Free Biotechnology & Molecular Biology Calculators
Fast, free scientific calculators for molecular biology, biotechnology, biochemistry, cell culture and laboratory research. Every tool shows its formula, works through real numbers and cites its sources — and every calculation runs locally in your browser.
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Popular calculators
Start with the molarity calculator, the most-used concentration tool at the bench, or browse the full laboratory calculator collection.
- Molarity CalculatorSolve molarity, mass, volume or moles.
- Dilution CalculatorC1V1 = C2V2 stock dilutions.
- DNA Molecular Weight CalculatorMW from length or sequence.
- Primer Tm CalculatorMelting temperature estimates.
- PCR Master Mix CalculatorPer-reaction and total volumes.
- DNA Concentration CalculatorFrom A260 absorbance.
- OD600 CalculatorCell density from optical density.
- Punnett Square CalculatorOffspring ratios and carrier risk.
- Hardy-Weinberg CalculatorAllele frequencies and the equilibrium test.
Browse by category
Tools are organised by the branch of lab science they serve. The laboratory suite, the DNA & RNA, PCR & qPCR, cell culture, protein, molecular cloning, biochemistry, microbiology and genetics hubs are live now.
- LaboratoryMolarity, dilution, stock solutions, percent and ppm.
- DNA & RNAGC content, primer Tm, molecular weight and A260 concentration.
- PCR & qPCRPrimer Tm, master mix setup and qPCR standard-curve efficiency.
- ProteinMolecular weight, isoelectric point and A280 concentration.
- Molecular CloningRestriction enzyme site finding, plasmid molecular weight, ligation ratio and transformation efficiency.
- BiochemistryBeer-Lambert, enzyme kinetics and buffers.
- Cell CultureCounting, viability, seeding density, doubling time and CFU plate counts.
- MicrobiologyOD600 cell density, CFU plate counts and growth kinetics.
- GeneticsPunnett square crosses, carrier risk across children, X-linked and linked-gene ratios, and Hardy-Weinberg allele frequencies with the equilibrium test.
Browse by workflow
Calculators are grouped by the task you are doing, not the alphabet. Each workflow chains the tools you reach for in sequence — concentration first, then dilution, then reaction setup.
Prepare a Solution
Prepare DNA / RNA
- DNA MW
- DNA Concentration
- DNA Molarity
Set Up PCR
Culture Cells
Characterize a Protein
Analyze Results
Predict Inheritance
Why you can rely on these numbers
A calculator is only as good as the method behind it. BioSyn tools are built for the bench, where a wrong concentration wastes a week of work.
Formula shown, not hidden
Every result page states the equation, defines each variable and walks a worked example with real numbers.
Sources & review date
Each tool cites the references behind its method and carries a last-reviewed date, so you can check the science.
Runs locally in your browser
Calculations happen on your device. Nothing is uploaded, stored or sent to a server, and there is no login.
Learn the method
Every calculator is paired with a guide that explains the why behind the numbers — the formula, the assumptions and the mistakes to avoid. Read what is molarity or the step-by-step how to calculate molarity.
- The C1V1 = C2V2 EquationC1V1 = C2V2 explained: what each term means, all four rearrangements, the unit-matching rule, and how 10x stock maps to 1:10 and 1:100 dilutions.
- How to Calculate a DilutionCalculate any dilution with C1V1 = C2V2: find the stock volume, diluent volume, dilution factor or final concentration, with ratio and percentage tables.
- How to Calculate Cell Viability with Trypan BlueCalculate cell viability by hand from trypan blue counts: viability % = live/total × 100, viable cell density, the ~90% threshold and the read window.
- How to Calculate CFU/mL from Plate CountsCalculate CFU/mL by hand from colony counts: the dilution factor, plated volume, the 25–250 countable range, plate selection and why a CFU is not one cell.
- How to Calculate Delta Delta Ct (2^-ΔΔCt)Work the Livak 2^-ΔΔCt method by hand: normalise to a reference gene, subtract the control, convert to fold change, and check efficiency and error first.
- How to Calculate DNA Concentration from A260Convert an A260 reading to DNA concentration: the 50/33/40 factors, where they come from, dilution factor and path length, and ug/mL to nM by hand.
