Editorial policy
A calculator is only useful if you can see what it is doing. That means showing the formula, naming the assumptions, and being honest about where the answer starts to get fuzzy.
How we build calculator pages
Each calculator starts with the formula, the default assumptions, and a few examples we can check by hand. If there is a public source for the math, we cite it on the page. Tax tools get checked against IRS and Social Security data. Mortgage pages lean on CFPB explanations. Health calculators use public health or medical references where they fit.
Sources we prefer
We prefer primary sources: government agencies, standards bodies, medical organizations, academic papers, and official documentation. Some calculators use a rule of thumb rather than a formal standard. When that is the case, the page should say so plainly.
When we update pages
Some numbers change every year. Tax brackets, Social Security wage bases, contribution limits, and public health guidance all need another look when the source changes. Other calculators get reviewed when we change the formula, fix a bug, or receive a correction that we can reproduce.
Corrections
If something looks wrong, send us the page URL, the numbers you entered, the result you got, and what you expected instead. That is the fastest way for us to reproduce the issue and fix it.
You can send corrections through the contact page.
Important limits
Calculator results are estimates. They can help you think through a decision, but they are not a substitute for a qualified financial, tax, legal, medical, or professional adviser. Local rules, fees, taxes, medical history, lender policies, and missing details can all change the real answer.