Guides

Evergreen reference pages that explain formats, concepts, and practical tools — each linked to a free calculator.

47 guides across Utilities, Finance, Health, and Developer topics

Finance — India

15 guides
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FinanceIndia

How GST Works in India: A Complete Guide

GST slabs, CGST vs SGST vs IGST, input tax credit, registration thresholds, and common invoicing mistakes.

8 min read
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FinanceIndia

How EMI Is Calculated: Formula and Examples

The reducing balance EMI formula explained with worked examples for home loans, car loans, and personal loans.

7 min read
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FinanceIndia

How SIP Returns Are Calculated

How mutual fund SIP returns work, what XIRR means, and how to compare lumpsum vs SIP investments.

8 min read
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FinanceIndia

What Is CIBIL Score and How Is It Calculated?

How CIBIL scores work, what factors affect your score, and how lenders use it for loan decisions.

6 min read
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FinanceIndia

How Income Tax Works in India (Old vs New Regime)

Tax slabs, deductions, the difference between old and new regimes, and how to calculate your liability.

9 min read
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FinanceIndia

What Is Gratuity and How Is It Calculated in India?

The Payment of Gratuity Act, eligibility rules, the gratuity formula, and tax treatment explained.

5 min read
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FinanceMath

How Compound Interest Works

The compound interest formula, the effect of compounding frequency, the Rule of 72, and real-world examples.

6 min read
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FinanceIndia

What Is the FIRE Number and How Do You Calculate It?

Financial Independence Retire Early — how to calculate your FIRE number in the Indian context with real inflation and return assumptions.

7 min read
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FinanceIndia

How PPF Works: Interest, Lock-In, Withdrawal Rules Explained

Complete guide to Public Provident Fund (PPF): interest rates, lock-in periods, withdrawal rules, tax benefits under 80C, and maturity calculations.

8 min read
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FinanceIndia

HRA Exemption Explained: How to Calculate & Claim It

Complete guide to House Rent Allowance (HRA) exemption: formula, metro vs non-metro cities, calculation method, and documentation required.

8 min read
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FinanceIndia

How TDS Works: Tax Deduction at Source Explained

TDS explained: who deducts, common TDS rates, Form 16, ITR filing with TDS, and how to claim TDS refunds.

7 min read
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FinanceIndia

NPS vs EPF: Which Is Better for Your Retirement?

Complete comparison of National Pension Scheme and Employee Provident Fund: contributions, tax benefits, returns, and when to choose each.

8 min read
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FinanceIndia

How to Read a Mutual Fund Factsheet

Understand mutual fund factsheets: NAV, expense ratio, holdings, performance metrics, and what each section means for your investment.

7 min read
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FinanceIndia

What Is Indexation and How Does It Reduce LTCG Tax?

Indexation benefit explained: indexed cost formula, LTCG tax reduction, when it applies, and real examples with calculations.

6 min read
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FinanceIndia

Section 80C Deductions: Complete Investment List & Tax Savings

All Section 80C eligible investments: PPF, EPF, ELSS, life insurance, home loan principal, and how to maximize tax savings up to Rs. 1.5 lakh.

7 min read
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Health

9 guides
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Health

What Is BMI and How Is It Calculated?

The BMI formula, Indian/Asian BMI categories, limitations of BMI, and how it differs for children vs adults.

5 min read
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HealthNutrition

How BMR and TDEE Work (Calorie Science Explained)

What Basal Metabolic Rate and Total Daily Energy Expenditure mean, how they are calculated, and how to use them.

6 min read
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HealthNutrition

How Macros Work: Protein, Carbs, and Fat Explained

What macronutrients are, how many calories each contains, and how to calculate your macro targets.

6 min read
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Health

What Is Body Fat Percentage and How Is It Measured?

Body fat measurement methods, healthy ranges for Indian men and women, and how it differs from BMI.

5 min read
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HealthFitness

How to Calculate Your Running Pace

The relationship between pace, speed, and distance. How to calculate splits and estimate race finish times.

4 min read
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HealthSleep

How Sleep Debt Works and How to Calculate It

Sleep debt explained: calculation formula, cumulative health effects, recovery timeline, and science-backed strategies to manage chronic sleep deprivation.

8 min read
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HealthFitness

What Is VO2 Max and How Is It Measured?

