Coin1. What every calculator does
Each of our 34 calculators applies a published formula to the numbers you enter. The formula is printed on the calculator page under Formula & source, together with the rule or convention it follows, so you can reproduce the result by hand or in a spreadsheet. Calculations run entirely in your browser; your inputs are not sent to our servers.
- Tax calculators follow the Income-tax Act slabs, rebates, standard deduction and cess for FY 2026-27, as amended by the latest Finance Act.
- Small-savings calculators (PPF, Sukanya Samriddhi, SCSS, RD) use the interest rates notified by the Ministry of Finance for the current quarter and the scheme's own compounding rules.
- Investment calculators (SIP, lumpsum, step-up SIP, SWP) use standard future-value formulas with monthly compounding. The return rate is your assumption — market returns are not guaranteed.
- Loan calculators use the standard reducing-balance EMI formula that Indian banks use, assuming a fixed rate for the full tenure.
- Salary calculators use the statutory PF ceiling, gratuity formula (Payment of Gratuity Act, 1972) and current professional-tax and income-tax rules, with clearly stated default salary-structure assumptions.
2. Live data
Where a number genuinely changes every day, we pull it from a public feed instead of hard-coding it:
- Mutual fund NAVs — AMFI (Association of Mutual Funds in India), daily, after the evening nav publication. Used in: SIP, step-up SIP and lumpsum calculators (“Use a real mutual fund”).
- Foreign exchange rates — exchangerate-api.com open feed, daily. Used in: NRE FD calculator currency converter.
Bank FD rates and live stock prices are deliberately not shown: there is no single official feed for them, so calculators use clearly labelled assumptions you can change.
3. How we review and update
- Every Union Budget — tax, deduction and scheme rules are re-checked against the Finance Act and CBDT notifications, and every affected calculator is updated before the new financial year.
- Every quarter — small-savings interest rates are re-checked against the Ministry of Finance notification.
- Every page shows a review note (for example “Math verified for FY 2026-27”), and every guide shows when it was last updated.
- Corrections — if you find a number that looks wrong, tell us. We verify reports against the official source and correct the page.
4. How our guides are written
Guides in the CoinCalc Journal are written by the CoinCalc Team and checked against primary sources — the Income Tax Department, RBI, SEBI, AMFI, EPFO, PFRDA and India Post — which are listed at the end of each article. Worked examples are computed with the same formulas as our calculators. Rates that change often are given as ranges.
- We do not recommend specific funds, stocks, banks, insurers or apps.
- Partner links, where present, are labelled as such and never change a calculation or the order of results.
- CoinCalc is not a SEBI-registered investment adviser or an IRDAI-licensed broker. Everything here is educational — see the full disclaimer.
5. Formula and source for every calculator
The basis of each result, as shown on its page:
Investment
- SIP Calculator — Standard SIP future value formula (ordinary annuity, monthly compounding) (Math verified for FY 2026-27)
- Step-Up SIP Calculator — Step-up SIP formula with annual increment (Math verified for FY 2026-27)
- Lumpsum Calculator — Compound interest formula (annual compounding) (Math verified for FY 2026-27)
- PPF Calculator — Government of India quarterly notification; PPF Scheme 1968 (PPF rate per Govt notification for current quarter)
- Goal SIP Calculator — Reverse SIP solver (annuity present value) (Reverse annuity solver)
- Sovereign Gold Bond Calculator — RBI Sovereign Gold Bond Scheme; Section 47(viic) IT Act (Per RBI SGB Scheme)
- SWP Calculator — Standard SWP simulation; "4% rule" (Trinity Study adapted) (Standard SWP simulator (FY 2026-27))
Loans
- Home Loan EMI Calculator — Standard amortizing loan formula (used by all Indian banks) (Bank-standard amortization)
- Personal Loan EMI — Standard amortizing loan formula (Rates as of FY 2026-27)
- Car Loan EMI — Standard amortizing loan formula (Bank lending rates as of FY 2026-27)
- Loan Eligibility Calculator — Standard FOIR-based loan eligibility (FOIR-based eligibility)
- Stamp Duty & Registration Calculator — State Stamp & Registration Department notifications (State stamp acts for current FY (FY 2025-26))
- Rent vs Buy Calculator — Net-wealth comparison model (Indian context) (Net-wealth comparison model)
Tax
- Income Tax Calculator — Finance Act 2025, Income Tax Act 1961 (Updated for Finance Act 2025 (FY 2026-27))
- HRA Exemption Calculator — Section 10(13A), Income Tax Act 1961 + Rule 2A (Per Section 10(13A) and Rule 2A)
- Capital Gains Calculator — Section 111A, 112A; Finance Act 2024 (Per Finance Act 2024 (post 23 July 2024 rates))
- TDS Calculator — TDS provisions; Income Tax Act 1961 (TDS thresholds and rates for FY 2026-27)
- Advance Tax Calculator — Section 208–219; Income Tax Act 1961 (Section 208–219; FY 2026-27 slabs)
Salary
- CTC to In-Hand Calculator — Standard payroll structure (Indian employers) (Updated for FY 2026-27)
- Gratuity Calculator — Code on Social Security, 2020 (gratuity chapter; replaced the Payment of Gratuity Act, 1972) (Per the Code on Social Security, 2020 (in force from 21 Nov 2025))
- EPF Maturity Calculator — EPF Act 1952; EPS 1995; EPFO interest rate notifications (EPFO interest rate FY 2024-25 (8.25%))
GST & Business
- GST Calculator — CBIC, GST Acts 2017 (Per CBIC notifications, GST Act 2017)
- Profit Margin Calculator — Standard business mathematics (Standard business mathematics)
Deposits
- FD Calculator — Standard FD calculation; RBI guidelines (TDS rules per Section 194A)
- NRE FD Calculator — Income Tax Act Section 10(4)(ii); FEMA 1999 (Per Section 10(4)(ii); FEMA rules)
- RD Calculator — Standard RD calculation with quarterly compounding (TDS rules per Section 194A)
- Compound Interest Calculator — Standard compound interest formula (Standard compound interest formula)
- Senior Citizen Savings Scheme (SCSS) Calculator — Senior Citizens Savings Scheme, 2019 (MoF gazette); ₹30L limit per Budget 2023 (SCSS rate per Govt of India quarterly notification)
- Sukanya Samriddhi Yojana Calculator — Sukanya Samriddhi Account Scheme, 2019 (MoF gazette) (SSY rate per Govt of India quarterly notification)
Insurance & Retirement
- Term Insurance Calculator — Human Life Value method (insurance industry standard) (Human Life Value method)
- Retirement Corpus Calculator — Standard retirement planning (annuity present value) (Real-return method)
- NPS Calculator — PFRDA National Pension System; Section 80CCD (PFRDA rules; Sec 80CCD(1B) FY 2026-27)
Currency & Misc
- Inflation Calculator — Standard inflation/compound formula (CPI India FY 2024-25 base)
- 50/30/20 Budget Calculator — Elizabeth Warren, "All Your Worth" (Elizabeth Warren's 50/30/20)
6. Limits of any calculator
Results are estimates based on your inputs and the stated assumptions. They exclude product-specific charges, exit loads, changes in rates over time and individual tax situations that the calculator does not ask about. For decisions with legal or tax consequences, consult a qualified Chartered Accountant or a SEBI-registered Investment Adviser.