Science
1,125 science calculators for chemistry, physics, biology, astronomy and the Earth sciences. Each one states the relation it uses and the units it expects, so class problems, lab work and quick checks come out right, free in your browser.
Dog heat cycle calculator
If your dog's last heat began on 15 January 2026 and her cycle is six months, the next one is expected around 15 July 2026, with a watch window from 8 to 22…
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Dog raisin toxicity calculator
A 10 kg dog that eats 10 raisins has taken in 5 g, or 0.5 g per kilogram, which falls in the low educational band.
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Fish oil dosage for cats
Turn your cat's weight into a daily omega-3 amount: a 5 kg cat at a 40 mg per kg target needs 200 mg of EPA plus DHA, the figure to compare with the label on…
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Guinea pig age calculator
Find out how old your cavy is in human terms: a 2-year-old guinea pig is about 26.7 human years, because its age is scaled by an 80-year human life against a…
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How big will my cat get
Find out how big your kitten will be: a 12-week-old kitten weighing 1 kg is about a quarter of its adult size and projects to 4 kg, since most cats finish…
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Omega-3 for dogs
A 20 kg dog on a 50 mg per kilogram target needs 1000 mg of combined EPA and DHA a day, a figure you can match to a capsule or pump label.
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Plant population calculator
Know your stand before you order trays: a 1000 square-metre bed at 0.5 metre square spacing holds 4000 plants, 4 per square metre.
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Protein concentration calculator
Read protein concentration straight off your standard curve: an absorbance of 0.85 with a slope of 0.4 and an intercept of 0.05 gives 2 mg/mL.
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qPCR efficiency calculator
Check a qPCR assay from its standard curve: a slope of −3.32 means an efficiency just over 100%, an amplification factor of 2.000805254556 per cycle, so the…
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Rabbit gestation calculator
A doe mated on 1 March 2026 is due to kindle on 1 April 2026, 31 days later, the textbook average for domestic rabbits.
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Sod calculator
A 50 by 20 lawn with 120 of patio and beds leaves 880 to cover, which is 88 rolls on 2 pallets: the calculator subtracts every obstacle before counting turf.
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Cost of owning a dog calculator
Over a 12-year life, a dog's food, vet care and supplies are paid 12 times while the purchase or adoption fee is paid once: the calculator adds it all up and…
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Tree diameter calculator
A tape reading of 100 cm around the trunk gives a diameter at breast height of about 31.83 cm: the calculator divides the girth by pi and returns the diameter…
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Tree value calculator
A condition rating of 0.8 keeps 80 % of a tree's basic value: the calculator multiplies trunk cross-sectional area by the species value factor and the condition…
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Vegetable yield calculator
A 12 square metre tomato bed at 4.5 kilograms per square metre should give about 54 kilograms of fruit: the calculator multiplies planted area by the yield rate…
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Wastewater BOD removal efficiency calculator
Influent BOD of 250 mg/L and effluent of 25 mg/L mean 90 % removal: the calculator compares what enters and leaves the plant and shows the concentration removed…
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AI water footprint calculator
A thousand AI queries at half a liter each consume 500 liters of freshwater, or 0.5 cubic metres: enter your own query count and the intensity from your source…
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Carrying capacity calculator
One thousand tonnes of winter forage at four tonnes per animal supports 250 animals: divide any limiting resource by the use per individual to get the…
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COVID lockdown pollution calculator
A city that went from ten million to four million vehicle-kilometres at 0.32 g of NOx per kilometre avoided 1,920 kg of NOx: turn a traffic drop into grams…
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Eco-friendly bags
Fifty-two plastic bags at 1.6 units each total 83.2, fifty-two paper bags at 5.5 total 286 and one reusable tote at 40 totals 40, so the tote ranks first…
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Global plastic policy calculator
A country generating ten million tonnes of plastic a year that adopts a 25 percent cut removes 2,500,000 tonnes and is left with 7,500,000: turn a policy…
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Kaya identity calculator
One hundred people at 50 of GDP each, an energy intensity of 2 and a carbon intensity of 0.5 give emissions of 5,000: see which of the four Kaya drivers moves…
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Meat carbon footprint calculator
Eating 1.5 kg of beef a week at 27 kg of CO2e per kilogram adds up to 2,106 kg of CO2e a year: enter your own weekly amount and factor to compare beef, pork or…
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Passive house heating savings
A 150 m² home in a cold climate with average insulation saves 17,568 kWh of heating a year as a Passive House.
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Reduce your plastic
Swapping 7 bottles, 4 bags, 3 straws, 2 cups, 1 takeaway container and 5 utensils a week for reusables avoids 165.76 g of plastic a week, more than 8 kg a year.
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Tap water calculator
A kitchen tap at 8 liters per minute running 15 minutes a day uses 120 liters daily and 43,800 liters a year.
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Tree benefits calculator
Ten street trees at 22 kg of CO2 and 118 kg of oxygen each per year absorb 220 kg of CO2 and release 1180 kg of oxygen.
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Wind turbine energy calculator
An 80 m rotor in a steady 10 m/s wind with a power coefficient of 0.4 delivers over a million watts and more than ten million kWh a year.
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Allele frequency calculator
Count genotypes, get allele frequencies: 320 AA, 160 Aa and 20 aa individuals hold 1000 gene copies, so p is 0.8 and q is 0.2, adding to one.
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Bacteria growth calculator
Find how many bacteria you will have: 100 cells that double every 20 minutes become 800 after 60 minutes, three doublings and a growth factor of 8.