- How to Calculate DNA Molecular WeightCalculate the molecular weight of a DNA oligo by hand: free-acid residue masses, the terminal correction, 5'-OH vs 5'-phosphate, and ug-to-nmol.
- How to Calculate Population Doubling TimeDerive doubling time by hand from two cell counts: Td = t·ln2/ln(Nt/N0), the log₂ form, specific growth rate, PDL vs passage number and the log-phase rule.
- How to Calculate GC ContentCalculate the GC content of a DNA or RNA sequence: GC% = (G + C) / length × 100, with worked examples, IUPAC degenerate-base rules and why GC% matters.
- How to Calculate a Ligation Ratio (Insert:Vector)Calculate the insert:vector molar ratio for a ligation: convert fragment sizes and vector mass into the ng of insert to add, or reverse from masses used.
- How to Calculate Michaelis–Menten KineticsWork the Michaelis-Menten equation by hand: solve v, Vmax, Km or [S], get kcat and efficiency, and read an inhibition pattern from apparent constants.
- How to Calculate Molar MassCalculate molar mass from any formula: sum atomic masses, handle hydrates, and convert grams to moles. Worked examples for H2O, NaCl and glucose.
- How to Calculate MolarityCalculate molarity in three steps: convert mass to moles, volume to litres, then divide. Worked examples for NaCl, glucose and a 10 mM reagent.
- How to Calculate Plasmid Molecular WeightCalculate plasmid molecular weight from length in bp on the 660 g/mol·bp convention, then convert to pmol/µg, molarity, molecules and copy number.
- How to Calculate Primer TmCalculate primer melting temperature (Tm) two ways: the quick Wallace rule and the SantaLucia 1998 nearest-neighbour method, with a worked example.
- How to Calculate Protein Isoelectric Point (pI)How to calculate a protein's isoelectric point (pI) from sequence: ionizable groups, pKa values, the net-charge sum and why you must iterate.
- How to Calculate Protein Molecular WeightSum the residue masses and add one water to get a protein's molecular weight in Da and kDa — worked example, average vs monoisotopic, and sources.
- How to Calculate qPCR EfficiencyCalculate qPCR amplification efficiency from a standard curve by hand: regress Cq on log10 concentration, why slope -3.32 is 100%, and the 90-110% window.
- How to Calculate Cell Seeding DensityWork out seeding density by hand: target density to cells per well, the growth-area conversion, and C1V1 = C2V2 to get the volume of stock to pipette.
- How to Calculate Transformation Efficiency (CFU/µg)Calculate transformation efficiency in CFU/µg: apply the plated-volume dilution factor, convert DNA mass to µg, and read it against the expected range.
- How to Choose a PCR Annealing TemperaturePick a PCR annealing temperature from primer Tm: the empirical Tm−5 start, the Rychlik Ta-optimum formula, gradient windows and mismatched primer pairs.
- How to Convert OD600 to Cell DensityTurn an OD600 reading into cells/mL and g DCW/L — subtract the blank, pick a cited factor, undo the dilution, stay in the linear window and calibrate.
- How to Count Cells with a HemocytometerTurn hemocytometer counts into cells/mL by hand: the 1e-4 mL chamber volume, why you multiply by 10⁴, the border-cell rule and dilution factor.
- How to Determine Protein Concentration from A280Determine protein concentration from A280: derive ε280 from Trp/Tyr/Cys, apply Beer–Lambert, and convert absorbance to mg/mL and µM with worked examples.
- How to Make a Buffer SolutionCalculate a buffer recipe the way the bench needs it: grams to weigh, mmol and mL of NaOH or HCl to add, the co-ions it leaves, capacity, and the checks.
- How to Make a PCR Master MixMake a PCR master mix for any recipe: solve each component with C1V1=C2V2, scale by reactions plus overage, and balance the water.
- How to Make a Serial DilutionPlan a serial dilution: choose the factor and tubes, see tube-by-tube concentrations, transfer and diluent volumes, and avoid common pipetting errors.
- How to Make a Stock SolutionMake a stock solution by weighing a solid or diluting a liquid: mass = MW × M × V, the 80% rule, hydrate and purity corrections, and per-compound recipes.
