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.
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.
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Latest posts
One guide per tool so far. More from each cluster is on the way.
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
- 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
- Convert a Yeast Recipe to Sourdough: Arithmetic and Timing
- Sourdough Hydration Explained: 65%, 75% and 85% in Grams
Invoicing and Getting Paid
- 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
- Adopted Children, Step-Children and Inheritance in Islam
- How Much Does a Wife or Husband Inherit in Islam?
Passport and ID Photos
- 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
- Do Screenshots Have Metadata? What Phones and Laptops Record
- Do Your Photos Have Your Location? How to Check Before You Post
RV and Towing
- 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
- 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 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