How Much Protein for Muscle Gain
To build muscle, aim for about 1.6 to 2.2 grams of protein per kilogram of body weight daily. Learn how to hit that target, spread it across meals, and time it around training.
Aisha Karim · 3 min read
Guides & tutorials
Practical guides, how-tos and comparisons to get the most out of our free online tools.
April 28, 2026
How to Calculate Cost Per Use (and Buy Better Quality)
The sticker price lies. Cost per use — price divided by expected uses — reveals when the expensive, durable option is actually the cheaper one, and when it is not.
Camille Laurent · 4 min read
April 27, 2026
What Size Heater Do I Need? Sizing BTUs by Room and Climate
Size a heater from room area and your climate: a BTU-per-square-foot rule gives the heat output, with watts and kW for electric units.
Marco Bianchi · 4 min read
Best Time to Wake Up: Using Sleep Cycles
Sleep runs in cycles of about 90 minutes. Waking at the end of a cycle can help you feel more refreshed. Here's how to count back from your wake time.
Sofia Nunes · 3 min read
April 24, 2026
How Unix File Permissions Work: Reading 755 Without Guessing
Read is 4, write is 2, execute is 1, and each of the three digits describes a different party. The part most explanations get wrong is what the execute bit does on a directory — it grants traversal, not the right to run anything.
Daniel Okonkwo · 7 min read
How Many Pizzas for a Party? Slice & Pie Calculator Guide
Work out how many pizzas to order for a party: slices per guest, slices per pizza, and the simple formula that ties them together.
Marco Bianchi · 3 min read
How to Calculate Rental Yield (Gross vs Net)
How to calculate rental yield: the gross formula (annual rent ÷ price), the net version after costs, and what counts as a good yield.
Camille Laurent · 3 min read
April 23, 2026
IVF Dating Is the One Case Where the Date Is Actually Known
Every other pregnancy is dated from an estimate. After IVF, fertilisation is timed to the hour, so gestational age is arithmetic: 266 days from fertilisation, minus the embryo's age at transfer. Here is the derivation for day-3, day-5 and day-6 embryos, why frozen and fresh transfers use the same rule, why an early scan rarely moves an IVF date, and what the two-week offset on a scan report means.
Sofia Nunes · 12 min read
EV vs Gas: Comparing the Real Annual Running Cost
How much does it actually cost to fuel an EV versus a gas car each year? We compare cost per mile from electricity and gasoline, plus the factors that swing the answer.
Marco Bianchi · 4 min read
What Is Cycling FTP (Functional Threshold Power)?
FTP is the highest power in watts you can hold for about an hour. Learn how to test it, why watts per kilogram matters, and how it guides training zones.
Aisha Karim · 3 min read
April 22, 2026
Am I Overweight? Why One Number Cannot Say
BMI reads muscular bodies as heavy and cannot see where fat sits at all — which is exactly why the waist measures exist. Here are the published waist and waist-to-height thresholds, a worked case where BMI and waist give opposite answers, an honest account of the contested mortality curves, and the 2025 shift toward defining obesity by adiposity and organ function rather than by a ratio.
Sofia Nunes · 13 min read
What Is an Index Fund? How Passive Investing Works
An index fund tracks a whole market instead of betting on winners. Learn how tracking works, why diversification and low fees matter, and how it stacks up against active funds.
Camille Laurent · 4 min read