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Bulb spacing calculator
Know how many bulbs to buy before you dig: a bed 120 by 60 with a gap of 15 takes 9 bulbs per row in 5 rows, 45 in total, evenly spaced at 15.
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Cat calorie calculator
Work out a cat's daily energy need: resting energy is 70 times weight in kilograms to the power 0.75, and a neutered indoor adult of 4.5 kg then gets a…
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Cat calorie calculator
Get a daily calorie target for your cat: a 3-year-old, 4.5 kg cat with a sedentary routine needs about 260 kcal a day, from a resting need of 216.28 times 1.2.
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Cell doubling time calculator
1,000 cells that reach 8,000 in 24 hours have doubled three times, so each generation took 8 hours.
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Cephalexin for dogs dosage
A 10 kg dog prescribed cephalexin at 22 mg/kg needs 220 mg per dose, which is 0.88 of a 250 mg tablet.
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Cricket chirp thermometer
Count a cricket's chirps for one minute: 120 chirps means about 70 °F, following Dolbear's law from 1897, with the Celsius value alongside.
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DNA concentration calculator
An A260 reading of 0.50 on a ten-fold dilution means 250 ng/µL of double-stranded DNA in your stock: absorbance times 50 times the dilution.
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Dog BMI calculator
A 30 kg dog with a 75 cm chest and a 70 cm body length falls in the ideal category, judged from weight and tape measurements instead of a human BMI chart.
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Dog food calculator
A 20 kg four-year-old dog eating a 350 kcal-per-cup kibble needs about 3.03 cups, or 314.7 g, a day, based on resting energy and a life-stage factor.
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Dog Metacam calculator
A 10 kg dog prescribed Metacam (meloxicam) at 0.1 mg/kg needs 1 mg per dose. Enter the scale weight and the rate your veterinarian wrote to get a repeatable…
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Dog pregnancy calculator
A bitch mated on 1 March 2026 is due around 3 May 2026, 63 days later, with a whelping window from 28 April to 8 May.
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Dog water intake calculator
A 10 kg dog at rest needs about 600 mL of water a day: 60 mL per kilogram times an activity factor of 1.
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Feed conversion ratio calculator
A broiler flock that eats 3.6 kg of feed and gains 2.4 kg of live weight has an FCR of 1.5: one and a half kilos of feed per kilo of gain.
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Grain bin calculator
Turn bin diameter and grain depth into storage capacity: an 18 ft bin filled to 16 ft is a cylinder with a 9 ft radius, and its cubic feet become bushels at…
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Hamster age calculator
See what life stage your hamster is really in: at 12 months a Syrian hamster is about 42 in human years and already a senior, because hamsters grow up far…
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Horse weight calculator
Get the weight your ration, dewormer dose and trailer limit depend on without a walk-on scale: a 72 in heart girth and 68 in body length give 1068.2182 lb, or…
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Mutation frequency calculator
Turn a colony count into mutants per cell: 50 resistant colonies from 100000000 viable cells plated means one mutant in every 2000000 cells, a figure you can…
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Pet sitter rates calculator
Quote a house sit in one step: a daily rate of 45 for the first pet plus 15 for a second dog, over 5 days, comes to 60 a day and 300 for the stay.
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Pine straw calculator
Order the right number of bales before the truck leaves: 500 square feet of beds at 40 square feet per bale needs 12.5 bales, so you buy 13 and cover 520.
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Plants calculator
Buy the right number of seedlings: a bed of 12 square metres with plants 0.5 metres apart on a square grid holds 48 plants, 4 per square metre, with no soil…
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Potting soil calculator
Buy the right bag of potting mix: a round pot 20 cm across and 18 cm deep holds a little over five and a half litres.
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Punnett square calculator
Cross two parents for one gene and see the whole grid: Aa × Aa gives one AA, two Aa and one aa, a 1:2:1 genotype ratio and a 3:1 dominant-to-recessive phenotype…
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Rabbit cage size calculator
Size a hutch before you buy the wire: three medium rabbits of 2 to 4 kg need at least 9 square feet of floor, 3 each, and the cage must be 14 inches high…
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Rabbit coat color calculator
Plan a mating by color, not by raw genotypes: two AaBbCcDd parents give 256 equally likely combinations, with chestnut in 81 of them (31.640625%) and ruby-eyed…
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Rat cage calculator
Check a cage before you buy it: two pet rats need at least 4 cubic feet, 2 per rat, which at 20 inches high means a floor of 2.4 square feet, about 26 by 13…
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Raw dog food calculator
A 20 kg adult dog fed 2.5% of its body weight needs 500 g of raw food a day, so the portion follows the dog, not a kibble bag.
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Sheep gestation calculator
A ewe bred on January 1, 2026 is due around May 28, 2026: the calculator adds the standard 147-day sheep gestation to the breeding day so you can plan lambing…
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Soil calculator
A bed 8 by 4 feet filled 1 foot deep holds 32 cubic feet of soil, a little more than one cubic yard: the calculator gives the volume in cubic feet, cubic yards…
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Swine gestation calculator
A sow bred on January 1, 2026 is due to farrow around April 25, 2026: the calculator adds the 114-day mean pig gestation, the three months, three weeks and…
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Tramadol for dogs
A 10 kg dog at a prescribed 3 mg/kg needs 30 mg of tramadol per dose: the calculator multiplies body weight by your veterinarian's milligrams-per-kilogram rate…
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