Calculator Methodology
Every calculator on CoinMind runs on a published, standard formula. This page documents which formula each tool uses, the official source we verify against, what the calculator deliberately excludes, and when it was last checked.
All calculations run in your browser using JavaScript. We do not guess, approximate, or use black-box algorithms. Where a calculator shows a worked example, the numbers come from the same formula the tool uses.
SIP Calculator
Formula
Future value of annuity: FV = P × [((1+r)^n − 1) / r] × (1+r)
Official source
Standard financial mathematics; cross-checked against AMFI SIP data
Excludes
Exit loads, fund-specific expense ratios, market timing risk
Last verified
July 2026
EMI Calculator
Formula
Reducing-balance EMI formula: EMI = P × r × (1+r)^n / ((1+r)^n − 1)
Official source
Standard amortisation formula used by all Indian banks per RBI guidelines
Excludes
Processing fees, prepayment penalties, floating rate changes
Last verified
July 2026
Income Tax Calculator
Formula
Marginal slab rates per Income Tax Act, Section 87A rebate, standard deduction
Official source
Income Tax Department, Government of India — incometaxindia.gov.in
Excludes
Surcharge above ₹50L, marginal relief, professional tax, specific deductions beyond standard
Last verified
July 2026 (FY 2026-27 slabs)
FD Calculator
Formula
Compound interest: A = P × (1 + r/n)^(n×t) with quarterly compounding
Official source
RBI guidelines on fixed deposit interest calculation
Excludes
TDS on interest above ₹40,000 (₹50,000 for seniors), premature withdrawal penalties
Last verified
July 2026
PPF Calculator
Formula
Annual compounding on minimum balance between 5th and last day of month
Official source
Public Provident Fund Scheme rules, Ministry of Finance / National Savings Institute
Excludes
Loan and partial withdrawal rules, interest rate changes (currently 7.1%)
Last verified
July 2026
NPS Calculator
Formula
Future value of growing annuity with equity/debt split projections
Official source
PFRDA guidelines, NPS Trust
Excludes
Annuity rates at maturity (varies by provider), tier-2 account features
Last verified
July 2026
GST Calculator
Formula
Add: base × (1 + rate/100). Extract: inclusive / (1 + rate/100)
Official source
Central Board of Indirect Taxes and Customs (CBIC)
Excludes
Input tax credit, reverse charge, composition scheme
Last verified
July 2026
EPF Calculator
Formula
Annual compounding on monthly contributions at declared EPF interest rate
Official source
EPFO — epfindia.gov.in
Excludes
EPS (pension) component, insurance benefits, withdrawal rules
Last verified
July 2026
Educational use only
These calculators are educational tools to help you understand financial concepts. They are not a substitute for professional financial, tax or investment advice. For decisions that materially affect your money, confirm current figures with a qualified professional.