Science: Free Online Calculators and Tools

Scientific units of measurement are standardized and universally accepted ways to quantify physical quantities. They are essential for science, technology, and trade because they ensure consistency, allow for clear communication, and enable reproducible experiments and accurate comparisons of data across the globe.  

Here’s a breakdown of the key aspects:

1. Standardization: Scientific units are defined very precisely based on fundamental physical constants or stable phenomena. 

2. Universality: The goal is to have a single, coherent system used worldwide, especially in scientific research and international collaborations.

3. The International System of Units (SI): This is the modern form of the metric system and the most widely used system of measurement in science and globally (including Italy). It’s built upon seven base units, each representing a fundamental physical quantity:  

    
   • Meter (m): Unit of length.  
      
   • Kilogram (kg): Unit of mass.  
      
   • Second (s): Unit of time.  
      
   • Ampere (A): Unit of electric current.  
      
   • Kelvin (K): Unit of thermodynamic temperature (Celsius, °C, is also commonly used in many contexts and is derived from Kelvin).  
      
   • Mole (mol): Unit of amount of substance (used heavily in chemistry).  
      
   • Candela (cd): Unit of luminous intensity.  
      

4. Derived Units: All other scientific units can be derived from these seven base units through multiplication and division. Examples include:  

    
   • Area: square meter (m²)  
      
   • Volume: cubic meter (m³) (Litres are also commonly used, where 1 L = 0.001 m³)  
      
   • Speed: meter per second (m/s)  
      
   • Force: Newton (N), which is kg⋅m/s²  
      
   • Energy: Joule (J), which is N⋅m or kg⋅m²/s²  
      
   • Power: Watt (W), which is J/s  
      
   • Pressure: Pascal (Pa), which is N/m²  
      
   • Frequency: Hertz (Hz), which is 1/s  
      

5. Prefixes: The SI system uses prefixes to denote multiples and submultiples (powers of 10) of units, making it convenient to express very large or very small quantities. Examples include:  

    
   • kilo- (k): 1,000 (e.g., kilometer, km = 1000 m)
   • milli- (m): 0.001 (e.g., milligram, mg = 0.001 g)
   • micro- (µ): 0.000001 (e.g., microsecond, µs)
   • nano- (n): 0.000000001 (e.g., nanometer, nm)
   • mega- (M): 1,000,000 (e.g., megawatt, MW)
   • giga- (G): 1,000,000,000 (e.g., gigabyte, GB)

      

To convert Celsius to Kelvin, simply add 273.15 to the temperature in Celsius.

Ohm’s Law describes the relationship between voltage (V), current (I), and resistance (R): V = I × R.

Frequency refers to how often an event repeats per second and is measured in hertz (Hz).

Energy in joules is calculated by multiplying power (watts) by time (seconds).

pH measures the acidity or alkalinity of a solution on a scale from 0 to 14, with 7 being neutral.

These prefixes represent powers of ten to express very large or very small numbers (e.g., 1 km = 1000 m).

Mass is the amount of matter in an object (in kg), while weight is the gravitational force acting on that mass (in newtons).

It’s a tool for converting and comparing radiation units like becquerel, sievert, and gray.

The speed of light in a medium is equal to its speed in vacuum divided by the refractive index of the medium.

Scientific calculators are used for complex mathematical operations such as trigonometry, logarithms, exponents, and scientific notation — essential in science and engineering.

BMI (Body Mass Index) is calculated as weight (kg) divided by height (m) squared: BMI = weight / (height²). It is a health indicator of body fat.

It helps measure the amount of variation or dispersion in a set of values — useful in statistics and scientific data analysis.

The energy of a photon can be calculated using the formula E = h × f, where h is Planck’s constant and f is the frequency.

It converts frequency units like Hz, kHz, MHz, or GHz — useful in physics, telecommunications, and electronics.

Mass is the amount of matter in an object (kg), while weight is the force exerted by gravity on that mass (N).

It allows you to convert between Celsius, Fahrenheit, Kelvin, and Rankine — often needed in scientific experiments and data comparison.

Scientific notation expresses very large or small numbers in the form a × 10^n. It simplifies calculations in science and engineering.

Exponents represent repeated multiplication; roots are the inverse. Both are common in physics, chemistry, and biology formulas.

Length (m, cm, nm), mass (g, kg), time (s), temperature (C, K), energy (J, eV), and pressure (Pa, atm) are frequently converted.