# All online calculators

- Date and interval
Adds and subtracts a specified time interval to the specified date

- Date and number of working days (for Russia)
Calculator calculates the date of the initial date and the number of working days. Taking into account weekends, holidays and weekend shifts at work days, according to the published decrees of the government of the Russian Federation. Created by user's request.

- Date by the Julian Day Number
Displays Gregorian calendar date corresponding to Julian Day Number

- Date plus days
This online calculator computes the result of addition/subtraction of the given number of days to the given date.

- Date to timestamp converter
This calculator converts date to epoch timestamp in milliseconds, that is, milliseconds since standard epoch of 1/1/1970, as used, for example, in Javascript.

- Day of week by date
This online calculator outputs day of week for given date

- Days between dates. A historical version.
Calculates number of days between two dates taking in account the date of transition to Gregorian calendar.

- Days count in several date spans
The calculator gives total number of days in date span list. Each date span is defined by start date and end date. The calculator can exclude multiple date date span intersections.

- Density of oil
Recalculation of density of oil for different temperature and pressure values. Formulas are taken from Russia's GOST R 8.610-2004. "State system for ensuring the uniformity of measurements. Density of oil. The tables for recalculation" standard

- Derivative
It finds one variable function derivative. Step by step differentiation solution is also provided.

- Determinant of 3x3 matrices
This calculator calculates the determinant of 3x3 matrices

- Determinant of a matrix
This online calculator computes determinant of a matrix, using it's definition

- Determining air humidity with psychrometric method
- Dew point
This calculator determines dew point from given temperature and relative humidity of air

- Digital image size in pixels and photo print size
This article is about relation between image size in pixels and photographic print size. First, it recommends photographic print size for given digital image dimensions in pixels. Second, it finds resulting pixels per inch value for printed digital image with known linear and pixel dimensions.

- Dimensiones de pantalla y proporción de aspecto
Esta calculadora en línea encuentra dimensiones de pantalla - altura y ancho, dado el valor diagonal y proporción de aspecto.

- Direct observation error analisys
Calculates error of direct measurements for given measured value series and confidence interval.

- Distance calculator