Toolfiddle Blog
Guides for the tools you actually use
Every post here sits next to a tool we built. If the tool answers the question in a second, the post explains the thing behind it: the rule, the trade-off, and where people get caught out.
How to Read a Powerlifting Results Sheet (and Work Out Who Really Won)
A results PDF looks like noise until you know what each column does. Here is a line-by-line walkthrough of a sample sheet, plus how placings, tiebreaks and Best Lifter are actually decided.
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Latest posts
One guide per tool so far. More from each cluster is on the way.
Reading Your Aquarium Test Kit: What Every Number Means
The same 1 ppm ammonia reading is a mild problem in one tank and an emergency in another, and pH is the reason. Here is what every number on your test kit means and what to do about it.
The DOT 30-Minute Break Rule: When It's Due and What Actually Counts
The trigger changed in 2020 and most older guides never caught up. What actually starts the 8-hour count, why a 20-minute fuel stop is worth nothing, and how to place the break so it costs you no miles.
Sourdough Discard: What to Do With It, and When to Bin It
Hooch is fine. Acetone smell is fine. Pink, orange or fuzzy is not. Here is what discard actually is, how long it keeps, what it does in a batter, and how to stop generating so much of it.
Tongue Weight: How to Measure It, Why 10 to 15 Percent, and What Sway Really Is
Tongue weight is the number that quietly eats your truck's payload and decides whether your trailer tracks straight at 65 mph. Here is how to measure it three different ways and how to change it on purpose.
Glasses, Hats and Clothing: Passport Photo Rules People Get Wrong
Glasses are the rule that changed and the one people still get wrong. Here is where the US, the UK and Schengen actually differ on eyewear, head coverings, hair, makeup, jewellery and what you wear on your shoulders.
Grandchildren and the Orphaned Grandchild in Islamic Inheritance
A living son blocks his father's grandchildren, which is why the orphaned grandchild case causes so much family pain. Here are the actual shares, three worked distributions, and the statutory fixes that exist in some countries.
Invoice vs Receipt vs Quote vs Estimate: Which Do You Send?
Eight business documents get confused with each other constantly, and picking the wrong one delays payment or creates a tax problem. Here is what each one actually does, in the order a real project uses them.
Getting Your Favicon to Show in Google Search Results
Google has a short list of favicon requirements and no way to submit one. Here is the checklist, how to verify each item, and why the fix you shipped this morning will not appear today.
EXIF, IPTC and XMP: What Lives in Each Metadata Standard
Three metadata standards sit inside the same photo file, and they overlap in ways that make software disagree about your caption and your copyright. Here is the division of labour, field by field.
Cutting Weight for a Meet: A Practical Guide That Doesn't Pretend It's Free
Most cutting advice sells you the protocol and hides the invoice. Here is what actually moves on the scale, what a cut costs you on the platform, and how to work out whether the trade is worth making.
Aquarium Water Change Schedule: How Much and How Often
Twenty-five percent weekly is a starting guess, not an answer. Here is the arithmetic that tells you what your tank actually needs, and how to do the change without stressing the fish.
The Hours of Service Violations That Actually Show Up on Inspections
Most hours-of-service violations are not deliberate. They are paperwork, timing and habit problems that repeat across thousands of inspections. Here is what gets written up, why, and the end-of-day routine that heads off most of it.
Dense, Gummy Sourdough: Under-Proofed or Over-Proofed?
A tall tight loaf with a gummy band and a torn side is a different problem from a flat pale one with a dull score. Here is how to read your own crumb and fix the timeline that caused it.
What Actually Happens When You Overload an RV
Overloading an RV does not usually end in a dramatic failure on day one. It ends in a tyre at 3pm on a hot climb, brakes that will not hold a descent, and a fact you would rather not be holding after a crash.
Digital Passport Photo Specs: Pixels, File Size, Upload Errors
Two errors account for most failed passport photo uploads: file too large and resolution too low. Here are the real pixel and file size specs, plus the EXIF orientation bug that sends a perfectly good photo in sideways.
Where the Madhhabs Disagree on Faraid, and Where They Don't
Two relatives can run the same family through two calculators and get two answers. Usually that is not a bug. Here is what the schools agree on, which is most of it, and the handful of questions where they part company.
Invoice Numbering Systems That Don't Fall Apart in Year Three
Your ninth invoice is easy. Your ninetieth is where the cracks show. Four numbering schemes, what tax authorities actually ask for, and how to fix a sequence you have already broken.
