Lab calculators

What the lab calculators are

Bench work is full of small calculations. How much powder to weigh out for a stock, how much to add for a dilution, what the melting temperature of a primer is, how many picomoles are in a microgram of DNA. The lab calculators gather the common ones into a single floating modal so you can do the math without leaving ResearchOS and without reaching for a separate tool.

The calculators live behind a small floating beaker button that sits in the corner of the app. Clicking it opens the calculators modal over whatever you are working on; closing it returns you exactly where you were. The modal is a scratchpad, not a record. It does not write to your data folder, it is not attached to an experiment, and it keeps no history. As the footer of the modal says, this is quick bench math computed live in your browser, and nothing here is saved.

The calculators

The modal carries one tab per calculator. Each tab is self-contained, so you fill in the fields it needs and the result appears below, updating on every keystroke. Most tabs accept values with a unit selector (nM, uM, mM, M for concentration; uL, mL, L for volume; ng, ug, mg, g for mass), and the result is shown in whatever unit reads most naturally for the number.

Scientific

A general-purpose scientific calculator for the arithmetic that does not fit the other tabs. Type an expression directly or use the on-screen keypad. It handles the usual operators plus sine, cosine, tangent and their inverses, the natural log and log base 10, square root, powers, factorial, and the constants pi and e. A degree or radian toggle sets the angle mode, and a small memory (M, with recall and add) holds a running value. Enter sets the last answer so you can chain calculations.

Molarity

The weigh-out calculator. Enter a molecular weight, a target concentration, and a volume, and it gives the mass to weigh out, using n = m / MW and C = n / V. Enter a mass instead and it goes the other way, giving the moles and the resulting concentration. This is the everyday make-a-stock calculation.

Dilution

The C1 V1 = C2 V2 calculator. Enter your stock concentration, the final concentration you want, and the final volume, and it solves for how much stock to add and how much diluent to top up with. It flags the case where the final concentration is higher than the stock, which usually means an input slipped.

Serial dilution

Builds a serial-dilution table. Give a starting concentration, a fold factor per step, a number of steps, and a per-tube final volume, and it lays out each tube with the concentration at that step, the volume of sample to carry over from the previous tube, and the volume of diluent to add. Each tube takes a fixed transfer of the previous one and tops up to the per-tube volume, giving an equal fold dilution per step.

Primer Tm

The primer melting-temperature calculator. Paste a DNA or RNA sequence and it reports the length, the GC content, and the melting temperature using a nearest-neighbor model (the SantaLucia parameters that IDT OligoAnalyzer, Primer3, NEB, Benchling, and SnapGene use). Only the sequence is required, standard reaction conditions are assumed, and an Advanced section lets you enter your actual salt, Mg2+, dNTP, and oligo concentrations for a sharper value. For very short oligos it also shows the Wallace 2-4 rule, where the rule of thumb still helps. This is the same Tm engine that powers the live selection readout and the primer-design dialog in the Sequences editor, so a Tm you compute here agrees with one you compute there.

DNA / RNA

Two nucleic-acid conversions in one tab. The mass-to-moles section turns a mass and a length into an amount, choosing the right average molecular weight for double-stranded DNA, single-stranded DNA, or RNA. The A260 section turns a spectrophotometer reading and a dilution factor into a concentration in ng/uL, using the conventional ng-per-A260 factor for each nucleic-acid kind.

Protein properties

Paste an amino-acid sequence and it reports the same physico-chemical properties the ExPASy ProtParam tool reports, including the average molecular weight, the isoelectric point (pI), the molar extinction coefficient at 280 nm and the corresponding absorbance of a 0.1 percent solution, the amino-acid composition, the instability index, the GRAVY hydropathy, the aromaticity, and the aliphatic index. The readout is the same one the editor's Analyze menu shows, so the calculator and the editor agree.

Buffer recipe

Build a multi-component buffer. Set the total volume, then add a row per component with its final concentration and its stock concentration. For each component it gives the volume of stock to add, using volume = (final concentration x total volume) / stock concentration, and it reports the diluent to top up with. It flags the case where the stock volumes alone overflow the total volume.

Build your own calculator

The calculators above are fixed, and the math you do in them is scratch. Plenty of bench math is too specific to ship for everyone, though. A spore suspension from five hemocytometer counts, a master mix scaled to your reaction count, a dosing volume from an animal's weight. So you can build your own calculator for the math your lab actually does. Unlike the built-in tabs, a calculator you build is saved, as its own item in your folder, and you can share it and use it on your phone.

Open the Lab calculators modal and, alongside the built-in tabs, you will find your own calculators, a Build your own button, and a template library. A calculator you build is just inputs and a formula. You name the things you measure, you write the answer as a formula using those names, and the result computes live as you fill it in, exactly like the built-in tabs.

How you build one

The first time, a short wizard walks you through it one plain question at a time. What does this work out, what do you measure, what is the formula, any warnings to add, and what is the answer called. It assembles the calculator for you, with the answer updating live on the formula step so you can see it working before you save.

Once you have built one, Build your own opens a single form instead, with the same pieces laid out together. You can switch between the wizard and the form at any time, and your work carries across. The form keeps the simple case simple, the optional pieces (intermediate steps and guidance warnings) sit behind an Advanced section, so a basic calculator is just inputs and a result.

Start from a template

You rarely need to start from a blank page. The template library carries ready-made calculators grouped by field, including spore concentration, CFU per mL from plate counts, OD600 to cell density, qPCR amplification efficiency, and doubling time. Open the closest one, change the parts that differ for your lab, and save it as your own. Cloning and tweaking a real example is faster than building from scratch, so it is how most calculators start.

Inputs, formulas, and guidance

An input is a box you type a measurement into. You name it in plain words and the builder gives it a short name to use in formulas, so labelling one Average spore count lets you reference it as avgCount. An input can be a single number, a dropdown of choices, or a replicate list (several values you average, like five squares on a hemocytometer). The result is a formula written with those names, and helpers like mean, sum, and standard deviation are there for the replicate case.

Guidance is the optional safety net. You write a condition and a message, and the message only appears when the condition is true. A spore calculator can warn you when the count is too low to be reliable, a qPCR calculator can flag an efficiency outside the accepted range. The warning stays quiet until something is actually off. Each answer can also be shown the way you read it, a plain number, scientific notation, or a fixed number of decimals.

Sharing and your phone

A calculator you build is yours until you share it. Share it with your lab and everyone in your lab folder can run it as a live reference, so they always see your latest and you stay the only editor. Share it with someone outside your folder and a copy travels to them over the encrypted transfer relay. And when your phone is paired to your laptop, your calculators sync to it automatically, so the math you built at the bench is on the bench with you. The companion app ships with the built-in calculators and pulls your custom ones in once it is paired.

Submitting to the public library

If you build a calculator others would find useful, you can submit it to the public template library. It opens a pre-filled submission on our GitHub for a maintainer to review, and accepted calculators ship in a later release for everyone to start from. It is reviewed rather than instant, so the shared library stays trustworthy.