9 min read
How to Test a Keyboard Properly
A key that seems dead is usually not a broken switch. Test in the right order — registration, rollover, chatter, latency, feel — and you find the real fault.
10 tools referenced
Guides
Practical guides on using online tools well — written to answer the question, not to fill a page.
Explanations that sit above the tools. Each one answers a question properly and then points at the handful of tools worth using for it — written to be useful on its own, not to introduce a product.
10 min read
How to Check a New Monitor Before the Return Window Closes
Dead pixels, backlight bleed and IPS glow are three different things with three different verdicts. Here is what to check, and what counts as a defect.
15 tools referenced
8 min read
Why One Cup of Flour Is Not One Cup of Sugar
A cup is a volume and a gram is a mass, so there is no single cups-to-grams number. Here is why flour is the worst offender and how to measure it properly.
10 tools referenced
8 min read
Margin vs Markup, and Why the Difference Costs Money
A 50% markup is a 33% margin. Getting the two confused underprices products by a third, and the error compounds through every tier below you.
11 tools referenced
7 min read
Editing PDFs Without Uploading Them Anywhere
Most online PDF tools upload your file to a server. Browser-side tools do the same work locally. Here is the difference, and how to verify it yourself.
7 tools referenced
8 min read
Where Your Water Bill Actually Goes
Showers are about half of household water, and a silent running toilet can beat everything else combined. The breakdown, and what actually pays back.
6 tools referenced
8 min read
Why Your Blood Test Is in mg/dL Here and mmol/L There
The same blood sample reads 100 in one country and 5.6 in another. Both are right. Here is the factor for each analyte and why one shared number cannot work.
9 tools referenced
7 min read
Marla, Kanal and Bigha: What They Actually Measure
One Marla is 272.25 square feet and one Kanal is exactly twenty of them. Bigha is not one unit at all. The exact factors, and where they stop being exact.
8 tools referenced
9 min read
Candle Making by Weight: Wax, Fragrance and Burn Time
Wax is sold by weight and jars measured by volume. Get that bridge wrong, or add fragrance the wrong way round, and the jar overflows. The arithmetic, properly.
6 tools referenced
12 min read
What 1:2:4 Actually Means
A mix ratio counts buckets, not kilograms, and 1 m³ of concrete needs 1.54 m³ of dry material. The exact quantities for 1:2:4, M20 and the rest.
10 tools referenced
11 min read
What Password Strength Actually Measures
Strength is a number, and the number is bits. Sixteen lowercase letters beat eight of every symbol on the keyboard by six million times the work.
8 tools referenced
12 min read
What a Gold Rate Actually Buys
A rate is meaningless without a purity and a unit. 22K at a 24K rate overpays by 9.09%, and one tola is 11.6638038 g exactly.
13 tools referenced
11 min read
Why a 10% Loan Costs 17%
A 10% flat loan over five years is a 17.27% reducing-balance loan. Same headline number, 82% more interest. The arithmetic, and how to compare offers.
8 tools referenced
12 min read
Pixels, DPI and Why Your Image Is Too Big
Pixels are the only dimension an image really has. DPI is a printing instruction, aspect ratio decides what is cropped, and file size is separate again.
12 tools referenced
11 min read
Why the Hijri Date Moves Every Year
A lunar year is 354.367 days against 365.2425, so a Hijri date arrives about 10.9 days earlier each year and comes full circle in 33.6.
8 tools referenced
11 min read
Why a Key Does Not Register
A key press passes through seven layers before a page sees it, and only three of them travel with the keyboard. Check them in order to find the real fault.
7 tools referenced
10 min read
Keyboard Repeat Versus Chatter
A held key repeating, a worn switch bouncing and a fast double tap all look like a key firing twice. How each one shows up, and how to tell them apart.
4 tools referenced
10 min read
Why Mouse Polling Results Differ by Browser
The same 1000 Hz mouse can read 60, 144 or 1000 in different tests. Display frames, merged samples and rounded clocks explain every one of those numbers.
4 tools referenced
9 min read
Why Two Texts That Look the Same Don't Match
Zero-width spaces, non-breaking spaces, curly quotes, lookalike letters and accents stored two ways make identical text fail to match. How to find each.
8 tools referenced
8 min read
Why Typing Tests Give Different WPM Scores
The same typing run can score 50, 48 or 40 WPM depending on the test. How gross and net speed, accuracy, the material and the test length change the number.
6 tools referenced
8 min read
Why a 1 TB Drive Shows 931 GB
Storage is sold in powers of 1,000 and often shown in powers of 1,024; internet speed is sold in bits and shown in bytes. The arithmetic behind both gaps.
7 tools referenced
8 min read
Why a 34-Inch Ultrawide Is Not Bigger Than a 32-Inch Monitor
A screen's diagonal hides its shape. Width, height, area and pixel density for 24" to 49" monitors, and why a 34" ultrawide has less area than a 32".
7 tools referenced
8 min read
Why a USB Keyboard Stops at Six Keys
A USB keyboard's basic report has room for six keys plus modifiers, so a seventh key vanishes. How 6KRO and NKRO work, and how to test yours.
5 tools referenced
8 min read
How Many Dead Pixels Are Acceptable on a Monitor
Under ISO pixel class II a 4K monitor can have about 16 bright pixels and still pass. What the standard allows at each resolution and what brands promise.
6 tools referenced
8 min read
Will Your Webcam and Mic Pass an Online Proctored Exam?
Pearson VUE OnVUE needs a 640×480 webcam at 10 fps, 6 Mbps down and 2 Mbps up, no headsets and one screen. How to check each requirement yourself.
5 tools referenced
9 min read
Why Your 144 Hz Monitor Is Stuck at 60 Hz
A 1440p 144 Hz signal needs about 13.4 Gbit/s; HDMI 1.4 carries 8.16. Cable, port, Windows setting or dock: how to find which one caps you at 60 Hz.
5 tools referenced
7 min read
Why Your Webcam Drops to 15 fps in Low Light
A frame can only be exposed for as long as it lasts: 33 ms at 30 fps, 67 ms at 15. In dim light webcams slow down to gather light. How to get 30 fps back.
5 tools referenced
9 min read
How Long Do You Have to Return a Faulty Product? UK, EU and US
UK: 30 days to reject faulty goods, 14 to cancel online orders. EU: a 2-year legal guarantee. US: no general legal right to return. The rules compared.
8 tools referenced
7 min read
The UK Energy Price Cap, Explained With the Numbers
October to December 2026: electricity 26.32p per kWh plus 54.83p a day, with no VAT. How the cap works and how to turn it into your own bill.
7 tools referenced
Every tool page also carries its own explanation: what it does, the formula or method behind it, a worked example, and an honest note about where it stops being reliable. Browse all 2,284 tools.