How to Pace a 5K
Divide your goal time by 5 to get the pace to hold, then run even splits. Here's how to find your target pace, train for it, and race it well.
Aisha Karim · 2 min read
Guides & tutorials
Practical guides, how-tos and comparisons to get the most out of our free online tools.
August 20, 2025
August 19, 2025
Bandwidth and Speed: Mbps vs MB/s Explained
Why your 100 Mbps plan downloads at 12.5 MB/s, the bits-versus-bytes ÷8 rule, and how to turn a connection speed into a real download time.
Daniel Okonkwo · 4 min read
August 18, 2025
How Much Does It Cost to Charge an Electric Car?
Charging cost is energy added times your electricity price. Here's the sum, home vs public charging, cost per 100 miles, and how it compares to gas.
Camille Laurent · 3 min read
August 15, 2025
Colour Schemes Are Geometry on a Wheel — and the Wheel Is Wrong
Complementary, triadic, analogous and split-complementary are just rotations: add 180°, 120°, 30° or 150° to a hue. The arithmetic is trivial. The problem is that the HSL hue circle is not perceptually uniform — yellow and blue at the same HSL lightness differ in luminance by 12.85 times — so a generated palette has to be contrast-checked afterwards.
Daniel Okonkwo · 15 min read
August 14, 2025
Screen Resolution, Pixel Density, and the Numbers Marketing Uses
A diagonal plus an aspect ratio gives you width and height by Pythagoras, and the answer is not what the marketing implies: a 27-inch 21:9 has 16.2% less area than a 27-inch 16:9. Then pixels per degree, which shows the highest-PPI phone is not the sharpest thing you own.
Daniel Okonkwo · 17 min read
How to Simplify a Ratio
Divide both sides by their greatest common divisor. Here's what a ratio is, how to reduce it, why units must match first, and how to compare ratios.
Lena Hoffmann · 3 min read
August 13, 2025
SQL Formatting and the IN Clause That Breaks Production
Building an IN list by string concatenation is both the classic injection vector and a performance cliff. Parameterisation fixes the first structurally, because the plan is compiled before any value arrives. The second needs arithmetic: the vendors' documented parameter ceilings, and what a query whose text changes with every list length does to a plan cache.
Daniel Okonkwo · 19 min read
Scientific Notation Explained
Scientific notation writes huge and tiny numbers as a value times a power of ten. Here's how to write it, read the exponent, and convert back.
Lena Hoffmann · 3 min read
August 12, 2025
YAML Looks Friendly and Bites
YAML is JSON plus a type-inference layer, and the inference is the dangerous part. The same file run through a YAML 1.2 parser and a YAML 1.1 parser: no is a string in one and false in the other, 01234 is 1234 in one and 668 in the other, and 12:30:00 is a number in one of them.
Daniel Okonkwo · 17 min read
What Is MPG (and How to Improve It)?
MPG is how far a car goes on a gallon — higher is better. Here's what it means, how it relates to L/100 km, why your real figure is lower, and how to improve it.
Marco Bianchi · 3 min read
August 11, 2025
How Many Steps to Burn Calories?
Walking burns roughly 0.04 calories a step. Here's what 10,000 steps really burns, what changes the number, and whether 10,000 is a magic figure.
Aisha Karim · 2 min read
August 8, 2025
JSON Is Simpler Than You Think, and That Is the Problem
JSON has no integer type, no date type, no comments and no schema. Every one of those absences produces a specific bug: a 19-digit ID comes back off by 21, a timestamp becomes a string nobody agreed on, NaN cannot be written down, and duplicate keys are legal. All of it run, in two languages.
Daniel Okonkwo · 19 min read