There is no national septic tank size chart
Ask the internet what size septic tank a three-bedroom house needs and you will get one confident national chart. The trouble is that septic sizing in the US is not national. It is set state by state, in each state's own code — and the states do not agree.
The US changed its freight class rules in July. Most calculators didn't notice.
If you ship freight in the US, the price of a pallet depends on its freight class — and freight class depends on density. In July 2025 the rules underneath that system changed: the NMFC moved to a new density scale (Docket 2025-1, effective July 19, 2025) with 13 classes running from 50 to 400. Under the new scale, freight under 1 pound per cubic foot is class 400; at 50 pounds per cubic foot and above, it is class 50.
The duty on your invoice is never the duty you pay
Ask a US importer what duty they pay on a product and they will usually name one number: the rate in the tariff schedule. That number is almost never the whole bill.
My earthquake site said 8 quakes in 24 hours. There were 3.
DidItShake is a free US earthquake monitor built on official USGS data: a live map of every US earthquake of magnitude 2.5+ from the last 7 days, and a history page for more than 6,000 American places — recent activity, biggest recorded quakes, and long-term statistics in plain language.
The month the inflation data simply doesn't exist
I run Inflation Record, a small site that turns the US Consumer Price Index into calculators: what $100 in 1913 is worth today ($3,361.64, if you are curious), what a 2020 salary needs to be now, that kind of thing. The whole site is generated from one BLS series — CPI-U, monthly values from January 1913 onward.
The £100k tax trap, and three other machines
Every country answers "what do I actually take home?" with a completely different machine. I built four of them: AfterTaxly computes take-home pay for the UK, Australia, New Zealand and Ireland, each from that country's official rates, each checked line by line against the official calculators.
Testing Leaflet: five free calculators I run
A quick test post from my little fleet of free calculator and data sites.