# All online calculators

- 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

- Determination of the baby's sex
It's unscientific, but it surprisingly works.

- 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.

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

- Discount calculator
This online calculator finds the discount from the sale price and the usual price, the sale price from the discount and the usual price and the usual price from the sale price and the discount

- Display aspect ratio and dimensions
This online calculator finds screen dimensions - height, width and area, given the diagonal value and aspect ratio.

- Distance across the surface vs distance through the Earth
This calculator calculates distance across the surface of the Earth and distance through the Earth for given two points, then compares them.

- Distance and midpoint between two points
This online calculator find distance and midpoint between two points in cartesian coordinates.

- Distance between two cities
Calculates the distance between the two cities. Uses the directory of geographical city coordinates for the calculation.

- Distance calculator
Calculates distance between two geographic coordinates using haversine formula.

- Distance through the Earth
This calculator calculates the distance from one point on the Earth to another point, going through the Earth, instead of going across the surface.

- Dollars to rubles and vice versa by Central Bank of Russia exchange rate
- Doppler Effect in sound
Calculation of frequency and wavelength change for a moving source

- Double exponential smoothing
Description and example of the double exponential smoothing

- Earth Radius by Latitude (WGS 84)
This online calculator calculates Earth radius at given latitude using WGS 84 reference ellipsoid