Blog
Guides & explainers.
A calculator gives you the number. These explain it — what each line in your salary structure is for, which tax regime actually leaves you with more, what a monthly investment compounds into, and what a metro journey across Delhi costs. Every figure below is computed at build time by the same modules the calculators run, so the articles and the tools can never disagree.
Science
How a vernier scale actually works
A vernier caliper reads to a fiftieth of a millimetre with no lens, no screw and no electronics. It does it by engraving fifty divisions across forty-nine millimetres, so that exactly one line can ever be flush — turning a fraction you would have to estimate into a number you can simply count.
8 min read
Science
Turbocharging: what boost actually does to an engine
A turbocharger runs a compressor off energy that was already leaving through the exhaust pipe. That is the whole trick, and everything people argue about — lag, boost pressure, wastegates, intercoolers, heat — follows from making it work without destroying the engine.
9 min read
Science
Why a diesel has no spark plug
A petrol engine compresses a mixture and then lights it. A diesel compresses air until the air itself is hot enough to light the fuel the moment it arrives. Everything else that separates the two — the compression ratio, the injection timing, the glow plugs, the noise — comes out of that one decision.
8 min read
Finance
Your EMI is mostly interest at first
The instalment never changes, but what it is made of changes every month. On a ₹30 lakh home loan at 8.5% over 20 years, the first year puts about ₹60,000 against the loan and ₹2.5 lakh against interest — and it takes until year 12 before that flips.
8 min read
Transit
What a Delhi Metro journey actually costs
The distance slabs DMRC revised in August 2025, the smart-card and off-peak discounts that come off them, and the thing that catches people out: four different operators run trains on this map, and three of them sell you a separate ticket.
8 min read
Science
Two-stroke vs four-stroke: what the extra 360° buys you
A two-stroke engine fires on every crankshaft revolution; a four-stroke fires on every second one and spends the extra 360° breathing. That single difference decides power-to-weight, fuel consumption, emissions and how long the engine lasts — and it is why one of them disappeared from cars and the other never did.
7 min read
Finance
CTC vs in-hand salary: where the rest of your package goes
Your offer letter says ₹12 LPA. Your bank account disagrees. Here is every component that sits between the two — employer PF, gratuity, employee PF, professional tax and income tax — with the monthly take-home worked out for CTCs from ₹6 lakh to ₹40 lakh.
8 min read
Finance
Old vs new tax regime: which one leaves you with more?
Both slab tables side by side, the §87A rebate and its marginal relief explained, and the one number that actually decides it — how much in deductions you need before the old regime wins at your income.
9 min read
Finance
SIP vs lump sum: what ₹10,000 a month actually becomes
The SIP formula in plain English, a table of what ₹5,000 / ₹10,000 / ₹25,000 a month grows to at 10%, 12% and 15% over 5 to 20 years, and an honest answer to whether investing it all at once would have done better.
7 min read
Looking for the tools themselves? Every guide links to its calculator, or start from the full calculator list — or the Learn tracks if you came for Git, npm or Claude Code.