Designing a Favicon That's Still Readable at 16 Pixels
A 16x16 favicon is 256 pixels of information. Your logo has more detail than that, so icon design is subtraction rather than scaling. Here is the ladder to climb down and the numbers that decide it.
Document Metadata: What PDFs, Word and Excel Files Record
Every document you send carries a hidden record of who made it, what software they used and sometimes what they deleted. Here is what lives where, and how to clear it before the file leaves your hands.
IPF GL Points Explained: The Formula the IPF Scores You On
GL points decide Best Lifter at every IPF-affiliated meet, and the formula behaves nothing like Wilks or DOTS at the edges of the bodyweight range. Here is what the numbers do and why two federations can rank the same pair of lifters in opposite orders.
Aquarium Filter GPH and Turnover: What You Actually Need
Rated GPH is measured on an empty box with no media and no lift. Here is how to translate the number on the packaging into filtration your tank will actually get, tank size by tank size.
The Adverse Driving Conditions Exception: Two Extra Hours, and the Test You Have to Pass
Two extra hours sounds simple until an officer asks why you thought the snow was unforeseeable. This walks through the knowledge test, the ELD annotation, a full worked timeline, and the misuses that get drivers cited.
Convert a Yeast Recipe to Sourdough: Arithmetic and Timing
Swapping a packet of instant yeast for a lump of starter is the easy half. The half that decides whether your loaf works is subtracting the starter's own flour and water, and rewriting a 90-minute rise into a six-hour one.
How to Weigh Your RV at a CAT Scale and Actually Understand the Ticket
A truck stop scale will hand you four numbers in eight minutes. Here is exactly how to get on it, how many passes you need, and what each line on the ticket means for a trailer, a fifth wheel or a motorhome.
How to Take a Baby Passport Photo at Home Without Stress
Newborn and infant passport photos follow looser rules than adult ones, but only in specific ways. Here is the shot setup, the age bands, the hand problem, and the sizing arithmetic that decides whether it passes.
Adopted Children, Step-Children and Inheritance in Islam
An adopted or step-child is not an automatic heir under Islamic inheritance rules. That is a statement about lineage rather than about family, and there are four established mechanisms that do provide for them.
Adding VAT or GST to a Freelance Invoice Without Getting It Wrong
Charging the wrong tax is worse than charging none. Here are the fields a UK VAT invoice and an Indian GST tax invoice must carry, why place of supply decides your tax split, and where US freelancers actually stand.
apple-touch-icon: The Size, the Safe Area, and What iOS Does
One 180 by 180 PNG at your site root covers modern iOS. The interesting part is what iOS does to it afterwards: composites transparency onto black, applies its own corner mask, and caches the result harder than anything else on the device.
Do Screenshots Have Metadata? What Phones and Laptops Record
A screenshot carries no GPS and no camera settings, which makes it feel safe. The timestamps, the filename, the pixel dimensions and the visible pixels themselves tell a different story.
Choosing a Powerlifting Weight Class: The Maths Nobody Runs
Before you enter a meet at 83 instead of 93, there is a calculation worth doing. It takes two minutes, it uses your own numbers, and it usually says the cut is not worth what you think it is.
Aquarium Algae: Identify Which One You Have, Then Fix It
Scrubbing algae without changing what caused it is a treadmill. Here is how to identify the six common types by look and feel, what each one is telling you, and the order to pull the levers.
The 150 Air-Mile Short-Haul Exemption: Who Qualifies and How You Lose It
Most drivers who bust the short-haul exemption do it by 20 minutes or by a misunderstanding of what an air mile is. Here are the three conditions, the conversion nobody spells out, and what happens the day you fall outside.
Sourdough Hydration Explained: 65%, 75% and 85% in Grams
Baker's percentage is simple until the levain arrives and quietly changes your number. Here is the full calculation in grams, plus what 65%, 75% and 85% actually feel like in the hand.
Towing Capacity vs Payload: Why Your Half-Ton Can't Tow the Trailer It's Rated For
Your truck's tow rating and your truck's payload are two different ceilings, and payload is almost always the one you hit first. Here is the maths that tells you which trailer you can really pull.
Passport and Visa Photo Sizes by Country: mm, Inches, Pixels
One table covering photo dimensions, head height, background colour and pixel size for seventeen countries and schemes, plus the two structural families every format belongs to and why head height fails more applications than size does.
How Much Does a Wife or Husband Inherit in Islam?
A husband takes a half or a quarter. A wife takes a quarter or an eighth, and co-wives divide one share between them. The unpaid dower and the family home complicate all of it, usually more than the fraction itself does.
