Ecommerce sellers
Amazon, Flipkart, eBay, Etsy — calculate real margins after fees, ad spend, and returns. Know exactly what a listing makes before you stock it.
View toolsAbout Calcrux
Free business calculators built for real decisions
Calcrux is a free calculator and simulator platform for people who actually run businesses — sellers, manufacturers, founders, and finance professionals worldwide.
- 100+
- Free tools
- 5
- Ecosystems
- 9
- Countries
- Free
- Always
Our mission
Too many business decisions are made on gut feeling because the right tool is behind a paywall, buried in a spreadsheet, or simply doesn't exist. We've already built 100+ precision tools — calculators, simulators, estimators — and are scaling to 500+, each backed by real domain logic: actual fee schedules, ISO manufacturing standards, and verified financial formulas. Anyone on the planet can use them, free, forever.
Who uses Calcrux
Built for every business operator
From a solo seller checking margins to an operations team modelling quarterly targets — there's a tool for you.
Manufacturers
Track OEE, MTBF, production costs, and inventory turnover with tools built on ISO standards — not spreadsheet guesswork.
View toolsStartup founders
Model burn rate, runway, equity splits, and SaaS metrics. Make funding and hiring decisions with numbers you can trust.
View toolsFinance professionals
Plan SIP returns, compound growth, and portfolio scenarios with globally accurate calculators adapted to your local tax and currency rules.
View toolsHR & operations teams
Compute in-hand salaries, payroll costs, and compliance figures — built for real payroll systems, not simplified estimates.
View toolsWhat we stand for
Three principles, no compromises
Instant accuracy
Every tool calculates in real-time. No submit buttons, no waiting — just answers as you type.
Global first
Auto-detects your country. Adapts currencies, tax labels, and number formats for 9 countries and counting.
Privacy by design
All calculations happen in your browser. Your numbers never touch our servers.
How we build
Engineering principles
01
Real business logic
Engines model how Amazon FBA fees, OEE, runway, or SIP returns actually work — not a generic formula.
02
Tested calculations
Every tool ships with unit tests covering edge cases. We treat correctness as a feature, not a nice-to-have.
03
Free forever
No premium tier, no credits, no signup. Free tools should stay free — period.
04
Open by default
Formulas are explained in every FAQ. No black boxes — you can verify every result yourself.
Where we're going
500+ tools across 5 ecosystems
We're scaling to 500+ tools across five ecosystems: Ecommerce, India Business, Manufacturing, Startup & BI, and Operational Financial Planning. Each tool is built with real business logic, tested against actual use cases, kept current with fee changes, and free — no premium tier, no credits, no account required, ever.
Common Questions
Frequently asked questions
What Calcrux is, who built it, how it stays free, and the regions it supports.
01What is Calcrux?
Calcrux is a free online calculator platform with 100+ tools across ecommerce, India business and tax, manufacturing, startup, and finance. Every tool is built on real business logic and runs entirely in your browser — no sign-up required.
02Is Calcrux really free?
Yes, completely. Every calculator on Calcrux is free with no premium tier, no credits, and no account required. We believe decision-making tools should be accessible to everyone, not gated behind a paywall.
03Who is Calcrux for?
Calcrux is built for ecommerce sellers, manufacturers, startup founders, finance professionals, and HR teams — anyone who makes business decisions that benefit from accurate, fast calculations.
04How accurate are the calculators?
Every engine is written in pure TypeScript and unit-tested against real-world scenarios. Formulas are sourced from industry standards and official fee schedules, then documented openly in each tool's FAQ.
05Does Calcrux store my data or require an account?
No. All calculations run locally in your browser. Your inputs never leave your device and are not sent to any server. No account, no tracking cookies, no data collection.
06What ecosystems does Calcrux cover?
Calcrux currently covers five ecosystems: Ecommerce Seller Operations, India Business, Manufacturing & ERP, Startup & Business Intelligence, and Operational Financial Planning, with 500+ tools planned across all five.
07Who created Calcrux?
Calcrux is built and maintained by Sajid Hussain, its editor and reviewer. He verifies every formula against authoritative sources, reviews each tool, and keeps fee schedules and tax limits current as platforms revise them.
08How does Calcrux make money?
Calcrux is free and currently runs with no ads or paid tiers. We plan to add unobtrusive ads and relevant affiliate links in future, but the calculators themselves will always stay free, with no sign-up or paywall.
09How often are the calculators updated?
Whenever the underlying rules change. Fee schedules, tax slabs, and statutory limits are tracked centrally and updated as platforms and budgets revise them — each tool shows its last-reviewed date so you can see how current it is.
10Which countries and currencies does Calcrux support?
Calcrux auto-detects your country and adapts currency, tax labels, and number formats for nine regions: the US, India, UK, Australia, Canada, UAE, Singapore, Germany, and France. You can also switch region manually.
The team
Built and reviewed by real people
SH
Sajid Hussain
Editor & Reviewer
Verifies formulas, reviews tool content, and keeps fee schedules current with platform changes.
Found a bug, spotted a wrong formula, or have a tool request? We read every message and respond to substantive ones.
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