# Online Calculators

> Fast, accurate, and free online calculators for finance, health, math, business, and unit conversion. EMI, SIP, BMI, GST, percentage, and 1000+ more calculators. Free, instant, no signup. Built as a static Jekyll site on GitHub Pages at https://online-calculators.com.

This file helps AI agents and developers understand Online Calculators: what we offer, where to link users, and which pages contain authoritative calculator logic. All tools run client-side in the browser; results are estimates, not professional advice.

- **Primary audience:** people searching for free EMI, BMI, GST, pregnancy due date, mortgage, and unit conversion tools.
- **URL pattern:** `/{category}/{calculator-slug}/` (e.g. `/health/pregnancy-calculator/`).
- **Full catalog:** https://online-calculators.com/llms-full.txt — complete list with formulas, types, and metadata.
- **Sitemap:** https://online-calculators.com/sitemap.xml
- **Repository:** https://github.com/nitinkanish/nitinkanish.github.io
- **Last generated:** 2026-06-25

## Featured Calculators

- [Percentage Calculator](https://online-calculators.com/math/percentage-calculator/): Free percentage calculator for X% of Y, percent change, increase, decrease, and reverse percentage — with formula shown instantly. Formula: Percentage = (Part / Whole) × 100.
- [GST Calculator](https://online-calculators.com/business/gst-calculator/): Calculate GST inclusive and exclusive amounts for Indian tax rates of 5%, 12%, 18%, and 28%. Formula: GST Amount = Price × Rate / 100; Inclusive Price = Price × (1 + Rate/100).
- [BMI Calculator](https://online-calculators.com/health/bmi-calculator/): Calculate Body Mass Index and get personalized health category recommendations. Formula: BMI = weight (kg) / height (m)².
- [EMI Calculator](https://online-calculators.com/finance/emi-calculator/): Calculate monthly EMI for home, car, and personal loans with amortization breakdown. Formula: EMI = P × r × (1+r)^n / ((1+r)^n - 1).
- [SIP Calculator](https://online-calculators.com/finance/sip-calculator/): Estimate mutual fund SIP returns with step-up options and wealth projection charts. Formula: FV = P × ((1+r)^n - 1) / r × (1+r).
- [Pregnancy Due Date Calculator](https://online-calculators.com/health/pregnancy-calculator/): Calculate your due date, pregnancy week, trimester, and days until delivery from LMP or conception date. Formula: Due Date = LMP + 280 days (Naegele's Rule).
- [Compound Interest Calculator](https://online-calculators.com/finance/compound-interest-calculator/): Calculate compound interest with regular contributions and visualize wealth growth over time. Formula: A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)].
- [Scientific Calculator](https://online-calculators.com/scientific/scientific-calculator/): Full-featured scientific calculator with trigonometry, logarithms, and advanced functions. Formula: Varies by operation.

## Business Calculators

_Calculate profit margins, GST, markup, and business metrics to optimize pricing and tax compliance for your enterprise._

- [Profit Margin Calculator](https://online-calculators.com/business/profit-margin-calculator/): Calculate gross, operating, and net profit margins for your business pricing strategy. Formula: Profit Margin = (Revenue - Cost) / Revenue × 100.
- [GST Calculator](https://online-calculators.com/business/gst-calculator/): Calculate GST inclusive and exclusive amounts for Indian tax rates of 5%, 12%, 18%, and 28%. Formula: GST Amount = Price × Rate / 100; Inclusive Price = Price × (1 + Rate/100).
- [Markup Calculator](https://online-calculators.com/business/markup-calculator/): Calculate selling price, profit, and margin from cost price and markup percentage. Formula: Selling Price = Cost × (1 + Markup%/100).
- [Business Calculators (category hub)](https://online-calculators.com/business/): Browse all business tools.

## Construction Calculators

_Estimate materials, areas, volumes, and costs for construction and renovation projects._

- [Area Calculator](https://online-calculators.com/construction/area-calculator/): Calculate area of rectangle, circle, triangle, and room layouts for construction and renovation. Formula: Rectangle: l×w | Circle: πr² | Triangle: ½bh.
- [Volume Calculator](https://online-calculators.com/construction/volume-calculator/): Calculate volume of rectangular prisms, cylinders, and spheres for concrete, fill, and tank capacity. Formula: Box: l×w×h | Cylinder: πr²h | Sphere: ⁴⁄₃πr³.
- [Construction Calculators (category hub)](https://online-calculators.com/construction/): Browse all construction tools.

