About
Lab-Tacular is a set of laboratory calculators that run entirely in your browser.
Working out a dilution factor, computing molarity, fitting a standard curve, evaluating quality control data — these are daily tasks in a laboratory. Most people handle them with hand-built spreadsheet formulas, or by moving between several ageing web tools. Units get entered in the wrong place; numbers get mistyped on the way from one tool to the next.
This site exists to reduce that.
The name is a blend of two words: lab, and spectacular.
How this site works
Every calculation happens in your browser.
Nothing you type is sent to a server. There is no database and no account system. Laboratory measurements and quality control records are not values that should leave your machine.
Formulas come with their reasoning.
Each tool page carries more than the calculator itself: why the equation holds, and what to watch for in practice. An answer you can judge is more useful than an answer you simply receive.
The tools do not pass judgement.
Purity ratios and coefficients of variation are shown alongside reference ranges, but the site does not mark results as passing or failing. Those thresholds depend on your laboratory and your assay, and setting them is your call.
Who made this
J. Chang
B.S. in Biotechnology
IVD Software Verification Specialist
I work in verification for in-vitro diagnostic software. Checking whether a calculation returns the right answer is my job, and these tools were built the same way. Each calculation passes an automated test suite against hand-computed expected values before it goes live.
This is a personal project, built and run independently of any employer.
How the tools are verified
Lab-Tacular goes through two kinds of verification before anything is deployed.
First, the integrity of the code. Every calculation has automated tests attached — more than 2,300 of them at the moment, across some ninety files. They run again on every change, and if a single one fails, nothing is deployed.
Second, comparison against outside sources — academic papers, standards and official documents. The list is below. Tools not in the table compute a definition (C₁V₁ = C₂V₂ and the like), which is self-evident and is not separately verified.
| Tool | Compared against | What was compared |
|---|---|---|
| Molecular Weight Calculator | IUPAC "Standard atomic weights of the elements 2021" (Pure Appl. Chem., doi 10.1515/pac-2019-0603) | The complete table of abridged standard atomic weights |
| ELISA · IC50 · Michaelis–Menten | NIST StRD certified nonlinear-regression datasets Misra1a, Rat42 and MGH09 | Certified parameters reproduced to 7–11 digits (Misra1a 11, Rat42 9, MGH09 7) and standard errors to 6–9. Rat42 and MGH09 are problems NIST rates as higher difficulty |
| Outlier test (Grubbs, Dixon's Q) | NIST/SEMATECH e-Handbook of Statistical Methods 1.3.5.17 (Grubbs) · Rorabacher 1991, Anal. Chem. 63:139 (Dixon's Q) | Ten Grubbs critical values (n = 3–20) and the worked example · 24 Dixon Q critical values |
| Unit converters (pressure, temperature, energy) | NIST SP 811 · ISO 80000-4 · ISO 80000-5 · CODATA 2022 | Defined and recommended values |
| RCF ↔ RPM converter · rotor list | Published rotor specification sheets from seven manufacturers (Thermo, Beckman Coulter, Hettich, Sigma, Sartorius, OHAUS, CRYSTE), 103 rotors | The 124 maximum and minimum RCF values printed on the sheets. Zero disagreements |
| Sample Size Calculator | Ministry of Food and Drug Safety (Korea), Guideline on clinical performance studies of in vitro diagnostic medical devices (안내서-0640-03, 2020) | Its worked example reproduced (estimate 0.80, lower bound 0.70, power 90 % → 168). The exact lower bound checked against 199 reference points computed in arbitrary precision (mpmath, 60 digits) |
| 2×2 Test Accuracy · ROC curve | MedCalc "Diagnostic test evaluation" output (2×2) · the defining equations of DeLong, DeLong & Clarke-Pearson 1988 (ROC) | 2×2: eight measures and their confidence intervals to two decimals. ROC: three small cases derived by hand from the definition, to 15 digits. Fixed in reference-value files |
| Primer Tm · primer dimer | SantaLucia 1998 (doi 10.1073/pnas.95.4.1460) · von Ahsen 2001, 2011 · Green & Sambrook 2019 | Nearest-neighbour parameters and salt corrections, from the original papers |
| Restriction map | New England Biolabs recognition-sequence data | Generated automatically; never edited by hand |
| Protein Parameters | Kyte & Doolittle 1982 · IUPAC 2021 · ExPASy ProtParam | Hydropathy scale, atomic weights, and results compared |
| SDS-PAGE gel | Bio-Rad Mini-PROTEAN Tetra Cell manual · Proteintech "SDS-PAGE Gel Recipes" | Recipe table · cassette volume table · separation range table |
Each tool page lists its own comparison sources in a "References" section; this table gathers them in one place.
Verification errors and corrections
Even with verification, human error can let something through. This is the record.
(1) The RCF ↔ RPM converter gave values ten times too large for 23 days, from 26 July to 18 August 2026.
In the centrifugal force formula RCF = 1.118 × 10⁻⁵ × r × RPM², the constant 1.118 × 10⁻⁵ is the value for a radius r entered in centimetres. Lab-Tacular's input field is in millimetres, and in millimetres the constant has to be 1.118 × 10⁻⁶. The textbook value was copied over without checking the unit, and as a result every value came out ten times too large.
For 23 days the automated tests did not catch this either. The error was noticed while a feature was being added to the tool and a manufacturer's official documentation was consulted — an outside source, not the site's own integrity checks — and it was then corrected.
After the fix, the following was improved.
- The constant was corrected to 1.118 × 10⁻⁶. (18 August 2026)
- A test was added that pins the calculated value to the RCF values manufacturers print. If the constant is wrong, this test fails.
- A test comparing the constant in the page text with the constant in the code was added in all four languages. (20 August 2026) If the text and the code disagree, it fails.
Since this incident, Lab-Tacular carries out external verification, where it is possible, of both the existing tools and newly added features before they are deployed.
Scope and limits
The tools on this site are intended to support calculations for research and laboratory work.
- They are not designed for medical diagnosis or treatment decisions
- There is no facility for entering patient information, and none should be entered
- This is not a regulated medical device and has not been validated as one
- Final responsibility for verifying any result rests with the user
Where your laboratory's standard operating procedures differ from the guidance here, follow your procedures.
Found something wrong?
If a formula is incorrect, or a note does not match practice, please tell me. I will check it and fix it.
Contact: contact@lab-tacular.com