Free Online Biology Calculators

Anatomy & Morphology Calculators help you measure and compare the physical structure and proportions of the human body. Use the arm span to height ratio and body proportions calculators to check classic anthropometric relationships, or estimate bone density with T-Score/Z-Score results similar to a DEXA scan. The cephalic index calculator classifies skull shape, while dental age and organ weight calculators are used in forensic and clinical anatomy. There's also a skeletal muscle mass calculator for body composition analysis.

Animal Gestation & Breeding Calculators help farmers, breeders, and pet owners track pregnancy and incubation timelines across a wide range of species. Estimate due dates with the cow gestation, goat gestation, sheep gestation, and swine gestation calculators for livestock, or use the horse (mare) gestation and llama gestation calculators for larger animals. Poultry and reptile keepers can track hatch dates with the chicken incubation, duck incubation, and reptile egg incubation calculators.

For companion animals, this section also covers cat pregnancy, dog pregnancy, dog heat cycle, guinea pig pregnancy, and rabbit gestation calculators — helping owners plan around breeding cycles and expected litter or hatch dates for nearly any animal in their care.

Biodiversity & Conservation Calculators support the statistical methods ecologists and conservation biologists use to measure and protect species diversity. Compare communities with the Jaccard similarity index, Sorensen's similarity index, and Bray-Curtis dissimilarity calculators, or estimate population size with the capture-recapture (Schnabel) method. The rarefaction curve and species-area curve calculators help standardize biodiversity sampling across different survey efforts.

For conservation planning specifically, this section includes a minimum viable population calculator, population viability analysis calculator, habitat fragmentation index calculator, and an IUCN Red List criteria calculator for assessing a species' extinction risk.

Bioinformatics & Sequence Analysis Calculators bring core computational biology formulas to your DNA, RNA, and protein sequence work. Interpret search results with the BLAST E-value calculator, score how well two sequences match with the sequence alignment score and sequence identity calculators, or run a multiple sequence alignment score for comparing several sequences at once. Molecular biologists can optimize codons for expression, calculate DNA sequence statistics, estimate RNA secondary structure energy, translate mRNA to protein, and check protein hydrophobicity — all without needing specialized bioinformatics software.

Biological Half-Life & Decay Calculators help you work out how quickly a substance or isotope is eliminated from a living system. Use the biological half-life calculator to estimate how long a drug, toxin, or compound stays active in the body, or the radioactive decay calculator to model isotope decay in biological and environmental contexts.

Biostatistics Calculators cover the statistical tests biologists and researchers rely on to analyze experimental and clinical data. Run an ANOVA calculator, chi-square test, correlation coefficient, regression analysis, or t-test to compare groups and relationships in your data, and use the sample size and power analysis calculators to plan a study before you collect it. Confidence interval calculations round out the basics of interpreting results.

For toxicology and clinical research, this section also includes an LD50/LC50 calculator for lethal dose estimation, a dose-response curve calculator, odds ratio and relative risk calculators for epidemiology, a hazard ratio calculator, and a Kaplan-Meier survival calculator for time-to-event data.

Cat Care Calculators help cat owners keep track of their pet's health, growth, and safety at home. Convert your cat's age to human years with the cat age calculator, check a healthy weight with the cat BMI and cat size calculators, or work out daily food needs with the cat calorie calculator. The cat quality of life calculator helps assess comfort and wellbeing for senior or ill cats.

For medication safety, this section also includes dosage calculators for Benadryl, Cephalexin, Metacam, and fish oil, plus a cat chocolate toxicity calculator to quickly check whether an accidental snack is a medical emergency.

Cell Biology & Microbiology Calculators cover the core lab formulas used to grow, count, and analyze cells and microorganisms. Estimate bacterial growth with the bacterial growth curve, generation time, and Monod growth kinetics calculators, or count cells with the hemocytometer cell count, viable cell count, and colony forming units (CFU) calculators. Convert OD600 readings to cell number, calculate cell doubling time, and check cell viability and plating efficiency for culture work.

This section also supports antimicrobial testing with the antibiotic zone of inhibition and minimum inhibitory concentration (MIC) calculators, dilution work with the cell dilution (C1V1=C2V2) and log reduction calculators, and specialized lab tasks like centrifugation RCF/RPM conversion, MOI (multiplicity of infection), mitotic index, osmolarity, and cell passage number tracking.

Cellular Respiration & Metabolism Calculators break down the biochemistry of how cells convert food into usable energy. Calculate ATP yield, work through glycolysis and the Krebs cycle step by step, or estimate electron transport chain output for a full cellular respiration breakdown. The fermentation calculator covers anaerobic energy pathways, while the respiratory quotient (RQ) calculator relates gas exchange to metabolic fuel source.

Rounding out this section are a metabolic rate calculator for estimating energy expenditure and a calorimetry calculator for measuring the heat released by biological reactions.

Dog Care Calculators help dog owners manage their pet's nutrition, growth, and medication safely. Check a healthy weight with the dog BMI and dog size calculators, estimate food needs with the dog food/calorie, dog nutrition, and raw dog food calculators, or track daily water intake with the dog water intake calculator. Fit gear correctly using the dog crate size and dog harness size calculators, and plan ahead with the dog life expectancy and cost of owning a dog calculators.

