How Many Square Metres Are in an Acre?
One acre is about 4,047 square metres; a hectare is exactly 10,000. Learn the conversions and how land-area units relate.
Marco Bianchi · 4 min read
Guides & tutorials
Practical guides, how-tos and comparisons to get the most out of our free online tools.
May 26, 2026
May 25, 2026
Real vs Nominal Return: Why Subtracting Inflation Is the Wrong Answer
At 7 percent nominal and 3 percent inflation the real return is 3.883 percent, not 4. The Fisher equation divides, it does not subtract — and over 30 years the shortcut overstates a $10,000 pot by $1,072.
Camille Laurent · 6 min read
Luggage Weight and Size Limits: How Airlines Actually Measure Your Bag
Linear dimensions, volumetric weight and typical cabin and checked limits explained, so your bag clears the gate without a surprise fee.
Marco Bianchi · 5 min read
How to Calculate a Wilks Score to Compare Powerlifting Totals
Use the Wilks coefficient to compare powerlifting totals fairly across bodyweights, so a lighter and heavier lifter can be ranked.
Aisha Karim · 4 min read
Fixed vs Variable Rate Mortgage: Which Should You Choose?
Compare fixed and variable rate mortgages on certainty, cost, and risk, and see which suits your budget, timeline, and tolerance for change.
Camille Laurent · 4 min read
May 22, 2026
What the APR Includes That the Rate Does Not — and Why 6 % Can Beat 7.5 % Backwards
A 6 percent loan with a 3 percent fee and compulsory insurance carries an APR of 10.7 percent and costs $486 more than a 7.5 percent loan with no fees at all. The APR is the figure that catches it.
Camille Laurent · 6 min read
Student Loan Repayment Strategies: Five Routes Through the Same $30,000
Standard, extended, overpaid, refinanced or income-linked: the same $30,000 at 5 percent costs anywhere from $35,716 to $52,613. And where a scheme writes the balance off, overpaying can cost $11,178 and buy nothing.
Camille Laurent · 6 min read
Should You Pay Off a Car Loan Early? The Rule, and the Three Exceptions
Settling a $20,000 car loan at 7 percent two years in saves $1,431 of interest — but only $663 of that is a real gain if the cash was earning 4 percent, and precomputed interest can take $62 or more off the top.
Camille Laurent · 6 min read
How Much Rice Per Person? Portions and Water
A good rule for rice is about 75 g of dry rice per person as a side, or 90 g as a main. Learn the standard water ratio and how to scale rice for any number of people.
Marco Bianchi · 4 min read
How Much Caffeine Is Safe Per Day?
The 400 mg daily guideline for adults, how much caffeine is in coffee, tea, cola and energy drinks, and why sensitivity varies from person to person.
Sofia Nunes · 3 min read
May 21, 2026
How to Write a robots.txt: Directives, Matching, and What It Cannot Hide
Four directives, two wildcards, one file at the host root. It is a crawl instruction and nothing more — it does not remove a page from search results, it does not restrict access, and it publishes every path you list in it.
Daniel Okonkwo · 9 min read
How to Write a Cron Expression: Five Fields and the OR Rule Nobody Mentions
Minute, hour, day of month, month, day of week. The traps are that a step is a stride through a range and not an interval, and that the two day fields are combined with OR — so 0 0 1 * 1 fires on the 1st and on every Monday.
Daniel Okonkwo · 9 min read