Practical calculators

Choose a section, enter the values you know, and get a result with the formula and assumptions clearly shown. Every calculation runs on your device, with no account and no values uploaded.

Choose a calculator category

A result you can check

These tools expose the units, rounding and boundaries behind the answer. They handle deterministic arithmetic; professional specifications and legal rules still come from the responsible authority.

Private by construction

Your dates, dimensions, timings and vehicle values stay in the page. UtilBear records aggregate calculator-use events and optional fixed-choice feedback, never the numbers you enter or the calculated result.

What is in each section

Date and time covers the arithmetic that calendars make awkward: the gap between two dates in calendar units, weekdays between deadlines with US federal holidays optionally removed, a week of shifts totalled with unpaid breaks, calendar age, and the two notation conversions people look up most, 12-hour to 24-hour and hours and minutes to decimal.

Audio production turns a tempo into working numbers: tap a BPM, read straight, dotted and triplet delay times, build a reverb grid, convert between samples and milliseconds at your session rate, measure a pitch interval in semitones and cents, and combine speaker impedances in series or parallel.

Print and pixels moves between an image and paper: pixel density from a print size, print size from a density, the canvas a document needs, bleed added on all four edges, and proportional scaling that holds an aspect ratio. Garage covers tires, wheels and drivetrains, from reading a tire label through compression ratio, displacement, gearing and injector flow. AI API costs turns the prices you were quoted into what a call and a run cost, estimates tokens from words, and reports what a context window has left once the answer has its room.

Every page shows its working

Each calculator states the formula it used and names the assumption behind the answer where one exists. A tire calculator works from the size printed on the sidewall rather than a tape measure on a loaded tire; a business-day count says which endpoint it includes; a time card separates hours above a threshold without deciding whether they are overtime.

That is deliberate. A number you cannot check is a number you cannot defend, and most of these calculations feed something that matters: an invoice, a deadline, a part order or a build. Where a result depends on a specification, a regulation or a manufacturer’s figure, the page says so instead of implying an authority it does not have.

Frequently asked questions