Calculator Widget Directory

Choose a calculator, copy its embed code and add a useful yootils tool to your website.

New to this? Read the step-by-step install guide →

Attribution: the widgets are free to use on any website, commercial or not. In return, each one keeps its “Open full calculator” link and “powered by yootils” credit visible. Please don’t remove or hide them — that credit is the only thing we ask for, and it is what keeps the widgets free.

Mortgage Calculator

Finance widget — monthly payment estimate.

Unit Converter

Length, weight, volume — quick conversions.

Date Difference

Days/Weeks between two dates.

Percent Calculator

Common percent operations.

BMI Calculator

Body Mass Index calculator with metric/imperial.

Timezone Converter

Convert a datetime to a different timezone.

Loan Payment

Monthly payment for generic loans.

Compound Interest

Future value using compound interest.

Age Calculator

Exact age in years, months & days from a date of birth.

BMR Calculator

Basal metabolic rate & daily calorie needs (TDEE).

Height Converter

Convert centimetres to feet & inches and back.

Weight Converter

Convert between kg, lbs and stone.

Hex ↔ RGB

Convert colour codes between hex and RGB.

Case Converter

Transform text to UPPER, lower, camelCase, snake_case & more.

LTV Calculator

Loan to value, equity, and what it takes to reach the next band.

Pay Rise Calculator

Gross rise versus what actually reaches your account, after UK tax and NI.

Business Days

Working days between two dates, excluding weekends and UK bank holidays.

Credit Card Payoff

How long a balance takes to clear and what the interest costs.

Ratio Calculator

Simplify a ratio to its lowest terms, with each part as a percentage.

ROI Calculator

Return on investment and net profit from cost & final value.

Interest Calculator

Simple and compound interest with total amount.

Day Counter

Days until (or since) any target date.

Sleep Calculator

Suggested bedtimes or wake times based on 90-min sleep cycles.

Pace Calculator

Running pace, finish time or distance from any two inputs.

Investment Calculator

End balance with initial amount, monthly contributions & compounding.

Auto Loan Calculator

Monthly car loan payment from price, deposit, rate & term.

Probability Calculator

Single event, P(A and B), and P(A or B) calculations.

Base Converter

Convert numbers between binary, octal, decimal and hex.

Take-Home Pay

UK net salary after income tax and National Insurance.

Macro Calculator

Daily calories with protein, carb and fat targets.

Mortgage Payoff

Interest and time saved by overpaying a mortgage.

Due Date Calculator

Estimated due date and pregnancy countdown.

Body Fat Calculator

Body fat percentage via the U.S. Navy method.

Time Duration

Hours and minutes between two times, with breaks.

Savings Calculator

Savings growth with regular monthly deposits.

Protein Calculator

Daily protein target by activity level and goal.

Steps to Distance

Steps converted to miles and km by height and pace.

Sunrise & Sunset

Sunrise, sunset and daylight length for major cities.

Ideal Weight

Ideal body weight across four clinical formulas.

Week Number

ISO-8601 week number for any date.

Include the single script once per page: <script src="https://yootils.com/widgets/v7/widgets.js" integrity="sha384-+/J+UJUQkd8qBlJ2y9qW3wNk89iZUobwuVdo6dqpCvoanps684ZTa7cGCJ5L1AQc" crossorigin="anonymous" async></script>

Data: the widgets collect nothing. No cookies, nothing written to your site’s storage, and no data sent anywhere — whatever your visitors type stays in their own browser. See exactly what it does →

Accessibility: every calculator is operable by keyboard, labelled for screen readers, draws a visible focus ring, respects a reduced-motion preference, and follows your visitor’s light or dark setting unless you pin one. Colour contrast meets WCAG AA in both themes.