For medication and safety, this section also includes dosage calculators for Benadryl, Cephalexin, Metacam, Omega-3, and Tramadol, plus toxicity calculators for chocolate, onion, and raisins — along with a dog quality of life calculator for senior or ill dogs.

Ecology & Population Biology Calculators cover the math behind how populations grow, compete, and interact with their environment. Model population change with the logistic growth, exponential population growth, and Lotka-Volterra calculators, or estimate population size in the field with the mark-recapture (Lincoln-Peterson) and abundance estimation calculators. Measure biodiversity with the Shannon diversity index, Simpson's diversity index, species richness, and species evenness calculators.

This section also covers population dynamics in depth: carrying capacity, intrinsic rate of increase (r), net reproductive rate (R0), doubling time, life table, survivorship curve, r and K selection, competition coefficient, and island biogeography calculators. There are also practical ecological footprint, water demand, trophic level energy, population density, and fish mercury calculators for environmental and conservation work.

Environmental Biology Calculators measure how living systems interact with pollution, water quality, and human environmental impact. Calculate your carbon footprint, water footprint, or plastic footprint, or estimate flight emissions and CO2 emissions from everyday activities. Water quality specialists can use the BOD (biochemical oxygen demand), dissolved oxygen, turbidity, and eutrophication risk calculators to assess aquatic ecosystem health.

This section also covers pollution and treatment calculations: bioaccumulation factor, biomagnification, decay rate (organic matter), MLVSS, and wastewater treatment calculators, plus a carrying capacity (human) calculator and an AI water footprint calculator for modern sustainability assessments.

Evolution & Phylogenetics Calculators apply the math of molecular evolution to DNA and protein sequence data. Estimate divergence time with the molecular clock and coalescence time calculators, measure selection pressure with the Ka/Ks ratio and selection coefficient calculators, or calculate phylogenetic distance between species or sequences. The mutation rate, nucleotide substitution rate, and Tajima's D calculators support population genetics research, while the founder effect calculator models genetic drift in small populations.

Forestry & Trees Calculators help foresters, arborists, and landowners measure and value trees. Estimate a tree's age, height, or diameter without cutting it down, calculate basal area for stand density, or work out log volume using the Doyle or Scribner scale for timber sales. The tree carbon sequestration and tree benefits calculators quantify a tree's environmental value.

This section also includes a tree spacing calculator for planting layout, a tree value calculator for appraisal, and a tree leaves calculator for estimating foliage quantity.

Genetics & Heredity Calculators cover classical and population genetics, from a single Punnett square to genome-wide statistics. Work through monohybrid, dihybrid, and trihybrid cross Punnett squares, calculate probability of inheritance, or check codominance, incomplete dominance, and epistasis for non-Mendelian traits. The blood type, Rh factor inheritance, and sex-linked inheritance calculators cover common human genetics questions, while the rabbit color genetics calculator applies the same logic to breeding.

For population genetics, this section also includes the Hardy-Weinberg equilibrium, allele frequency, genotype frequency, gene frequency (multiple alleles), and chi-square goodness of fit calculators, plus inbreeding coefficient, effective population size, F-statistics (Fst, Fis, Fit), linkage disequilibrium, genetic recombination frequency, map distance (centiMorgans), genetic distance, and heritability calculators for more advanced coursework and research.

Human Biology & Physiology Calculators cover the core measurements used to understand how the human body functions. Estimate body fat percentage, body surface area (BSA), ideal body weight, and caloric needs, or check blood alcohol content (BAC) and LDL cholesterol from lab values. Pediatric tools include the child height predictor and growth percentile calculator, while the pregnancy due date and fetal weight calculators support prenatal tracking.

This section also covers cardiovascular and respiratory physiology: mean arterial pressure, QTc (corrected QT interval), respiratory rate, lung capacity, and oxygen consumption calculators, plus an ANC (absolute neutrophil count) calculator used in clinical and hematology contexts.

Immunology & Hematology Calculators support blood and immune system analysis for lab and clinical use. Calculate hematocrit, red blood cell indices, and white blood cell differential from lab values, or estimate reticulocyte production index for anemia workups. The antibody titer and ELISA standard curve calculators support serology testing, while the flow cytometry compensation calculator corrects for spectral overlap in cell analysis.

Public health applications are also covered here: the herd immunity threshold and R0 (basic reproduction number) calculators estimate vaccination coverage and disease spread, alongside a vaccination schedule calculator for tracking immunization timing.

Livestock & Farming Calculators help farmers manage herd size, feed, and production efficiency. Calculate feed conversion ratio (FCR), animal feed ration, and animal weight gain to optimize nutrition, or work out stocking rate and cattle per acre to match herd size to available land. Track productivity with the milk yield and egg production calculators.

This section also includes an animal mortality rate calculator for herd health monitoring and a livestock fence cost calculator for planning pasture infrastructure.

