A worked example for each of 56 calculations, drill problems for 31 of them, and 8 reference tables. Every number on every page is computed by the same tested calculator the rest of the site uses, so a solution cannot drift away from the maths.
Reference
Chemical shifts for residual solvents and the trace impurities that show up in almost every 1H spectrum, in the eight deuterated solvents used most. Read across the row for the same impurity in a different solvent.
pKa at 25 C for the buffers used on a biochemistry bench, with the temperature coefficient that tells you how far the pH moves when you take the buffer to the cold room. A buffer only buffers within about one pH unit of its pKa.
Every GHS hazard statement code with its official wording, as it appears on a reagent label and in section 2 of a safety data sheet.
Every GHS precautionary statement code with its official wording: the prevention, response, storage, and disposal advice printed on a reagent label.
Adduct masses for electrospray mass spectrometry: what to add to the neutral monoisotopic mass, and what to divide by, to predict an observed m/z. Useful in reverse too, for identifying an unexpected peak as sodium rather than a product.
Antoine coefficients in the form log10(P in bar) = A - B / (T in K + C), with the temperature range each fit is valid over. Use them to predict a solvent’s vapour pressure, or the bath temperature a rotary evaporator needs at a given pressure.
Average residue masses for the twenty amino acids, which is what you sum to get a peptide or protein molar mass, plus the extinction contributions used to predict absorbance at 280 nm.
Exact conversion factors for the older units still printed on gauges, in patents, and in papers from before SI: atmospheres, Torr, mmHg, psi, calories, electronvolts, poise, and kilogram-force.
Henderson-Hasselbalch, the acid/base split for a target pH.
Dial in the bench pH so your buffer hits target at working temperature.
Target pH and stocks in, an exact volume-closed recipe out.
Overshot your buffer? Get the exact strong acid or base volume to fix it.
Build a multi-component buffer from stocks and solids.
OD600 to cells per mL, and back-dilute a culture to a target OD.
A SMILES to its formula, molar mass, exact mass, and isotope pattern. Invalid valence is flagged, never guessed.
Convert between molarity, mass, volume, and moles for a reagent, in any direction.
Type an element or formula (Sb, NaCl, C6H12O6) and convert grams to moles. Molar mass is computed from cited atomic weights.
Convert %w/v, %w/w, %v/v ⇄ g/L and molarity.
C₁V₁ = C₂V₂, exactly how much stock and diluent to mix.
A fold-dilution series, tube by tube.
Turn a bottle label (%w/w + density) into a safe dilution protocol.
Grams of agarose for a % gel and casting volume.
Resolving & stacking gel recipes by acrylamide %.
Resuspend a lyophilized primer to a stock concentration.
Convert a dsDNA mass to moles (and back) from its length.
Insert mass for a target insert:vector molar ratio.
DNA and RNA concentration and purity from absorbance.
Mass, molarity, and copies/µL for dsDNA, ssDNA, or ssRNA, both directions.
Nearest-neighbor Tm with Na+ and Mg2+ salt corrections. Not a Wallace guess.
Vector amount and insert ratios to an exact pipetting table.
Livak 2^-ddCt with proper error propagation and an honest asymmetric band.
Colonies, plated fraction, and DNA mass to CFU per µg.
Scale a per-reaction recipe to a batch, with overage.
Antoine vapor pressure of a solvent, and the boiling point at each vacuum setpoint.
Identify a 1H peak from its shift, or look up where a known compound appears (Fulmer table).
Convert electrophoretic mobility to zeta potential (Henry / Smoluchowski / Huckel).
Scale flow, injection, and gradient between columns, with void volume and dead time.
Convert Torr, atm, psi, cal, eV, poise, dyne and other legacy units to SI.
Turn weighed water masses into accuracy and precision against the nominal volume.
Build the health / flammability / instability / special hazard diamond.
Remaining radioactivity after time, by half-life.
Rotor clearing factor and pelleting time.
Total osmolarity of a multi-solute solution.
Convert centrifuge speed to g-force using the rotor radius.
Protein concentration from absorbance and extinction coefficient.
Total units and specific activity from a measured rate.
Fit a linear or quadratic standard curve (Bradford, BCA, ELISA) and read unknowns.
Weigh a solid or pipette a liquid: enter what you have, get the bench step.
Weighed the wrong amount? Get the volume to dissolve it in to hit your target.
Protocol assumes one hydrate, you have another? Get the corrected mass.
I = ½ Σ cz², plus activity coefficients (Debye-Huckel to Davies).
N = M × n, with the equivalence factor you confirm for the reaction.
Sequence to ε280, MW, and E0.1%, the Pace way. Feeds the A280 calculator.
Formula or mass to adduct m/z, and reverse-match an observed peak by ppm.
Concentration from absorbance, any extinction-coefficient convention.
Flag a suspect replicate (3 to 10 values). Advisory only, never auto-deleted.
Fit a dose-response curve and read off the IC50/EC50, Hill slope, and R².
Fit enzyme kinetics to read Vmax, Km, and (with [E]t) kcat and kcat/Km.
Welch's t-test for two groups: p-value, effect size, and a plain verdict.
Fit a standard curve, subtract the blank, and back-calculate protein with dilution.
Loading-control-normalized densitometry: relative density and fold change vs control.
Pin the scale, get every reagent’s mmol, mass, and volume from its equivalents.
Exact integer coefficients by rational null-space. Unbalanceable input is flagged, never fudged.
Which reagent runs out, the theoretical yield, and what is left over.
The calculators, the working, the hazard flags, the explainers, the practice problems, and the reference tables. No account, no signup, and it keeps working offline once a page has loaded.
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