Invoice Payment Terms Explained: Net 30 and What It Costs You
Net 30 does not mean the money arrives on day 30. Here is what each common payment term does, the arithmetic behind early-payment discounts, and the wording that removes the ambiguity clients rely on.
favicon.ico, PNG or SVG: What to Actually Ship in 2026
Old generators hand you 26 files and eleven link tags. You need three files and four tags. Here is what each format buys you, why .ico still belongs at the root, and where SVG quietly falls apart.
Do Your Photos Have Your Location? How to Check Before You Post
Most social networks throw away the GPS tags in your photos. Email, cloud links and marketplace uploads usually do not. Here is how to look inside your own files and see exactly what they are carrying.
Wilks, Wilks 2, DOTS and GL: Why Your Score Changed and Which One Counts
Your total did not move but your coefficient score did. Here is the timeline behind Wilks, Wilks 2, DOTS and IPF GL points, what each refit actually changed, and which number is worth tracking.
How to Cycle a Fish Tank Properly (Fishless, With Numbers)
A fishless cycle done properly takes three to six weeks and needs exactly three things: an ammonia source, a liquid test kit, and patience. Here is the protocol with actual numbers attached.
The 14-Hour Driving Window: What Stops It, What Doesn't, and How to Protect It
Your 14 is the least forgiving clock in Part 395 because almost nothing pauses it. Here is what actually starts it, the three exceptions that touch it, and how to plan a day backwards from an appointment.
Browse by topic
Each topic pairs with the tool it was written around.
Aquariums and Fishkeeping
- Reading Your Aquarium Test Kit: What Every Number Means
- Aquarium Water Change Schedule: How Much and How Often
- Aquarium Filter GPH and Turnover: What You Actually Need
- Aquarium Algae: Identify Which One You Have, Then Fix It
- How to Cycle a Fish Tank Properly (Fishless, With Numbers)
Baking
- Sourdough Discard: What to Do With It, and When to Bin It
- Dense, Gummy Sourdough: Under-Proofed or Over-Proofed?
- Convert a Yeast Recipe to Sourdough: Arithmetic and Timing
- Sourdough Hydration Explained: 65%, 75% and 85% in Grams
Invoicing and Getting Paid
- Invoice vs Receipt vs Quote vs Estimate: Which Do You Send?
- Invoice Numbering Systems That Don't Fall Apart in Year Three
- Adding VAT or GST to a Freelance Invoice Without Getting It Wrong
- Invoice Payment Terms Explained: Net 30 and What It Costs You
Islamic Inheritance and Faraid
- Grandchildren and the Orphaned Grandchild in Islamic Inheritance
- Where the Madhhabs Disagree on Faraid, and Where They Don't
- Adopted Children, Step-Children and Inheritance in Islam
- How Much Does a Wife or Husband Inherit in Islam?
Passport and ID Photos
- Glasses, Hats and Clothing: Passport Photo Rules People Get Wrong
- Digital Passport Photo Specs: Pixels, File Size, Upload Errors
- How to Take a Baby Passport Photo at Home Without Stress
- Passport and Visa Photo Sizes by Country: mm, Inches, Pixels
Photo Metadata and Privacy
- EXIF, IPTC and XMP: What Lives in Each Metadata Standard
- Document Metadata: What PDFs, Word and Excel Files Record
- Do Screenshots Have Metadata? What Phones and Laptops Record
- Do Your Photos Have Your Location? How to Check Before You Post
RV and Towing
- Tongue Weight: How to Measure It, Why 10 to 15 Percent, and What Sway Really Is
- What Actually Happens When You Overload an RV
- How to Weigh Your RV at a CAT Scale and Actually Understand the Ticket
- Towing Capacity vs Payload: Why Your Half-Ton Can't Tow the Trailer It's Rated For
Strength Sports
- How to Read a Powerlifting Results Sheet (and Work Out Who Really Won)
- Cutting Weight for a Meet: A Practical Guide That Doesn't Pretend It's Free
- IPF GL Points Explained: The Formula the IPF Scores You On
- Choosing a Powerlifting Weight Class: The Maths Nobody Runs
- Wilks, Wilks 2, DOTS and GL: Why Your Score Changed and Which One Counts
Trucking and Hours of Service
- The DOT 30-Minute Break Rule: When It's Due and What Actually Counts
- The Hours of Service Violations That Actually Show Up on Inspections
- The Adverse Driving Conditions Exception: Two Extra Hours, and the Test You Have to Pass
- The 150 Air-Mile Short-Haul Exemption: Who Qualifies and How You Lose It
- The 14-Hour Driving Window: What Stops It, What Doesn't, and How to Protect It