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Metric system calculators:

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Weight (kg) / volume (liters) conversions Length conversions Temperature conversion (°C, °F, K) Surface / area conversions Mass / weight conversions Light unit conversions Conductivity conversions Liquid volume conversions
Convert between various measurement units and standard Metric System (SI) units.

Weight (kg) / Volume (liters) Conversion

Enter the weight in kilograms to get the equivalent volume in liters, or vice versa. These figures are approximate estimates meant as a practical rule of thumb for aquarists and may vary slightly depending on grain size and moisture.
kg Loire river sand (quartz) (25 kg = 18 l) liters
kg Coral sand (aragonite) (20 kg = 18 l) liters
kg Maerl sand (coralline) (15 kg = 10 l) liters
kg Aqualit (22 kg = 30 l) liters
kg Natalit (granules) (5 kg = 3 l) liters
kg Pozzolan (lava gravel) (15 kg = 21 l) liters
kg Volcanic rock (lava rock) (23 kg = 35 l) liters
kg Clay (25 kg = 20 l) liters
kg Iron-rich clay balls (Laterit) (16 kg = 15 l) liters

Length Conversion

Enter a number in either of the 2 columns to convert the length to the other unit. The value in the middle is the conversion factor.

inches (in) 25,4 millimeters (mm)
inches (in) 2,54 centimeters (cm)
feet (ft) 30,48 centimeters (cm)
feet (ft) 0,3048 meters (m)
yards (yd) 0,9144 meters (m)
miles (statute = mi) 1,609344 kilometers (km)
nautical miles (nmi) 1,852 kilometers (km)
Did you know? A fish's standard length (SL) is measured from the tip of the snout to the base of the caudal fin, excluding the tail fin itself.

Temperature Conversion (°C, °F, K)

As a quick reference, 25 °C equals 77 °F, and 81 °F is approximately 27.2 °C.
 °Fahrenheit   (t°-32)*5/9   °Celsius   or Kelvin 

Surface / Area Conversion

Note: 1 hectare (ha) = 100 ares (a) = 10,000 m²
square inches (in²) 6.4516 square cm (cm²)
square feet (ft²) 0.09290304 square meters (m²)
square yards (yd²) 0.8361274 square meters (m²)
square miles (mi²) 2.589988 square kilometers (km²)
acres (acre) 0.4046873 hectares (ha)
Note: multiply your aquarium's length in cm by its width in cm to find its footprint area in cm².

Mass / Weight Conversion

Note: 1 liter of pure water weighs 1 kg or 1,000 grams.
ounces (oz) 28.34952 grams (g)
pounds (lb) 0.45359237 kilograms (kg)

Light Unit Conversion

Precision is limited to 4 decimal places.
Illuminance

Lux
(lx = 1 lm/m²)
 FootCandle (1 lm/ft²)
Lumen / Square Inch (lm/in²)
Phot (ph)
Watt / m² at a frequency of 540 THz (W/m²)

Luminous intensity

Candela (cd)
 Candle
Violle
Hefner unit

Luminance

Candela / m²

(cd/m²)

(also called "Nit")
 footLambert (fL)
Candela / Square Foot (cd/ft²)
Candela / Square Inch (cd/in²)
Stilb (sb)
Lambert (L)
Skot
Blondel or Apostilb (asb)

Conductivity Conversion

The SI (International System) unit of electrical conductivity is Siemens per meter (S/m), while mho per centimeter (mho/cm) is used in countries employing US customary units. Precision is limited to 4 decimal places.

S / m
mS / cm
µS / cm

As a rough guide, an estimate of
TDS (Total Dissolved Solids)
in saltwater:

ppm TDS

note: mg/L= gr/m³ = ppm
EC (Electrical Conductivity)
CF
mho / cm ( = S / cm )
statmho / m

Liquid Volume Conversion

Spoon and cup volumes are measured level (filled to the rim). One US teaspoon equals nearly 5 milliliters, and one tablespoon is 3 teaspoons (~15 ml). A dessert spoon (less common) equals 2 teaspoons (~10 ml), while a standard cup is often rounded to 250 ml (25 cl).

teaspoons (tsp) 4.928922 milliliters (ml)
tablespoons (tbsp) 14.78676 milliliters (ml)
US cups 23.65882 centiliters (cl)
Be careful to distinguish between US gallons and UK Imperial gallons.
pints US 0.4731765 liters (l)
gallons US 3.785412 liters (l)
gallons GB (imperial) 4.54609 liters (l)
barrel (bbl) (oil) 158.9873 liters (l)

Grams to Milliliters Conversion (and Vice Versa), Useful for Cooking

Enter a value in either of the 2 columns to calculate the equivalent in the other unit. The number in the middle is the conversion factor.

Alcohol 5% 1,01 milliliters (ml)
Check above for approximate conversions using teaspoons, tablespoons, etc.