These guides explain the calculations and file conversions behind the tools on this site, using real numbers rather than general advice: what an EMI actually costs over twenty years, how GST splits into CGST and SGST, why a CSV opened in Excel loses the leading zeros in a PIN code, what changes when subtitles move between SRT, VTT and ASS.
Every figure in a worked example is calculated, and every description of a tool's behaviour is checked against the tool itself, which is how several conversion bugs on this site were found and fixed. Each guide shows the date it was first published, and an updated date when it has been substantially revised. Guides are written by Chirag, who builds and maintains the tools.
business · · Updated
A line-by-line breakdown of an ₹8 lakh CTC showing where the money goes (employer PF, your own PF, professional tax, and TDS), plus the PF wage-ceiling detail that can change your in-hand pay by thousands a month.
Read more →business · · Updated
A worked ₹40 lakh example showing where your EMI goes, and what a shorter tenure, a lower rate, and prepayments each save in rupees.
Read more →business · · Updated
The fields a GST invoice must carry, how to write payment terms a client's accounts team can act on, and the MSME 45-day rule small suppliers in India should know about.
Read more →developer · · Updated
The technical basics that decide how a page appears in search and link previews: title, description and canonical tags, what robots.txt can and can't do, and the favicon sizes search engines actually use.
Read more →student · · Updated
Why averaging your semester SGPAs gives the wrong CGPA (8.00 instead of 7.76 in the worked example, or 76.0% instead of 73.7%), where the × 9.5 rule comes from, and how to work out the SGPA you need next semester.
Read more →developer · · Updated
Twelve common JSON mistakes, the exact error each one produces in Chrome, Firefox and Safari, why the reported position is sometimes after the real problem, and how to fix each.
Read more →developer · · Updated
Ten copy-ready CSS gradients (buttons, dark surfaces, progress bars, stripes, glows, gradient text, photo overlays), plus how gradient angles work and how to avoid the muddy grey middle.
Read more →student · · Updated
Word ranges by assignment type, the published limits for abstracts and application essays, how the ±10% leeway works in three university policies, what counts toward the limit, and measured words per page.
Read more →business · · Updated
₹1,00,000 at 7% under simple interest and yearly, quarterly and monthly compounding over 1 to 30 years, what an effective annual rate is, and why a 10% "flat" loan rate costs as much as 17.92% on a reducing balance.
Read more →business · · Updated
A ₹2,40,000 coffee machine run through payback period, ROI, annualized ROI and straight-line depreciation, why the annualized figure understates a machine that pays back monthly (25.9% vs 74.3%), and what depreciation does to reported profit.
Read more →business · · Updated
A ₹12 lakh income target turned into an hourly rate step by step, which input moves the rate most (billable hours, not overhead), why the naive 2,080-hour rate is half what you need, and how GST sits on top of the fee.
Read more →student · · Updated
One course worked through: the grade so far (81.8%) from the 60% already marked, the final-exam score needed for 80, 85 or 90 overall, and the category, points and dropped-score rules that change the answer.
Read more →developer · · Updated
The naming convention each language, database and URL expects, the PostgreSQL quirk that breaks camelCase columns, and what automatic case conversion does to acronyms like XMLHttpRequest and names like iPhone.
Read more →business · · Updated
The two GST formulas (adding tax and removing it), how the amount splits into CGST + SGST or IGST, and worked examples for discounts and invoices that mix tax rates.
Read more →developer · · Updated
How much a QR code can hold, why a shorter or uppercase link gives a code that scans more easily, what error correction actually protects against, and how to size one for print.
Read more →business · · Updated
The markup-to-margin conversion table, pricing a ₹600 product for a 40% margin (₹1,000, not ₹840), why margin calculated on a GST-inclusive price is wrong, and why a 20% discount means selling twice as many units.
Read more →developer · · Updated
Why UUIDs are used instead of auto-incrementing IDs, what the version number means, and when a UUID is (or isn't) the right choice.
Read more →converters · · Updated
Why double-clicking a CSV mangles PIN codes, long IDs and ₹ signs, what a careful CSV-to-Excel conversion does instead, and how XML records map to spreadsheet columns.
Read more →converters · · Updated
The same caption written in SRT, WebVTT and ASS, what each format can express, and exactly what survives when you convert between them: timing precision, italics, positioning and speaker tags.
Read more →converters · · Updated
A practical workflow for translating or reviewing subtitles in a spreadsheet: the column layout, how to make a second-language file, keeping timestamps intact, and when to pick .xlsx over CSV.
Read more →converters · · Updated
What Markdown turns into as HTML (and what it doesn't), what HTML loses when it becomes Markdown, and when stripping to plain text is the right move, with real before-and-after output.
Read more →converters · · Updated
How to check a page's title, description, canonical and social tags from its source, the JavaScript-rendering trap that makes View Source lie, and how to pull a table with merged cells into a spreadsheet.
Read more →converters · · Updated
How the five common image formats differ in compression, transparency and colour, with real file-size arithmetic, plus what changes when an image is converted in the browser.
Read more →converters · · Updated
Why resizing beats lowering quality, how to find the lowest quality setting that still looks right, when PNG compression can make a file bigger, and what happens to EXIF location data along the way.
Read more →converters · · Updated
The same invoice line rendered 14 ways (small text, blur, tilt, low contrast, a busy background, JPEG artifacts, Hindi, two columns) and run through this site's OCR, with the accuracy of each and the three fixes that took the average from 88.5% to 99.5%.
Read more →developer · · Updated
Every status code this site and the two APIs it uses returned in one afternoon of curl requests (301, 308, 304, 204, 400, 404 and 405), what each means, and the redirect that broke a CORS request.
Read more →developer · · Updated
#4F46E5 converted to RGB and HSL step by step, why 89.4% of all colours change when copied as whole-number HSL, why HSL lightness is not brightness (yellow and blue at 50% differ eightfold in contrast), and the alpha that hex can't write exactly.
Read more →developer · · Updated
A real token taken apart segment by segment: Base64URL and its missing padding, what exp and iat say in plain dates, why a 5-part token won't decode, and what a decoder can't tell you.
Read more →converters · · Updated
How dot-notation flattening turns nested objects and arrays into spreadsheet columns, what survives the trip back, and how JSON Lines differs from a normal JSON file.
Read more →developer · · Updated
A one-line report query, formatted step by step, and the AND/OR precedence bug the formatting exposes, plus why picking the right SQL dialect matters and a LEFT JOIN rule worth memorising.
Read more →converters · · Updated
What actually happens to your data when JSON becomes a spreadsheet, XML, or YAML: missing keys, nested values, leading zeros, and the XML array problem, with real converter output.
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