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18 calculators and counting.
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biotech
Biology
Genetics, cells and living systems.
0 calculators
BiologyPunnett squareSoon
BiologyCell sizeSoon
BiologyDilutionSoon
experiment
Chemistry
Reactions, solutions and the elements.
0 calculators
ChemistryMolar massSoon
ChemistrypHSoon
ChemistryIdeal gas lawSoon
construction
Construction
Materials, dimensions and building work.
0 calculators
ConstructionConcreteSoon
ConstructionRoof pitchSoon
ConstructionPaint coverageSoon
swap_horiz
Conversion
Convert between any pair of units.
0 calculators
ConversionLengthSoon
ConversionWeightSoon
ConversionTemperatureSoon
eco
Ecology
Footprints, energy and the environment.
0 calculators
EcologyCarbon footprintSoon
EcologyFuel costSoon
emoji_objects
Everyday life
The little sums that come up daily.
3 calculators
Open →
Everyday Math Tip
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Shopping Discount
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Shopping Percent Off
Everyday lifeAgeSoon
Everyday lifeTime cardSoon
restaurant
Food
Cooking, nutrition and portions.
0 calculators
FoodCalorieSoon
FoodRecipe scalerSoon
ecg_heart
Health
Body metrics and fitness.
2 calculators
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Health BMI
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Health BMR
HealthBody fatSoon
HealthCalorie needsSoon
HealthIdeal weightSoon
calculate
Math
Percentages, ratios and arithmetic.
2 calculators
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Everyday Math Percentage
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Geometry Pythagorean Theorem
MathFractionSoon
MathRatioSoon
MathAverageSoon
science
Physics
Motion, force and electricity.
3 calculators
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Physics Speed
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Electronics Ohms Law
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Physics Density
PhysicsAccelerationSoon
PhysicsForceSoon
directions_run
Sports
Pace, training and performance.
0 calculators
SportsPaceSoon
SportsOne-rep maxSoon
SportsCalories burnedSoon
bar_chart
Statistics
Averages, spread and probability.
0 calculators
StatisticsMean & SDSoon
StatisticsProbabilitySoon
StatisticsSample sizeSoon
more_horiz
Other
Everything that defies a category.
0 calculators
OtherRandom numberSoon
OtherCountdownSoon
infoAbout

Free, private, and built to stay that way.

Reckon is a growing library of calculators for money, health, math and everyday life. Every page is a fast static file, and every calculation runs entirely in your browser — nothing you type is ever sent to a server.

No accounts, no cookies, no tracking. Favorites, recent calculators and your last inputs are stored only on your device, and you can reset them at any time.