Unit Converter
Every unit of science, engineering and the field: length, area, mass, pressure, angle and slope, permeability, coordinates and more.
Converts between all common units of 30 quantities with the exact factors of the international standards: length, area (including the Iraqi dunam and olk), volume and barrels, mass and carats, density, API gravity and mud weight, pressure and stress, pressure and geothermal gradients, temperature, angle, dip and slope in percent and ratio, time and geological time, speed and sonic slowness, gravity in milligal, force, energy, power, flow, permeability in darcy, hydraulic conductivity, viscosity, concentration, resistivity, conductivity and salinity, magnetic field in nanotesla, radioactivity and dose, frequency, data and fuel. It also converts coordinates between decimal degrees, degrees–minutes–seconds and UTM, works out map scales, and turns ions between mg/L and meq/L with the ionic balance. Free for everyone.
Overview
Every value is converted through the SI unit of its quantity with the exact factors of NIST Special Publication 811 and ISO 80000, and shown at once in every unit of the quantity. Scales that are not simple multiples are converted by their defining equations: temperature, slope in percent and ratio, API gravity, sonic slowness and velocity, resistivity and conductivity, fuel consumption.
Coordinates are converted on the WGS 84 ellipsoid with the Krüger series used by national mapping agencies, accurate to well under a millimetre within a UTM zone.
What you enter · What you get
What you enter
- A value and its unit
- Latitude and longitude or a UTM position
- A map scale and distances
- Ion concentrations
What you get
- The value in every unit of the quantity, ready to copy
- Decimal, DMS and UTM coordinates
- Ground and map distances
- meq/L and the ionic balance error
How it works in the field
Method and equations
Linear units
x [to] = x [from] × f[from] / f[to], with f the exact factor to the SI unit.
Slope
Percent slope is 100 × tan θ; ratio 1 : n is cot θ.
API gravity
From specific gravity at 60 °F.
Temperature
Through kelvin.
Accuracy and error limits
- Conversions use the exact factors of the SI and of the international yard and pound (1959); results are exact to the 12 significant figures shown, so the error comes only from the value entered.
- A few units are conventional rather than exact: the barrel of oil (158.987 L), API gravity defined at 60 °F, the Iraqi dunam (2 500 m²) and the olk, and geological time units, which follow the definitions shown in each list.
- To avoid errors: keep the number of significant figures of the original measurement, and check that a pressure is gauge or absolute and a temperature difference is not converted as a temperature.
Who uses it
Standards and references
- Thompson, A. & Taylor, B.N. (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811.
- ISO 80000 (2019–2022). Quantities and units.
- BIPM (2019). The International System of Units (SI), 9th edition.
- Karney, C.F.F. (2011). Transverse Mercator with an accuracy of a few nanometers. Journal of Geodesy, 85, 475–485.
- API (2012). Manual of Petroleum Measurement Standards, Chapter 11.1.
- IUPAC (2021). Standard atomic weights of the elements.
- Hem, J.D. (1985). Study and Interpretation of the Chemical Characteristics of Natural Water. USGS Water-Supply Paper 2254.
At a glance
- Category
- Field geology
- Runs on
- Phone, tablet and desktop browser
- Export
- Copy any value
- Access
- Free
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