Percentage Calculator
Choose the right percentage formula for a percentage of a number, discount, increase or decrease, and compare worked examples.
Read the percentage guide →Tool Guides & Examples
Use these practical guides to understand the calculation, choose the right inputs, follow a worked example and spot common mistakes. Each tool on the homepage also includes an in-tool explanation, usage steps and an example where applicable. For important financial, tax, health or engineering decisions, verify results with current authoritative information.
GST Calculator
Learn how to add GST, extract tax from a tax-inclusive total and understand an illustrative CGST/SGST split.
Read the GST guide →EMI Calculator
Understand the fixed-rate EMI formula, monthly interest rate, total interest and limits of a loan estimate.
Read the EMI guide →Word Counter
Understand word and character counts, whitespace, punctuation, Unicode and platform-specific text limits.
Read the word counter guide →QR Code Generator
Choose QR content, download and test the result, and learn privacy and scanning precautions.
Read the QR code guide →Unit Converter
Choose matching units, use conversion factors correctly and avoid rounding errors in technical calculations.
Read the unit converter guide →How to Check a Calculator Result
Learn to verify formulas, units, rounding and assumptions before relying on a calculator output.
Read calculation methods →Guides for every tool
Browse the complete tool-by-tool directory, with a dedicated section, instructions and an example for every tool currently listed on the website.
Need instructions for another tool?
Open the tool from the homepage and scroll within its panel to the About this tool section. It provides a description, steps and a sample example; engineering calculators also show their stated formula and assumptions where available. Use a small sample first and check whether the tool's limitations fit your task.
How we approach accuracy
Tool results depend on the inputs, units, formulas, rounding and any third-party data source. We aim to make assumptions visible and welcome corrections through the contact page. This site does not claim that every estimate replaces professional advice, official tax rules, engineering codes or a destination platform's own counting rules.
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Engineering calculator formulas
Browse formulas, worked examples, input guidance and limitations for 172 branch-wise engineering calculators.