Science tools
Calculators and simulators that show their working. Everything runs in your browser, nothing to sign up for, and each tool comes with a plain-language guide to the science behind it.
Curiosity science
Plug in your own numbers and find out something about the universe, and about you.
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Age on other planets calculator How old you are on Mercury, Mars, Jupiter and Neptune, and when your next birthday lands. -
How far have you travelled through space? Your lifetime distance around the Sun, around the galaxy and through the cosmos. -
Your birthday star The bright star whose light set off the year you were born. -
Light travel time calculator How long light takes from the Moon, the Sun, Pluto, the nearest star or Andromeda. -
How long to get to the Moon, Mars or Pluto? Travel time by car, airliner, rocket or probe to anywhere in the solar system. -
Lightning distance calculator Count the seconds from flash to thunder and see how far away the strike was. -
Weight on other planets What you would weigh on every planet and moon. -
Asteroid impact simulator Pick a size and speed, see the crater and the blast. -
Earthquake energy calculator What each step on the magnitude scale means in energy. -
Black hole size calculator How small anything has to shrink to become a black hole. -
Earth curvature and horizon calculator How far you can see, and how much of a distant object hides behind the curve. -
Fall through the Earth Drop through a tunnel to the other side: how long does it take? -
Terminal velocity calculator How fast a skydiver, a raindrop or a cat really falls. -
Boiling point at altitude Why pasta takes longer in the mountains. -
Why is the sky blue? Sunset simulator Move the Sun and watch the sky change colour. -
What if we replace the Sun? Swap in another star and see what happens to Earth. -
Zoom out to the edge of the universe From an astronaut to the cosmic background, at true scale. -
Heat index and wind chill calculator How hot or cold it really feels, from temperature, humidity and wind, with the danger bands. -
Dew point and humidity calculator Dew point from temperature and relative humidity, and why muggy days feel muggy. -
Carbon dating calculator Age from the carbon-14 left in a sample, and how far back the method can reach.
Space and stargazing
Telescopes, the Moon, the planets and the night sky, worked out for where you are.
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Moon phase on any date What the Moon looked like on your birthday, or on any date from 1900 to 2100. -
Day length calculator Hours of daylight anywhere on Earth on any date, and why it changes. -
Telescope magnification calculator Magnification, field of view and the faintest star your telescope and eyepiece can show. -
Star trail exposure calculator (500 and NPF rules) The longest shutter time before stars streak, for your camera and lens. -
Moon phases simulator Why the Moon changes shape through the month. -
Eclipse simulator Line up the Sun, Moon and Earth. -
Planet and star size comparison Line the planets and stars up side by side. -
How long does it take to get to Mars? Plan a Hohmann transfer and a launch window. -
Star colour and temperature Why hot stars are blue and cool stars are red. -
Orbits and Kepler’s laws Change the orbit and watch the planet speed up and slow down. -
Rocket equation simulator Why reaching orbit takes so much fuel. -
Time dilation calculator How much slower clocks run near a black hole or in orbit. -
Escape velocity calculator Escape and orbital speed from any planet, moon or star, with the launch drawn to scale.
Students and teachers
Physics calculators that show the working, for homework, labs and lessons.
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SUVAT calculator (kinematics equations) Enter any three of s, u, v, a, t and get the other two, with every step shown. -
Free fall calculator Fall time and impact speed from any height, with and without air. -
Kinetic and potential energy calculator Watch energy swap between height and speed on a drop or a ramp. -
Inclined plane calculator Forces, friction and acceleration of a block on a slope, drawn to scale. -
Gravitational force calculator Newton’s law of gravitation between any two bodies, from apples to planets. -
Wavelength and frequency calculator Convert wavelength, frequency and photon energy for light, radio and sound. -
Scientific notation converter Standard form, engineering notation and SI prefixes, both ways. -
Significant figures calculator Count sig figs, round to any number of them, and do sums with the right precision. -
Percent error calculator Percent error, percent difference and what counts as a good result in a lab. -
Projectile motion simulator Which launch angle goes farthest? -
Pendulum simulator The period formula, tested. -
Snell’s law simulator How light bends, reflects and gets trapped. -
Lens ray diagram Draw the image for any object distance. -
Double slit experiment Waves, particles and watching the slits. -
Half-life calculator and decay simulator Watch atoms decay and the half-life appear. -
Doppler effect simulator Why a siren drops pitch as it passes. -
Collisions and momentum Elastic and sticky collisions on an air track. -
Buoyancy simulator Why some things float and how deep they sit. -
Electric field simulator Place charges and see the field lines. -
Series and parallel circuits Build a circuit and see the current split. -
Hooke’s law calculator (spring constant) Spring constant, stretch, force and stored energy, with springs in series and parallel. -
Centripetal force calculator Force and acceleration for anything going round: a car on a bend, a bucket, a satellite. -
Speed of sound calculator Speed of sound in air at any temperature, and in water, steel and other materials. -
Speed, distance and time calculator Solve for speed, distance or time with any units, plus average speed over several legs. -
Work and power calculator Work, power and energy for lifting, climbing stairs or pushing, in joules, watts and horsepower.
