Why UtilityLab exists
Most online calculators are black boxes wrapped in advertising. You enter numbers, a result appears, and there is no way to tell whether the formula is right, which costs are included, or where your data went. For a mortgage or rental decision, that is not good enough.
UtilityLab takes the opposite approach. Each tool has one job, prints its formulas, runs entirely in the browser, and includes a written explanation of what it does and does not model. If a result surprises you, you can trace it line by line.
How tools are built
- Static and local. The site is static HTML, CSS and a small amount of JavaScript. Calculator inputs never leave the device.
- Tested formulas. Every calculation has unit tests, including the solver, sensitivity grid, repeat engine and share-link encoding.
- Documented assumptions. Each guide states the model's boundaries in plain language. No invented market data, rent comps or “average” returns.
- Accessible by default. Keyboard navigation, visible focus, 44px targets, reduced-motion support, 320px layouts and dark mode.
- Printable. Results can be printed as a one-page brief without the site chrome.
Who runs it
UtilityLab is built and maintained independently in Kolkata, India. It is a small operation: one person, a public repository of formulas, and a preference for shipping a tool that works over a catalog that looks busy.
The first tool is a BRRRR calculator because the strategy is popular and the arithmetic is frequently presented without its assumptions. More tools will be added only when their formulas, tests and documentation are ready.
Corrections and contact
If you find a formula error, an accessibility problem, or a result that does not match the documented method, emailcontact@wheelchairrampcalculator.com. Include the tool, the inputs, and what you expected. Corrections are treated as bugs, not feedback.
For privacy details, see the privacy page. For tool questions, see the FAQ.
UtilityLab is a publisher of planning models. It is not a lender, broker, appraiser, tax adviser or investment adviser. Nothing on the site is financial, tax or legal advice.