Buying peptide in quantity changes the bench math. Instead of one vial and one tube, you may be dissolving several vials of the same lot into a single stock, then splitting that stock into a ladder of calibration standards or assay concentrations. This calculator is set up for that workflow: tell it how many vials went into the batch and the total solvent volume, and it returns the concentration of the pooled stock in mass and molar terms along with the total amount of substance.
Bulk Peptides supplies Canadian laboratories with research compounds for analytical and in-vitro work only. The calculator reflects that: it is built for HPLC and MS sample preparation, reference standard series, assay stock solutions and clean notebook records.
Preset masses are PubChem average molecular weights of the free molecule. A few need clarifying: TB-500 fragment refers to Ac-LKKTETQ (889.0 g/mol), the acetylated seven-residue sequence rather than intact thymosin beta-4; GHK-Cu refers to the 1:1 copper complex (402.9 g/mol); NAD+ refers to nadide, the free acid (663.4 g/mol). Anything outside the list goes in as Custom.
Pooling several vials into one stock
When a study needs more material than one vial holds, it is tempting to dissolve each vial separately and combine the solutions afterward. Dissolving them together into a single measured volume is cleaner: there is one final volume to record, one concentration to verify, and fewer transfers where liquid can be lost. Enter the per-vial label mass, set the vial count, and put the whole solvent volume in the volume field. The tool multiplies the per-vial peptide mass by the count before dividing by volume.
Pool only vials from one lot. Net peptide content and chromatographic purity vary slightly from lot to lot, and a stock built from two lots has a concentration nobody can trace back to a certificate. If you must combine lots, calculate each lot separately and record both.
The corrections the calculator applies
Net peptide content. Lyophilized synthetic peptide is a salt. Basic residues carry counter-ions, commonly trifluoroacetate or acetate, left over from reversed-phase purification, and the dried solid retains some water. The share of the powder that is the peptide itself is the net content, measured by amino acid analysis or nitrogen assay. 80% is the default here; a measured value is always better.
Purity. The HPLC purity value accounts for related impurities in the peptide fraction. Leave it at 100 to calculate total peptide, or enter the certificate figure to calculate the target sequence only.
Molecular weight. Because the net content step has already removed counter-ion mass, the matching molecular weight is that of the free molecule, which is what the presets provide.
peptide in stock (mg) = vials × mg per vial × net % ÷ 100 × purity % ÷ 100
stock (mg/mL) = peptide in stock ÷ total volume (mL)
stock (mM) = stock mg/mL ÷ MW × 1000
total (nmol) = peptide in stock ÷ MW × 1,000,000
Here is a batch example. Five 10 mg vials of BPC-157 at 80% net content go into 10 mL. That is 40 mg of peptide at 4 mg/mL, which at 1,419.5 g/mol is 2.818 mM, with about 28,180 nmol in the batch. One vial in 2 mL lands on exactly the same concentration, which is a quick sanity check.
Building a set of standards
A calibration curve for LC-MS or HPLC usually needs five to eight levels spanning the expected sample range. Use the second tool once per level. A practical approach is to make the top standard directly from stock, then a mid-level intermediate, and prepare the lower points from that intermediate so no single transfer is below a couple of microlitres. Switch the scale to µg/mL if your method reports mass concentration, or keep µM for molar work. Label each tube with its level, the lot number and the date as you go; it is surprisingly easy to lose track across a rack of identical tubes.
For a working reference that will be used over several days, prepare only what you need, or split the stock into single-use aliquots so the main batch is not repeatedly warmed and handled.
Where the calculator stops
These results assume ideal behavior. The tool does not account for solubility limits, adsorption to plastics, or degradation. A pooled stock at high concentration may exceed what a hydrophobic sequence will hold in solution, dilute standards can lose peptide to container walls (low-binding tubes help), and some residues oxidize in solution over time. Verify high-value stocks by an independent measurement before relying on them for quantitation.
Supporting paperwork
When a certificate is available for a lot, we post it on our COA page. Certificates are not published for every batch, so if your lot isn’t there, record the default assumptions alongside the concentration. Ordering for a larger study? Our bulk pricing is mix-and-match, so every vial in the cart counts toward the volume break.
Questions we get about this tool
Can I combine different compounds in one calculation?
No. Each compound has its own molecular weight, so calculate each separately. For a mixed standard, work out each component’s volume independently and make sure the total stays within your final volume.
What if my vials have different fill masses?
Add the label masses together, enter that total as the per-vial mass and set the vial count to 1.
Why does the vial count not change the concentration in my test?
If you scale the solvent volume by the same factor as the vial count, the concentration stays the same and only the total amount rises. That is expected.
Does the calculator remember my batches?
No. It runs in the browser and keeps nothing once the page is closed, so copy results into your lab records before leaving.
Research use only. Bulk Peptides sells its products solely for laboratory research and analytical purposes in Canada. They are not for use in humans or animals, and this calculator exists only to support the preparation and documentation of laboratory solutions.