Chemistry and lab
Molar mass, gas laws, heat and the numbers every lab report needs.
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Molar mass calculator Type a formula like Ca(OH)2 and get the molar mass with each element’s share. -
Ideal gas law calculator Solve PV = nRT for any unknown and watch the piston move. -
Specific heat calculator Energy to heat, melt or boil anything, with the heating curve of water. -
Density calculator Density, mass or volume for any object, with a float or sink check against water.
Electronics and batteries
Bench calculators for makers: resistors, LEDs, batteries, timers and power.
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LED resistor calculator The right resistor for any LED and supply. -
Resistor colour code calculator Read or pick the bands for any resistor. -
Ohm’s law calculator Voltage, current, resistance and power. -
Voltage divider calculator Pick two resistors for the voltage you need. -
Voltage drop calculator How much voltage a long wire wastes. -
Battery life calculator How long a battery runs your project. -
555 timer calculator Frequency and duty cycle in astable mode. -
PWM duty cycle simulator How a fast switch dims an LED. -
Capacitor charging calculator RC time constant, charge and discharge. -
Transistor switch calculator The base resistor that drives a load fully on. -
Logic gates simulator AND, OR, NOT and friends with truth tables. -
Power bank calculator: how many phone charges? Real phone charges from any power bank, after voltage conversion and losses. -
Charging time calculator for phones and laptops How long a phone, tablet or laptop takes on a 5 W to 140 W charger, and why the last 20% is slow. -
Battery pack calculator (series and parallel cells) Build a pack from 18650, 21700 or LiFePO4 cells: voltage, capacity, energy and current. -
mAh to Wh converter Convert mAh, Ah and Wh at any voltage, and check the 100 Wh airline limit. -
Capacitor code calculator (104 = 100 nF) Decode or make the three-digit code on ceramic and film capacitors, with tolerance and voltage letters. -
SMD resistor code calculator Decode 3-digit, 4-digit and EIA-96 codes on surface-mount resistors. -
LM317 resistor calculator Pick R1 and R2 for any output voltage, with dropout and heat checked. -
Op-amp gain calculator Inverting and non-inverting amplifier gain, resistor values and the bandwidth you are left with. -
Decibel calculator (dB, dBm, ratios) Convert power and voltage ratios to dB, dBm to watts, and add sound levels correctly. -
PCB trace width calculator Trace width for any current and copper weight (IPC-2221), with temperature rise and voltage drop. -
Wire size calculator for 12 V and 24 V The AWG or mm² wire for a 12 V or 24 V run, from current, length and the voltage drop you accept. -
RC filter calculator Cutoff frequency for a low-pass or high-pass RC filter, with a live frequency response plot. -
Antenna length calculator (quarter wave and dipole) Quarter-wave and half-wave dipole lengths for any frequency, from 433 MHz modules to FM and ham bands. -
Stepper driver Vref calculator (A4988, DRV8825, TMC2209) The Vref to set on your stepper driver for your motor’s current, for 3D printers and CNC. -
Crystal load capacitor calculator The two capacitors your crystal needs, from its load capacitance and the board’s stray capacitance. -
Heatsink calculator Will your regulator or MOSFET overheat? Junction temperature and the heatsink you need. -
Buck converter calculator Duty cycle, inductor, ripple and output capacitor for a step-down converter.
Home energy and money
What your appliances, solar panels and EV really cost to run.
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Electricity cost calculator What any appliance costs to run. -
Inverter battery backup calculator How long your inverter lasts in a power cut. -
EV charging time calculator Hours to charge any EV on any charger. -
Solar panel angle calculator The best tilt for your latitude and season. -
AC running cost calculator What your air conditioner costs per hour, day and month, by tonnage, star rating and tariff. -
Rooftop solar size and payback calculator How many kW of panels your bill needs, the roof area, and how many years until it pays back. -
EV vs petrol running cost calculator Cost per km and per year of an electric car or scooter against petrol, with your prices. -
LED bulb savings calculator Money and energy saved by swapping old bulbs and tubes for LEDs, and how fast they pay back. -
Water heater (geyser) cost calculator Energy and cost to heat water for a shower or bath, and how long a geyser takes to heat up.
Everyday utilities
Quick, private tools that run in your browser: QR codes, converters and timers.
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QR code generator Make a QR code for a link, text, Wi-Fi or contact card. Free, private, no sign-up. -
Science unit converter Length, mass, energy, pressure, temperature and more, with the conversion factor shown. -
Random group generator for classes Paste a class list and split it into fair random groups or teams, private and in your browser. -
Online tone generator Play any frequency from 20 Hz to 20 kHz, sweep it, and find the highest pitch you can hear.
No tool matches that yet. Try a shorter word.
Coming soon
- Echo distance calculator