## Unit Converters

_Convert length, weight, temperature, and more between metric and imperial units instantly with precision._

- [Length Converter](https://online-calculators.com/converters/length-converter/): Convert between meters, feet, inches, miles, kilometers, and more length units. Formula: Target = Source × Conversion Factor.
- [Weight Converter](https://online-calculators.com/converters/weight-converter/): Convert between kilograms, pounds, ounces, grams, stones, and more weight units. Formula: Target = Source × Conversion Factor.
- [Temperature Converter](https://online-calculators.com/converters/temperature-converter/): Convert between Celsius, Fahrenheit, and Kelvin temperature scales instantly. Formula: °F = (°C × 9/5) + 32; K = °C + 273.15.
- [Speed Converter](https://online-calculators.com/converters/speed-converter/): Convert speed between km/h, mph, m/s, knots, and feet per second instantly. Formula: Target = Source × conversion factor.
- [Unit Converters (category hub)](https://online-calculators.com/converters/): Browse all converters tools.

## Date & Time Calculators

_Calculate age, date differences, and time intervals with precision._

- [Age Calculator](https://online-calculators.com/date-time/age-calculator/): Calculate exact age in years, months, days, hours, and minutes from date of birth. Formula: Age = Current Date - Date of Birth.
- [Date Difference Calculator](https://online-calculators.com/date-time/date-difference-calculator/): Calculate exact days, weeks, months, and years between any two dates instantly. Formula: Difference = End Date − Start Date.
- [Date & Time Calculators (category hub)](https://online-calculators.com/date-time/): Browse all date-time tools.

## Education Calculators

_GPA, grade, and academic calculators for students and educators._

- [GPA Calculator](https://online-calculators.com/education/gpa-calculator/): Calculate weighted GPA on a 4.0 scale from course grades and credit hours. Formula: GPA = Σ(Grade Points × Credits) / Σ(Credits).
- [Grade Calculator](https://online-calculators.com/education/grade-calculator/): Calculate weighted course grade from assignments, exams, and project scores with custom weights. Formula: Grade = Σ(Score × Weight) / Σ(Weight).
- [Education Calculators (category hub)](https://online-calculators.com/education/): Browse all education tools.

## Finance Calculators

_Plan your financial future with EMI, SIP, FD, compound interest, and loan calculators. Make informed investment and borrowing decisions with accurate projections._

- [EMI Calculator](https://online-calculators.com/finance/emi-calculator/): Calculate monthly EMI for home, car, and personal loans with amortization breakdown. Formula: EMI = P × r × (1+r)^n / ((1+r)^n - 1).
- [SIP Calculator](https://online-calculators.com/finance/sip-calculator/): Estimate mutual fund SIP returns with step-up options and wealth projection charts. Formula: FV = P × ((1+r)^n - 1) / r × (1+r).
- [FD Calculator](https://online-calculators.com/finance/fd-calculator/): Calculate fixed deposit maturity amount with quarterly, monthly, and annual compounding. Formula: A = P × (1 + r/n)^(n×t).
- [Compound Interest Calculator](https://online-calculators.com/finance/compound-interest-calculator/): Calculate compound interest with regular contributions and visualize wealth growth over time. Formula: A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)].
- [Loan Payoff Calculator](https://online-calculators.com/finance/loan-payoff-calculator/): Calculate how extra EMI payments reduce loan tenure and total interest on home, car, and personal loans. Formula: Interest saved = Original total interest − New total with extra payments.
- [Finance Calculators (category hub)](https://online-calculators.com/finance/): Browse all finance tools.

## Fitness Calculators

_Track macros, heart rate zones, and workout metrics for optimal fitness performance._

- [Macro Calculator](https://online-calculators.com/fitness/macro-calculator/): Calculate daily protein, carbs, and fat targets based on your calories and fitness goals. Formula: Protein g × 4 + Carbs g × 4 + Fat g × 9 = Calories.
- [Heart Rate Zone Calculator](https://online-calculators.com/fitness/heart-rate-zone-calculator/): Calculate max heart rate and training zones for fat burn, cardio, and peak performance. Formula: Max HR ≈ 220 − Age | Zones = % of max HR.
- [Fitness Calculators (category hub)](https://online-calculators.com/fitness/): Browse all fitness tools.

## Health Calculators

_Track your wellness with BMI, BMR, calorie, pregnancy, and fitness calculators. Understand your body metrics and set achievable health goals._

- [BMI Calculator](https://online-calculators.com/health/bmi-calculator/): Calculate Body Mass Index and get personalized health category recommendations. Formula: BMI = weight (kg) / height (m)².
- [BMR Calculator](https://online-calculators.com/health/bmr-calculator/): Calculate Basal Metabolic Rate to understand daily calorie needs at rest. Formula: BMR (M) = 10W + 6.25H - 5A + 5; BMR (F) = 10W + 6.25H - 5A - 161.
- [Calorie Calculator](https://online-calculators.com/health/calorie-calculator/): Calculate daily calorie needs for weight loss, maintenance, or muscle gain goals. Formula: TDEE = BMR × Activity Factor.
- [Pregnancy Due Date Calculator](https://online-calculators.com/health/pregnancy-calculator/): Calculate your due date, pregnancy week, trimester, and days until delivery from LMP or conception date. Formula: Due Date = LMP + 280 days (Naegele's Rule).
- [Health Calculators (category hub)](https://online-calculators.com/health/): Browse all health tools.

