Methodology
Every tool here follows the same few rules. This page says what they are, how each tool is tested before it goes live, and where the tools stop.
Two readings, never one
Most project figures have a convenient reading and a careful one, and both are usually defensible. The sum of the most likely estimates is a total; the total the project reaches four times in five is another. Where a figure has two readings, the tools show both, side by side, and say why they differ. The distance between them is usually the finding.
Every assumption is written down
Each result ends with a list of what it assumed: the method and its formula, which rows were left out and why, what each setting was set to, how figures were rounded. None of it is hidden in the arithmetic. If the list says something you disagree with, change the setting and the answer changes with it.
Problems are named, not quietly fixed
Findings come in three kinds: a problem, something worth checking, and a note, each with a count and examples from your own file. A row a tool cannot use is left out and listed, never guessed at, and a figure like 3,5 that means different things in different countries is refused with a reason rather than read one way. A repair made silently is how a spreadsheet produces a confident wrong answer.
Simulations are seeded
Where a tool simulates, it says how many runs it made and with what seed, and the same inputs always give the same answer, on any computer. Randomness is a way of doing the arithmetic, not a source of new results each time you reload.
Generic methods, named plainly
Critical path, earned value, three-point estimating and the rest are the common property of the profession. The tools use their generic names, cite where a convention comes from, and say where software packages disagree about one. Nothing here is affiliated with, endorsed by or a substitute for any certification body or its publications.
The tools assist; people decide
No tool here decides anything with consequences: whether a project is healthy, how much contingency to hold, which risk to accept. They calculate, check and compare, and show their working. The judgment about what the answer means for your project stays with the person accountable for it.
How each tool is tested
Every tool’s arithmetic is checked by an automated suite of worked examples, where the right answer was worked out by hand, or from a formula that shares no code with the tool, before the tool was run against it. All of them run before any change goes live, for all 45 tools and the file reader they share.
Every tool is also loaded with the files that break software: an empty file, a single row, the wrong file entirely, rows with values missing or extra, cells holding errors, formulas and thousands of characters, text saved in older encodings, and files of tens of thousands of rows. Each has to end in either a result or a plain sentence saying what is wrong with the file, never a crash.
The date at the foot of each tool page is when its method and tests were last checked. Every tool was checked on 12 September 2026.
The tests show that each tool does what it says. They cannot show that what it says is what your project needs, which is why the assumptions are always on the page. No outside body has reviewed or certified these tools.
Your file stays with you
Every tool runs inside your browser. Your file is read there, worked on there, and never sent anywhere, and every page tells your browser to refuse any connection to another website, so it could not be sent even by mistake. The privacy page explains how that works and how to check it yourself in ten seconds.
When something looks wrong
If a result looks wrong, a file will not load, or a tool is missing something you need, say so by email. Describe what happened and which tool it was; please do not attach project files. The sample data can often show the same problem.