rate), compounded yearly. Each deposit is assumed to be made by 5 April, so it earns interest for the whole year. Sukanya Samriddhi deposits run for 15 years and the account matures 21 years after opening.
- SCSS: interest of deposit × rate ÷ 4 is paid out every quarter and is not compounded. The smaller first payment, which depends on the opening date, is left out.
- Post Office MIS: interest of deposit × rate ÷ 12 is paid out every month and is not compounded.
- NSC: compounded yearly and paid at maturity after 5 years.
- KVP: the amount doubles after a fixed number of months set by the government for each rate (115 months at the current 7.5%). The year-by-year values are indicative only.
Each scheme page lists all the scheme's rules — limits, early closure, loans, extension and tax — and the official sources they come from.
Last updated .