- How to Prepare a Working SolutionTurn a stock into a working solution with C1V1 = C2V2: dilution-factor table, step-by-step workflow, per-compound examples and a ratio crosswalk.
- How to Read a Punnett SquareRead a Punnett square properly: gametes in the margins, zygotes in the boxes, and how the genotype and phenotype ratios split apart.
- How to Use the Beer–Lambert LawGet a concentration from A = ε·c·l: matching units, dilution factors, transmittance, worked examples and the range where the law stops holding.
- How to Use the Hardy-Weinberg EquationUse p² + 2pq + q² properly: count alleles, square them, test the gap with the right degrees of freedom, read F, and invert a disease rate safely.
- Molarity vs MolalityMolarity is moles per litre of solution, molality per kg of solvent. See the formulas, the temperature difference, why molality exists, and M vs m vs N.
- Percent Solutions: w/v, v/v and w/wThe four percent-solution types compared side by side with formulas, units and worked examples, plus how to convert w/v to w/w using density.
- PPM to mg/LConvert ppm to mg/L and back, why 1 ppm ≈ 1 mg/L only in dilute water, and the full crosswalk to µg/mL, ppb, % and mg/m³ in air, with examples.
- What Is Molarity?Molarity is moles of solute per litre of solution. Learn the formula, M vs mM, worked examples and why temperature changes the answer.
Unit cheat-sheet
The conversions the calculators do internally, written out so you can sanity-check any result by hand.
Concentration
- 1 M = 1,000 mM = 10⁶ µM
- 1 mM = 1,000 µM = 10⁶ nM
- 1% w/v = 10 g/L = 10 mg/mL
Amount
- 1 mol = 1,000 mmol = 10⁶ µmol
- 1 µmol = 1,000 nmol = 10⁶ pmol
- n = m / MW (mass ÷ molecular weight)
Mass
- 1 g = 1,000 mg = 10⁶ µg
- 1 µg = 1,000 ng = 10⁶ pg
- 1 ppm = 1 mg/L = 1 µg/mL
Volume
- 1 L = 1,000 mL = 10⁶ µL
- 1 mL = 1,000 µL = 10⁶ nL
- C1V1 = C2V2 (dilutions)
Frequently asked questions
Are the BioSyn calculators really free?
Yes. Every calculator and guide is free to use, with no login, no subscription and no usage limit.
Do you store or upload the data I enter?
No. All calculations run locally in your browser. Your inputs never leave your device and nothing is sent to a server.
How accurate are the results?
Each tool uses standard published formulas and cites its sources. Values that depend on assumptions — such as a primer melting temperature — are clearly labelled as estimates, and the method page states its limits.
Which calculators are available right now?
The laboratory suite is live — molarity, dilution, C1V1, molar mass, stock solution, serial dilution, percent solution and ppm — along with the DNA & RNA tools (GC content, primer Tm, DNA molecular weight and DNA concentration), the PCR & qPCR tools (primer Tm, PCR master mix, qPCR efficiency and delta delta Ct), the cell culture tools (hemocytometer cell counting, trypan blue viability, seeding density, population doubling time and CFU plate counts), the protein tools (molecular weight, isoelectric point and A280 concentration), the molecular cloning tools (restriction enzyme site finder, plasmid molecular weight, ligation ratio and transformation efficiency) and the biochemistry tools (Beer-Lambert absorbance and concentration, Michaelis-Menten enzyme kinetics with kcat and inhibitor classification, and buffer formulation with titrant amounts, capacity and co-ion load) and the microbiology tools (OD600 cell density with per-organism conversion factors from BioNumbers, including dilution handling and self-calibration) and the genetics tools (Punnett square crosses from one to four genes, carrier risk across several children, conditional probabilities once a phenotype is known, X-linked crosses split by sex and linked-gene crosses driven by a recombination frequency), and the population genetics tools (Hardy-Weinberg allele and genotype frequencies from a typed sample or from a disease rate, with the chi-square test at the right degrees of freedom, the exact test for small samples, F, a 95% interval on the estimate and X-linked expectations read separately in each sex).
Can I cite or link to a calculator?
Yes. Link to the calculator page URL and cite it with the page title, BioSyn as publisher, and the last-reviewed date shown on the page.