## Math & Percentage Calculators

_Solve everyday math problems with fraction, ratio, percentage, exponent, square root, and rounding calculators. Quick, accurate results for students and professionals._

- [Percentage Calculator](https://online-calculators.com/math/percentage-calculator/): Free percentage calculator for X% of Y, percent change, increase, decrease, and reverse percentage — with formula shown instantly. Formula: Percentage = (Part / Whole) × 100.
- [Fraction Calculator](https://online-calculators.com/math/fraction-calculator/): Free fraction calculator to add, subtract, multiply, and divide fractions — auto-simplifies to lowest terms with decimal result. Formula: a/b ± c/d with common denominator; result simplified via GCD.
- [Ratio Calculator](https://online-calculators.com/math/ratio-calculator/): Free ratio calculator to simplify ratios and solve proportions — find missing values with cross-multiplication instantly. Formula: a:b simplified by GCD; scale via cross-multiplication.
- [Square Root Calculator](https://online-calculators.com/math/square-root-calculator/): Free square root calculator — find √n for any number, detect perfect squares, and see exact or decimal results. Formula: √n = n^0.5.
- [Exponent Calculator](https://online-calculators.com/math/exponent-calculator/): Free exponent calculator — compute base raised to any power including negative and decimal exponents instantly. Formula: result = base^exponent.
- [Rounding Calculator](https://online-calculators.com/math/rounding-calculator/): Free rounding calculator — round, floor, ceil, or truncate any number to 0–10 decimal places instantly. Formula: Round(n, d) = round n to d decimal places.
- [Math & Percentage Calculators (category hub)](https://online-calculators.com/math/): Browse all math tools.

## Mortgage Calculators

_Calculate monthly mortgage payments, affordability, and amortization schedules for home loans and property financing._

- [Mortgage Calculator](https://online-calculators.com/mortgage/mortgage-calculator/): Calculate monthly mortgage payments, total interest, and amortization for US home loans. Formula: M = P × r × (1+r)^n / ((1+r)^n - 1).
- [Mortgage Affordability Calculator](https://online-calculators.com/mortgage/mortgage-affordability-calculator/): Calculate how much house you can afford based on income, debts, down payment, and mortgage rate. Formula: Max payment ≈ 28% of gross monthly income (housing ratio).
- [Mortgage Calculators (category hub)](https://online-calculators.com/mortgage/): Browse all mortgage tools.

## Scientific Calculators

_Advanced scientific and engineering calculators for complex mathematical operations._

- [Scientific Calculator](https://online-calculators.com/scientific/scientific-calculator/): Full-featured scientific calculator with trigonometry, logarithms, and advanced functions. Formula: Varies by operation.
- [Scientific Calculators (category hub)](https://online-calculators.com/scientific/): Browse all scientific tools.

## Statistics Calculators

_Mean, median, standard deviation, and statistical analysis tools for data professionals._

- [Standard Deviation Calculator](https://online-calculators.com/statistics/standard-deviation-calculator/): Calculate mean, variance, and standard deviation for any dataset — sample or population. Formula: σ = √(Σ(x−μ)² / N).
- [Mean Median Mode Calculator](https://online-calculators.com/statistics/mean-median-mode-calculator/): Calculate mean, median, mode, range, and count for any dataset instantly. Formula: Mean = Σx/n | Median = middle value | Mode = most frequent.
- [Statistics Calculators (category hub)](https://online-calculators.com/statistics/): Browse all statistics tools.

## Site Pages

- [Home](https://online-calculators.com/): Search and browse all calculators.
- [All Categories](https://online-calculators.com/categories/): Category directory.

- [About](https://online-calculators.com/about/): Mission and team.

## Optional

Secondary pages — safe to skip when context is limited.

- [Privacy Policy](https://online-calculators.com/privacy-policy/): Data collection, cookies, and GA4 (consent-based).
- [Terms of Service](https://online-calculators.com/terms-of-service/): Usage terms and disclaimers.
- [Cookie Policy](https://online-calculators.com/cookie-policy/): Cookie categories and consent.
- [Sitemap](https://online-calculators.com/sitemap.xml): XML sitemap for crawlers.
- [Complete LLM catalog](https://online-calculators.com/llms-full.txt): Full machine-readable site index with formulas and calculator types.