VO2 max explained: measurement methods, age-based reference values, health benefits, training protocols, and factors affecting your fitness.

8 min read
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HealthPregnancy

How to Calculate Pregnancy Due Date (EDD)

Estimated Delivery Date calculation: Naegele's rule, LMP method, ultrasound dating, gestational age, and pregnancy timeline overview.

7 min read
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HealthCardio

Understanding Blood Pressure Readings: Systolic and Diastolic

Blood pressure guide: normal ranges by age, hypertension stages, management strategies, and when to consult a doctor.

7 min read
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SaaS & Developer

12 guides
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DeveloperSecurity

How JWT Authentication Works

JWT structure, signing algorithms, the full auth flow, refresh token patterns, and the four vulnerabilities every developer must know.

8 min read
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DeveloperEncoding

What Is Base64 Encoding?

How Base64 encoding works, where it is used, and the difference between encoding and encryption.

5 min read
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DeveloperAPI

API Rate Limiting Explained

Fixed window, sliding window, token bucket — how rate limiting algorithms work and how to read rate limit response headers.

7 min read
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DeveloperDevOps

What Is a CRON Expression?

How cron expressions work, the five-field syntax, special strings like @daily, and real scheduling examples.

6 min read
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SaaSMetrics

How MRR and ARR Are Calculated

Monthly and Annual Recurring Revenue — exact definitions, what to include and exclude, the five MRR movements, and what investors look for.

6 min read
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SaaSMetrics

What Is Churn Rate and Why It Matters for SaaS

Customer churn and revenue churn — how to calculate them, what good looks like, and how churn connects to LTV.

6 min read
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SaaSMetrics

What Is the CAC:LTV Ratio and Why VCs Care About It

How to calculate Customer Acquisition Cost and Lifetime Value, what a healthy ratio looks like, and how investors use it.

7 min read
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DeveloperSecurity

How OAuth 2.0 Works: PKCE Flow for SPAs

OAuth 2.0 explained: authorization code flow, PKCE for single-page applications, access tokens, refresh tokens, and secure implementation.

8 min read
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DeveloperAPI

What Is a Webhook Payload and How to Validate It

Webhook explained: payload structure, validation, security, signature verification, and best practices for implementing webhooks.

7 min read
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DeveloperReference

HTTP Status Codes Reference Guide

Complete reference of HTTP status codes: 2xx success, 3xx redirects, 4xx client errors, 5xx server errors with examples.

8 min read
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DeveloperSecurity

What Is CORS and How to Fix It

CORS (Cross-Origin Resource Sharing) explained: same-origin policy, preflight requests, headers, and how to fix cross-origin errors.

8 min read
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DeveloperDatabase

SQL vs NoSQL: When to Use Each Database

SQL vs NoSQL comparison: relational vs document, ACID vs BASE, scalability, consistency, and when to choose each.

9 min read
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Practical Guides for Every Calculation

Our Guides section answers the why behind every calculator — from understanding how GST is structured before you compute it, to knowing what XIRR means before you trust your SIP return figure.

Finance & Tax Guides for India

Our India-focused finance guides cover GST, EMI, SIP, PPF, HRA, TDS, tax deductions, NPS vs EPF, income tax regimes, CIBIL scores, gratuity, and FIRE planning with real INR examples and India-specific context that generic global guides miss.

Developer & Technical Reference

Understand Unix timestamps, JWT authentication, Base64 encoding, cron expressions, API rate limiting, OAuth 2.0, webhooks, HTTP status codes, CORS, and database design with clear explanations, code examples in JavaScript and Python, and links to the tools that do the work for you.

Health, Fitness & Medical Guides

From BMI and body fat percentage to sleep debt, VO2 max, blood pressure, and pregnancy due dates — every guide gives you the formula, the edge cases, and the practical context so you can interpret calculator results with confidence.

Home & Interior Design Planning

Plan your home projects with confidence: flooring cost estimation, paint quantity calculations, Vastu principles, and home renovation budgeting — with India-specific rates, cost breakdowns, and step-by-step guidance.

How These Guides Work

  • Every guide links directly to the relevant free calculator tool.
  • Real examples with actual numbers — no abstract theory.
  • India-specific context for finance and health topics.
  • Updated to reflect current tax regimes, GST slabs, and regulations.