Calculator
Formula Used
1 kDa = 1000 Da
1 Da is numerically equal to 1 g/mol.
Total molecular weight = kDa × oligomer count × 1000
Mass per molecule = molecular weight in g/mol ÷ 6.02214076 × 10²³
mg/mL = concentration in µM × total kDa ÷ 1000
How to Use This Calculator
- Enter the molecular weight value in kDa.
- Enter the oligomer count if the molecule forms a complex.
- Add concentration in µM if you need mg/mL.
- Select the decimal precision for the final output.
- Press the calculate button.
- Review the result above the form.
- Download the result as CSV or PDF when needed.
Example Data Table
| kDa | Da | g/mol | kg/mol | Estimated Residues |
|---|---|---|---|---|
| 10 | 10,000 | 10,000 | 10 | 90.91 |
| 25 | 25,000 | 25,000 | 25 | 227.27 |
| 50 | 50,000 | 50,000 | 50 | 454.55 |
| 66 | 66,000 | 66,000 | 66 | 600 |
| 100 | 100,000 | 100,000 | 100 | 909.09 |
Understanding kDa and Molecular Weight
Kilodalton, written as kDa, is a common mass unit in biology. It describes the molecular weight of proteins, peptides, enzymes, and other large molecules. One kilodalton equals one thousand daltons. A dalton also matches one gram per mole as a molar mass value. This makes kDa useful when comparing a molecule on a laboratory report, gel result, or product sheet.
Why This Conversion Matters
Researchers often receive molecular weight in kDa, but calculations may need daltons, grams per mole, kilograms per mole, or mass per molecule. These units support concentration work, sample preparation, dosing estimates, and documentation. A protein marked 50 kDa has a molar mass of 50,000 g/mol. The same value can also be expressed as 50,000 Da.
Advanced Options
This calculator adds helpful controls beyond a basic unit change. You can enter an oligomer count to estimate the total molecular weight of a dimer, trimer, tetramer, or larger complex. You can also enter micromolar concentration. When concentration is supplied, the tool estimates milligrams per milliliter. This is useful because many protein protocols move between molar concentration and mass concentration.
Interpreting Results
The result panel shows each conversion clearly. It includes daltons, grams per mole, kilograms per mole, and the mass of one molecule in grams and kilograms. The calculator also estimates amino acid count with the common average residue mass of 110 Da. This is only an estimate. Actual sequence composition, tags, modifications, glycosylation, and cleavage can change the true molecular weight.
Common Use Cases
Use kDa conversion when reviewing antibody datasheets, protein ladders, purification notes, and molecular biology protocols. It also helps teaching pages because students can see how one compact value expands into several scientific units. The table and downloads make repeated examples easier to save. They also help teams compare values without rebuilding the same calculation in a spreadsheet. You can reuse them during reviews, lessons, and audits.
Best Practice
Use the calculator for planning, checks, and quick reporting. For final regulated work, confirm molecular weight from a trusted sequence tool, certificate, or analytical method. Keep your original kDa value with the exported file. This makes later review easier and reduces transcription mistakes in shared laboratory records.
FAQs
What does kDa mean?
kDa means kilodalton. It is a molecular mass unit. One kDa equals 1000 daltons. It is often used for proteins, peptides, antibodies, and enzymes.
How do I convert kDa to molecular weight?
Multiply the kDa value by 1000. The answer gives daltons. The same number also represents grams per mole for molar mass calculations.
Is kDa the same as g/mol?
They are not the same unit, but they are numerically connected. One dalton corresponds to one gram per mole when expressing molar mass.
What is the molecular weight of 50 kDa?
50 kDa equals 50,000 daltons. It also equals 50,000 g/mol. For a monomer, that is the listed molecular weight.
Why add an oligomer count?
Some proteins form dimers, trimers, tetramers, or larger complexes. The oligomer count estimates total molecular weight for the complete complex.
How is mg/mL calculated from µM?
The calculator multiplies µM by total kDa, then divides by 1000. This gives an estimated protein concentration in mg/mL.
Is the amino acid estimate exact?
No. It uses an average residue mass of 110 Da. Real sequence composition, tags, and modifications can change the exact value.
Can I export the calculated result?
Yes. Use the CSV button for spreadsheet records. Use the PDF button for a clean report copy of the current calculation.