# All online calculators

- Random Letters Generator
This online generator just generates specified number of symbols, randomly selecting them from given set of symbols

- Raoult's Second law and the freezing temperature.
Calculation of boiling point and crystallization (freezing) of non-electrolyte solutions.

- Rectangle area calculation by perimeter
Rectangle area calculation with known perimeter and aspect ratio

- Region determination by the registration plate
- Regular expression tester
This online calculator allows user to experiment with regular expressions.

- Regular polygon area from circumcircle
Calculates the area of the circumcircle and of the regular polygon from radius of circumcircle and number of sides

- Regular polygon, number of sides and length of side from incircle and circumcircle radii
This online calculator finds number of sides and length of side of regular polygon given the radii of incircle and circumcircle

- Regular polygon. Incircle and circumcircle
This online calculator determines parameters of circumcircle and incircle of a regular polygon

- Relation between two numbers
Different relations between two numbers. Created by user's requst

- Relations between the mass, the length, the width and the area density (surface density) of the fabric
This online calculator calculates the mass of the fabric given the length, the width and the area density (surface density); the length of the fabric given the mass, the width and the area density; the width of the fabric given the mass, the length and the area density; the area density given the mass, the length and the width

- Relative humidity to absolute humidity and vise versa calculators
First calculator converts relative humidity to absolute humidity for given temperature and barometric pressure. Second calculator converts absolute humidity to relative humidity for given temperature and barometric pressure

- Relative luminance and contrast ratio
Two calculators evaluate the relative luminance and contrast ratio for given colors.

- Release Date Countdown gadget
This calculator allows you to configure the release date or event you want to track and use it as countdown gadget via new "Sharing" functionality

- Remove duplicates
The calculator removes duplicates from an element list.

- Repeated Word Heatmap
This calculator can help avoid unwanted word repetition in prose. It counts the number of occurrences of each word in the document, both globally, and within the "sliding window" distance before and after each word. It highlights the words which are used frequently near each other..

- Repeated Word Heatmap
This calculator can help avoid unwanted word repetition in prose. It counts the number of occurrences of each word in the document, both globally, and within the "sliding window" distance before and after each word. It highlights the words which are used frequently near each other..

- RGB - HSV and HSV - RGB converter
This calculator converts RGB color to HSV color and vise versa

- Roman numerals
Converter of Roman numbers and decimal numbers

- Root and power
This calculator outputs desired root and power of entered number

- Russian Central Bank Currency Rates
Russian Central Bank Currency Rates