Wh to kWh (Energy)
Energy conversion for batteries, power stations and solar systems.
Science
Science converters
Science and physics converters: angles (degrees and radians), temperature scales (Celsius and Kelvin), frequency (Hz and kHz), energy (Wh and kWh), density, time (milliseconds to seconds) and pressure. Useful for physics, programming and lab work.
Last updated: May 2026
Tools in this section
Density Converter
Convert g/cm³ to kg/m³ for materials and filaments.
Degrees to Radians
Essential conversion for mathematics, physics, and programming.
Milliseconds to Seconds
Convert milliseconds for programming, timing, and performance measurement.
Seconds to Minutes
Convert seconds to minutes for video, audio, and exercise timing.
Kelvin to Celsius
Convert Kelvin back to the everyday Celsius scale.
Wavelength to frequency
Optics and physics basics in one quick tool.
Pressure to depth water
Simple diving and pressure-intuition calculator.
Hz to kHz to MHz to GHz
Complete frequency converter for all ranges.
Physics and science units explained
Science converters exist because the units used in textbooks, lab equipment and programming do not always match. The three gaps that come up most often are angle measurement (degrees versus radians), temperature (Celsius versus Kelvin), and signal frequency (Hz to kHz to GHz).
Radians are the natural unit for angles in mathematics and most programming languages. One full rotation is 2 pi radians (6.2832), which is where trigonometric functions like sin() and cos() expect their input. When a hardware specification or a sensor gives an angle in degrees, multiply by pi/180 before passing it to a function. That is what the degrees to radians converter does.
Kelvin is Celsius shifted upward by 273.15 so that zero means no thermal energy at all. Every gas law that involves temperature (Boyle, Charles, Gay-Lussac) requires Kelvin, because the ratio of two temperatures is only physically meaningful when zero is absolute. Room temperature of 20 C is 293.15 K.
Wavelength and frequency are tied together by wave speed. For electromagnetic waves in a vacuum the formula is f = c / lambda, where c is 299,792,458 m/s and lambda is the wavelength in metres. Double the frequency and the wavelength halves exactly. The table below gives reference ranges for common parts of the spectrum.
| Part of spectrum | Wavelength range | Frequency range | Common application |
|---|---|---|---|
| AM radio | 100 m to 1000 m | 300 kHz to 3 MHz | Broadcast audio |
| FM radio / Wi-Fi 2.4 GHz | 0.1 m to 1 m | 300 MHz to 3 GHz | Audio, wireless LAN |
| Visible light (red) | 625 nm to 740 nm | 400 THz to 480 THz | Laser pointers, LEDs |
| Visible light (violet) | 380 nm to 450 nm | 670 THz to 790 THz | Near-UV border, fluorescence |
| Infrared (near) | 780 nm to 2500 nm | 120 THz to 380 THz | Remote controls, night vision |
Where science units appear in practice
Density conversions (g/cm3 to kg/m3) come up in materials work and 3D printing, where filament datasheets list density in g/cm3 but some CAD or slicer tools expect kg/m3. Multiply by 1000: water is 1 g/cm3 = 1000 kg/m3.
Energy conversions (Wh to kWh) matter for battery and solar sizing. A 10,000 mAh phone power bank at 3.7 V holds about 37 Wh, or 0.037 kWh. A 100 kWh EV battery holds 2700 times as much. The Wh to kWh converter handles both directions and the large range of values encountered in electronics and energy storage.
Time conversions (milliseconds to seconds, seconds to minutes) appear in performance profiling, audio editing and sensor data. A 16.67 ms frame budget is the limit for a 60 fps animation loop. An audio sample at 44,100 Hz has one sample every 0.0227 ms. These small numbers come up constantly in embedded systems and web performance work.
Cross-links
Frequently Asked Questions
How do I convert degrees to radians?
Multiply degrees by pi divided by 180 (about 0.01745). So 180 degrees is pi radians, roughly 3.1416, and 90 degrees is about 1.5708. To go back, multiply radians by 180 divided by pi.
Why use Kelvin instead of Celsius?
Kelvin starts at absolute zero, so it never goes negative and is required for gas laws and thermodynamics. Convert with K = degrees C + 273.15, so 25 C is 298.15 K. The size of one degree is the same in both scales.
How are wavelength and frequency related?
They are inversely related: frequency equals the wave speed divided by wavelength. For light, speed is about 300 million metres per second, so a longer wavelength means a lower frequency. The wavelength to frequency tool does the arithmetic.
What is the difference between g/cm³ and kg/m³?
They measure the same thing at different scales: 1 g/cm³ equals 1000 kg/m³. Water is 1 g/cm³, which is 1000 kg/m³. Multiply g/cm³ by 1000 to get kg/m³.
How many milliseconds are in a second?
There are 1000 milliseconds in a second, so 1 ms is 0.001 s. Milliseconds are common in programming, performance timing and audio, where small fractions of a second matter.
What is the relationship between frequency and wavelength for visible light?
Use f = c / lambda where c is 299,792,458 m/s. Red light at 700 nm has a frequency of about 428 THz; violet light at 400 nm has about 750 THz. The wavelength to frequency tool does the division for any input wavelength.
When do I need Kelvin instead of Celsius?
Whenever a formula multiplies or divides temperatures rather than adding or subtracting them. Gas laws (pressure, volume, temperature relationships), blackbody radiation and absolute efficiency calculations all require Kelvin. Simple offsets like weather or cooking stay in Celsius.
Why do radians matter in programming?
Most maths libraries (JavaScript Math, Python math, C math.h) pass angles in radians to sin, cos and tan. If you supply degrees the function returns a wrong result silently. Convert degrees to radians by multiplying by Math.PI / 180 before the call.