Marine & Aquatic Biology Calculators cover the measurements used to study oceans, lakes, and aquatic life. Estimate fish age using the otolith method, calculate fish length-weight relationship, or track coral growth rate and plankton density in a marine ecosystem. Water quality tools include the water quality index, salinity calculator, ocean acidification pH calculator, and Secchi depth calculator for measuring water clarity.

For aquaculture specifically, this section also includes an aquaculture feed calculator and a tide calculator for planning fieldwork or fishing around tidal cycles.

Molecular Biology & DNA Calculators cover the everyday math of a molecular biology lab, from primer design to cloning. Calculate DNA melting temperature (Tm), GC content, and primer annealing temperature for PCR, or convert between nanograms, picomoles, and molecular weight for DNA and RNA quantification. The qPCR efficiency and qPCR slope to efficiency converter support real-time PCR analysis, while the OD260 to nucleic acid concentration calculator interprets spectrophotometer readings.

For cloning and gene editing work, this section also includes ligation, Gibson assembly, restriction enzyme digest, transformation efficiency, and plasmid copy number calculators, plus a CRISPR guide RNA scoring calculator, codon usage calculator, DNA sequence reverse complement tool, DNA to mRNA converter, and DNA electrophoresis migration calculator.

Neurobiology Calculators apply the core equations of nerve and neuron function to coursework and lab data. Calculate nerve conduction velocity, estimate chronaxie and rheobase for nerve excitability, work out synaptic transmission time, or use the Goldman equation calculator to find resting membrane potential from multiple ion concentrations.

Other Animal Care Calculators cover pet species and habitats that don't fit into a single category, from small mammals to reptiles and birds. Size an enclosure with the aquarium volume, bird cage size, rabbit cage size, rat cage size, reptile enclosure size, and turtle tank size calculators, or estimate age with the bird age, guinea pig age, and hamster age calculators. The horse weight calculator and dry matter calculator (pet food) support feeding and health decisions for larger and smaller pets alike.

This section also includes a fish stocking calculator for aquarium capacity, a crickets chirping thermometer for a fun temperature estimate, and a pet sitter rates calculator for budgeting pet care while you're away.

Pharmacology & Toxicology Calculators cover the core pharmacokinetic formulas used to understand how drugs move through the body. Calculate dosage (mg/kg), drug half-life, clearance rate, and volume of distribution, or work out infusion rate for IV medications. The bioavailability and therapeutic index calculators help assess how effectively a drug reaches its target and how safe its dosing range is, while the drug dilution calculator supports lab and clinical preparation.

Plant Biology & Agriculture Calculators cover plant physiology and farming math side by side. Estimate photosynthesis rate, chlorophyll content, stomatal conductance, transpiration rate, and water potential for plant physiology coursework, or calculate leaf area index (LAI), daily light integral (DLI), and VPD (vapor pressure deficit) for indoor growing and greenhouse management. Seed germination rate and GDU (growing degree units) calculators help predict crop development timing.

For farming and lawn care specifically, this section also includes corn yield, vegetable yield, plant population, plant spacing, and bulb spacing calculators, plus fertilizer, water-soluble fertilizer, irrigation water, and compost calculators. Homeowners can use the soil calculator, potting soil calculator, mulch calculator, sod calculator, grass seed calculator, lawn mowing cost calculator, and acres per hour calculator, while larger operations can size a grain bin volume or run a grain conversion and CO2 grow room calculation.

Protein & Biochemistry Calculators cover enzyme kinetics and protein analysis for biochemistry coursework and lab work. Calculate Michaelis constant (Km) and run a full Michaelis-Menten calculator, or plot enzyme kinetics data with the Lineweaver-Burk, Eadie-Hofstee, and Hanes-Woolf plot calculators. Analyze enzyme inhibition with the competitive, noncompetitive, and uncompetitive inhibition calculators, and calculate turnover number (kcat) and specific activity for enzyme activity studies.

For protein quantification, this section also includes the Bradford assay, BCA assay, extinction coefficient, and protein concentration calculators, plus isoelectric point (pI), amino acid molecular weight, peptide properties, and SDS-PAGE molecular weight estimator tools. Thermodynamics (Gibbs free energy), activation energy (Arrhenius), Q10 temperature coefficient, and Western blot antibody dilution calculators round out the biochemistry toolkit.

Renewable Energy & Biology Calculators cover the biological side of clean energy production. Estimate biofuel yield, biogas production, and biomass energy output from organic material, or calculate the ideal composting carbon-to-nitrogen ratio for efficient breakdown. There's also a solar panel size calculator for pairing renewable energy generation with biological or agricultural operations.

Solution & Lab Preparation Calculators cover the dilution and buffer math every biology and chemistry lab relies on. Use the dilution calculator (C1V1=C2V2) and dilution factor calculator for everyday dilutions, or the bleach dilution and ethanol dilution calculators for specific lab reagents. Prepare buffers accurately with the buffer recipe, Henderson-Hasselbalch, and pKa calculators, and check solution strength with the normality, percent solution, and PPM/PPB concentration calculators.

This section also includes a stock solution calculator, mass/volume solution calculator, reconstitution calculator, solution mixtures calculator, media preparation calculator, and pH titration curve calculator — covering everything from a quick reagent prep to a full titration curve.