Free Science & Astronomy Calculators
These calculators are for amateur astronomers, lab workers and students. Compare eyepieces, convert sky coordinates, estimate the meteors you will see or work out a dilution. Everything runs in your browser and nothing is uploaded.
Featured Science & Astronomy tools
- Telescope Eyepiece CalculatorCompares up to 4 eyepieces on magnification, exit pupil and true field of view.
- Meteor Shower Observed Rate CalculatorCorrects a published ZHR for radiant altitude, light pollution and blocked sky.
- Solution Dilution CalculatorSolves C1V1 = C2V2 and writes out the steps in plain English.
- PCR Primer Tm CalculatorUses nearest-neighbor thermodynamics with salt and DMSO corrections.
Astronomy & Stargazing
4 toolsEquipment, coordinates, sky brightness and meteor showers.
- Amateur Astronomers
Telescope Eyepiece Calculator
Compare up to 4 eyepieces for magnification, exit pupil, true field of view, and suitability for planets, moon, or deep sky.
- Amateur Astronomers
RA/Dec to Alt/Az Converter
Enter right ascension, declination, observer location, and date/time to get altitude, azimuth, and rise/set times.
- Amateur Astronomers
Light Pollution & Stargazing Calculator
Count visible stars to estimate naked eye limiting magnitude and stargazing conditions.
- Stargazers
Meteor Shower Observed Rate Calculator
Turn a published ZHR into the meteors per hour you will really see, corrected for radiant altitude, light pollution and blocked sky, with an hour-by-hour plan for the night and the moon worked out for you.
Lab & Environment
4 toolsPrimer melting temperatures, dilutions, cryogenic storage and air quality readings.
- Molecular Biology
PCR Primer Tm Calculator
Nearest-neighbor thermodynamics (SantaLucia 1998), Wallace rule, salt correction, DMSO adjustment. GC%, hairpin detection, dimer risk, primer pair analysis.
- Lab Techs / Photographers
Solution Dilution Calculator
Enter stock and target concentration to get exact volumes with plain-English step-by-step instructions. %, g/L, mol/L, ppm.
- Cryo Storage Labs
Liquid Nitrogen Dewar Hold Time Calculator
Turn a dewar's capacity and published static evaporation rate into days of liquid left, a refill-by date, the litres needed to top up, and an oxygen displacement check for the room it sits in.
- Wildfire Smoke / Air Quality Watchers
AQI Health Advice Calculator
Enter an air quality index reading and a sensitivity profile to get plain-language activity notes. It is not medical advice.
Which tool do I need?
- Compare telescope eyepiecesTelescope Eyepiece Calculator
- Find where an object is in your sky right nowRA/Dec to Alt/Az Converter
- Estimate how dark your sky isLight Pollution & Stargazing Calculator
- Predict how many meteors you will seeMeteor Shower Observed Rate Calculator
- Work out primer melting temperaturesPCR Primer Tm Calculator
- Prepare a dilution from a stock solutionSolution Dilution Calculator
- Plan a liquid nitrogen dewar refillLiquid Nitrogen Dewar Hold Time Calculator
- Read an air quality index in plain languageAQI Health Advice Calculator
Science & Astronomy FAQ
How do I compare telescope eyepieces?
Enter your telescope and up to four eyepieces into the eyepiece calculator. It compares magnification, exit pupil and true field of view and rates each for planets, the moon or deep sky.
How do I convert RA and Dec to altitude and azimuth?
Enter right ascension, declination, your location and the date and time in the RA/Dec converter. It returns altitude and azimuth and gives rise and set times.
What is the Bortle scale calculator based on?
It uses the Little Dipper method. You count the visible stars and the tool estimates the naked-eye limiting magnitude and stargazing conditions.
Why do I see fewer meteors than the published ZHR?
The ZHR is an idealised rate. The meteor shower calculator corrects it for radiant altitude, light pollution and blocked sky, and gives an hour-by-hour plan for the night.
How do I do a dilution calculation?
Enter the stock and target concentration in the dilution calculator. It solves C1V1 = C2V2, returns the volumes and writes step-by-step instructions, for %, g/L, mol/L and ppm.
Does the air quality tool give medical advice?
No. It turns an air quality index reading and a sensitivity profile into plain-language activity notes. Speak to a healthcare provider about your own health.
Related categories
Last updated: September 30, 2026