We just shipped 17 new finance calculators — full Groww parity, all client-side
From XIRR to APY to Sukanya Samriddhi Yojana — Stax now covers every calculator on Groww's catalog, with the same math but zero server-side processing of your numbers.
We just shipped 17 new financial calculators in a single batch, bringing Stax's finance category to parity with Groww's calculator suite — the de facto standard reference for Indian retail investors. Same math, same currency formatting, same default values informed by FY 2025–26 government rates. The difference: every calculator runs entirely in your browser. Your salary, your loan amount, your portfolio cash flows — none of it touches a server.
Here's what we added, organized by what they actually solve.
Investment & mutual fund calculators
Lumpsum Calculator — Future value of a one-time investment. The simplest tool in the bunch, but the one that makes the compounding curve visceral: ₹1 lakh invested at 12% for 30 years grows to ~₹30 lakh, almost entirely from compounding.
SWP Calculator — Systematic Withdrawal Plan modeling. Critical for retirement planning. Shows whether your corpus survives the chosen tenure at the chosen monthly draw, or runs out early. The 4% safe withdrawal rate myth (sustainable in the US, often unsafe in India given inflation) becomes obvious once you run the numbers.
Mutual Fund Returns Calculator — Combo of SIP + lumpsum. Toggle between modes to compare the two approaches for the same total investment. For most salaried investors, SIP wins on discipline; for windfalls, lumpsum captures more compounding.
Step Up SIP Calculator — SIP with annual increases. The single most under-used calculator. ₹10k/month flat SIP for 25 years at 12% gives you ₹1.9 cr. Same SIP with a 10% annual top-up gives you ₹3.7 cr. The step-up percentage matters enormously over long horizons.
Stock Average Calculator — Weighted average buy price across multiple lots. Essential for anyone who DCAs into individual stocks or averages down. Optionally enter the current market price for unrealized P&L.
XIRR Calculator — The annualized return on irregular cash flows. This is the right metric for SIP returns, real estate investments, and angel deals — anything where money goes in at non-uniform dates. Newton-Raphson with bisection fallback so it converges even on adversarial inputs. If you've been computing your SIP return as (current_value − total_invested) / total_invested, you've been overstating it; XIRR is the honest number.
Government scheme calculators
EPF Calculator — Projects your Employee Provident Fund corpus at retirement. Accounts for the 12% + 3.67% combined contribution and annual salary hikes. For most salaried Indians, EPF will be the largest single retirement asset.
NSC Calculator — National Savings Certificate maturity. 5-year fixed tenure, 7.7% p.a. compounded annually, qualifies for Section 80C.
Sukanya Samriddhi Yojana — The girl-child savings scheme. ₹1.5 lakh/year for 15 years at 8.2% tax-free maturity at age 21 builds ~₹64 lakh — comfortably covers higher education at top private universities. The best small-savings instrument for parents of daughters under 10.
APY Calculator — Atal Pension Yojana monthly contribution lookup. Uses the official PFRDA contribution table, not estimates. Pick your target monthly pension and entry age, get the exact amount you need to deposit monthly until 60.
Post Office MIS Calculator — Monthly income from a POMIS deposit. Best paired with SCSS for senior-citizen monthly income planning.
SCSS Calculator — Senior Citizens Savings Scheme. Highest fixed-rate scheme available (8.2%), max ₹30 lakh per individual. Quarterly payouts.
Banking calculators
RD Calculator — Recurring Deposit maturity with quarterly compounding (the standard convention used by Indian banks and post offices).
Car Loan EMI Calculator — EMI calculator pre-set with typical car loan parameters (5-year tenure, 9% rate). The math is the same as the generic EMI calculator, but the defaults guide you toward sensible values.
Home Loan EMI Calculator — EMI calculator pre-set for home loans (20-year tenure, 8.75% rate). Plus the home loan affordability rule: keep EMI under 40% of take-home pay (lower if you have other EMIs).
Tax & trading calculators
TDS Calculator — Tax Deducted at Source for nine different payment types. Includes the no-PAN flat 20% rule under Section 206AA. Essential for freelancers, landlords, and business owners managing TDS deductions.
Margin Calculator — Estimates margin required for stock trades across equity intraday, delivery, futures, and options. Reflects post-SEBI peak-margin rules (lower retail leverage than pre-2021).
Why the privacy guarantee matters here
Most Groww-style calculator sites are run by brokers or fintechs whose primary motivation is to capture leads. Their calculators are the top of a funnel that ends with "open a demat account with us" or "buy this insurance product." That's a fair business model — but it changes the incentives. The numbers you put in (salary, loan amount, portfolio size) become marketing-qualified leads.
Stax doesn't have that funnel. We don't have a brokerage, an insurance product, or a fintech app to pitch. The calculator is the product. The numbers you put in stay in your browser. You can run a sensitive calculation (your actual home loan amount, your real CTC, your portfolio's XIRR including private holdings) without worrying that it becomes a CRM record or shows up in a retargeting ad three days later.
This was the original reason Stax exists, and it applies as much to finance tools as to JSON formatters.
What's next on the finance side
A few things on the roadmap:
- Loan amortization schedule download — most Indian users want a year-wise principal-interest split they can save as PDF. Coming soon.
- Inflation-adjusted retirement calculator — the existing retirement calculator shows nominal numbers. An inflation-adjusted version helps people understand the real purchasing power they're saving toward.
- Tax regime optimizer — given your income and deductions, which regime (old vs new) saves more? The income tax calculator does this for static numbers; we'd like a slider that shows the breakeven across your full income range.
- Pro tier integration — once Pro launches (Q3 2026), saved scenarios will let you persist multiple "what-if" calculations for the same calculator.
If there's a specific Indian finance calculator you want and we don't have it, email us — we keep a list and prioritize by what people actually ask for.
— Built in 2026, in Mumbai.