Bench Calculators
These are the numbers you need before you touch anything: how much to weigh, how far to dilute, how fast to spin, how much to plate.
The three most used are molarity, dilution and percent concentration. They are three phrasings of the same equation, kept separate because the real difficulty at the bench is not the arithmetic but the units: mg/mL and M differ by a molecular weight, % (w/v) and % (v/v) are not the same quantity, and ppm approximates mg/L only in dilute aqueous solution.
Read the two centrifugation tools together: RCF / RPM answers “how fast is this machine spinning”, while rotor k-factor answers “does this protocol still hold in a different rotor” — at identical g-force, two rotors can differ threefold in the time needed, which is routinely missed.
The cell tools divide cleanly: hemocytometer counts, OD₆₀₀ conversion measures, split ratio works backwards, and plate colony counting explains why the countable range is 30–300 — that is not a convention, it follows from 1/sqrt(n) counting precision.
The recurring trap here is entering a total where a per-unit value is asked for. Every tool that supports batches multiplies by the count again, so the answer is wrong by exactly that factor — and it looks perfectly reasonable.
Bench calculators
Centrifuge RCF (g) ↔ RPM Converter — Relative Centrifugal Force Calculator
Convert between relative centrifugal force (× g) and rotor speed (rpm) in both directions using rotor radius, with common reference values.
Molarity, Mass, and Volume Calculator — Solve for Concentration, Volume, or Mass
Solve for concentration, volume, or mass given the other two — supports mM/µM/nM and mg/µg/ng.
Solution Dilution Calculator (C1V1 = C2V2)
Calculate stock, fold, and serial dilutions in one step — outputs the exact solvent volume to add.
Nucleic Acid Concentration Calculator: OD260, ng/µL, and pmol Conversion
Convert A260 absorbance to mass concentration and interconvert ng and pmol for dsDNA, ssDNA, RNA, and oligonucleotides.
Hemocytometer Cell Concentration Calculator
Enter counts from each large square and the dilution factor to calculate cell concentration, total cell number, and volume needed for plating.
Buffer Preparation Calculator (Henderson-Hasselbalch)
Calculate the acid/base component ratio and the mass of each needed to hit your target pH.
PCR Reaction Setup Calculator (with Multi-Sample Master Mix)
Calculate the volume of each component and water make-up from stock and final concentrations; supports batch master mix preparation for multiple samples.
DNA / RNA Copy Number Calculator (Plasmid Standards, qPCR, ddPCR)
Calculate copies/µL, copies per reaction, and single-copy mass from concentration and length; generate a standard-curve dilution series.
Primer Resuspension and Dilution Calculator
How much water to add for lyophilized primer resuspension, how to dilute to working stock, and how many reactions your tube will support.
Transformation Efficiency Calculator
Calculate transformation efficiency in CFU/µg with automatic plating-ratio correction — omitting this step throws your result off by 10-fold or more.
Cell Culture Vessel Converter — Surface Area, Seeding Density & Drug Volume
Scale seeding cell counts and drug volumes between culture plates, dishes, and flasks: cell number follows area, drug volume follows medium — and these ratios differ.
Percent Concentration Converter (% w/v, % w/w, % v/v, ppm ↔ mol/L)
The 37% on the bottle and 12 mol/L in the protocol are the same concentrated HCl — convert between % (w/v), % (w/w), % (v/v), ppm, g/L, and mol/L in one step.
OD₆₀₀ to Cell Concentration Calculator (Dilution Correction / Plate Reader Path-Length / Inoculum Back-Calculation)
Convert OD₆₀₀ readings to cells/mL and total cell count, with dilution back-calculation, path-length correction, and linear-range checking.
Gel Band Size Estimation (DNA bp / Protein kDa, Semi-log Standard Curve)
Fit a semi-log curve to marker migration distances and estimate unknown band sizes; flags linear-interpolation overestimation and out-of-range extrapolation.
Cell Split Ratio & Regrowth Time Calculator — Back-Calculate the Right 1:N Ratio from Doubling Time
Calculate regrowth time after a 1:N cell split, or back-calculate the ratio needed. Diluting twice as much buys only one extra doubling, not twice the time.
Plate Colony Count and CFU/mL Calculator (Countable Range / ISO Weighted Average / Poisson Error)
Enter colony counts by dilution; the tool picks countable plates, applies ISO 4833 weighted average, and returns CFU/mL with Poisson error — limits from 1/√n.
Centrifuge k-Factor Calculator: Convert Run Time When Switching Rotors
Compute rotor k-factor from r_min, r_max, and rated speed; scale run time when switching rotors. RCF measures force — k accounts for path length too.
Animal Dose Calculator — mg/kg to Injection Volume & Batch Preparation
Enter dose (mg/kg), body weight, and stock concentration to get injection volume; supports batch preparation and shows maximum volumes by route.
Bacterial / Cell Doubling Time and Growth Rate Calculator
Enter two log-phase OD or cell count measurements to calculate doubling time, specific growth rate μ, number of generations, and predicted cell density.
DNA Ligation Calculator — Vector and Insert Amount (T4 Ligase)
Enter linearized vector amount and size, insert size, and molar ratio to calculate required insert mass and fmol values for T4 ligase cloning.
Multiplicity of Infection (MOI) Calculator
Enter cell count, target MOI, and viral titer to get the required virus volume; Poisson-based infection rate and single-infection fraction; back-calculate actual MOI from measured infection rate.
SDS-PAGE Gel Preparation Calculator (Resolving Gel & Stacking Gel)
Enter acrylamide percentage and per-gel volume; calculate acrylamide, Tris, SDS, APS, TEMED, and water for both gel layers, with multi-gel batch scaling.
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