Laboratory tools
Peptide Calculator
Free reference tools for research peptides: solution concentration after reconstitution, C₁V₁ = C₂V₂ dilutions, mass ↔ molarity, aliquot planning and sequence properties. Results update as you type and nothing is sent to a server.
Tool 01
Reconstitution Calculator
Enter the peptide mass on the vial label and the volume of diluent added. You get the stock concentration and the volume that holds a chosen mass of peptide.
Measured content from the certificate of analysis ÷ label mass. Leave at 100 % to use the label mass.
- Concentration
- –mg/mL
- Volume for target
- –µL
- Draws per vial
- –
- Per 100 µL
- –µg
–
Volume for nearby masses
Laboratory reference only. Volumes are for preparing research solutions; no administration is implied. Check the measured content on the batch certificate of analysis before relying on the label mass.
Tool 02
Dilution Planner (C₁V₁ = C₂V₂)
How much stock to transfer and how much diluent to add to reach a target concentration and final volume. Switch to serial mode for a fixed-factor series.
Stock and target use the same unit.
- Stock to transfer
- –
- Diluent to add
- –
- Dilution factor
- –
| Tube | Concentration | Transfer in | Diluent |
|---|
C₁ × V₁ = C₂ × V₂ → V₁ = (C₂ × V₂) ÷ C₁
Tool 03
Mass ↔ Molarity Converter
Convert a peptide mass in a volume to molar concentration, or find the mass to weigh for a target molarity. Pick a compound to fill in its molecular weight.
Acetate or TFA salt powders often assay 70–90 % peptide. Leave at 100 % if the vial is filled to net peptide.
- Molar concentration
- –
- Total substance
- –µmol
- Mass concentration
- –mg/mL
- Powder to weigh
- –mg
Equal to the peptide mass at 100 % net content.
moles = mass (g) ÷ MW (g/mol) · molarity (M) = moles ÷ volume (L)
Tool 04
Aliquot & Storage Planner
Split a reconstituted stock into single-use tubes, allowing for the volume left behind in each tube, and see general stability ranges by temperature.
Film left behind when the tube is emptied. Set to 0 to ignore.
–
- Volume per aliquot
- –µL
- Peptide per aliquot
- –mg
- Concentration
- –mg/mL
- Recoverable per tube
- –µg
peptide per aliquot = (peptide ÷ reconstitution volume) × aliquot volume
Storage temperature & typical stability
+20 °CRoom temperature
- Lyophilised
- Weeks — transit only
- In solution
- Hours — one working session
+4 °CRefrigerated
- Lyophilised
- Months
- In solution
- About 2–4 weeks
−20 °CFreezer
- Lyophilised
- 1–2 years
- In solution
- 1–3 months as single-use aliquots
−80 °CUltra-low freezer
- Lyophilised
- Several years
- In solution
- 6–12 months as single-use aliquots
General handling ranges, not a substitute for the stability data on a specific certificate of analysis. Peptides containing Met, Cys or Trp oxidise faster; protect them from light and air. Avoid repeated freeze–thaw: a single-use aliquot is thawed once.
Tool 05
Sequence Property Analyser
Paste a one-letter amino acid sequence to estimate molecular weight, isoelectric point, net charge at pH 7, GRAVY hydropathy and ε₂₈₀. Assumes free termini, reduced cysteines and standard L-amino acids.
- Residues
- –aa
- Molecular weight
- –Da
- Isoelectric point
- –pI
- Net charge · pH 7
- –
- GRAVY
- –
- ε₂₈₀ (reduced)
- –M⁻¹cm⁻¹
Net charge vs pH · –
Solvent selection
–
Concentration check by A₂₈₀
–
Values are calculated from the primary sequence. Acetylation, amidation, cyclisation, non-standard residues and counter-ions all shift the real figures; treat them as a starting point, not as a certificate of analysis.
How the calculations work
Concentration after reconstitution
C (mg/mL) = peptide mass (mg) ÷ diluent volume (mL). 10 mg in 2 mL is 5 mg/mL, which is 5,000 µg/mL or 5 µg per µL. The volume holding a target mass is V = mass ÷ C.
Net peptide content
The label mass and the measured content of a vial can differ. Our certificates of analysis report the measured result; enter measured ÷ label as the net content so the concentration reflects what the lab found.
Dilution and serial dilution
C₁V₁ = C₂V₂. To go from 5 mg/mL to 1 mg/mL in 1,000 µL, transfer 200 µL of stock into 800 µL of diluent. A serial series repeats the same factor from each new tube.
Mass to molarity
M = mass (g) ÷ MW (g/mol) ÷ volume (L). 10 mg of BPC-157 (1,419.5 g/mol) in 2 mL is 3.52 mM. Reverse it to find the mass to weigh for a target molarity.
Isoelectric point and solubility
The pI is the pH at which a peptide's positive and negative charges cancel, where solubility is lowest. Acidic peptides (pI below 6) dissolve best slightly above their pI; basic peptides slightly below.
Concentration by A₂₈₀
Tryptophan (5,500 M⁻¹cm⁻¹) and tyrosine (1,490 M⁻¹cm⁻¹) absorb at 280 nm. A sequence with neither cannot be measured this way; use the HPLC content on the certificate instead.
Molecular weight reference
Free peptide (non-salt) values used by the converter. Lot-specific figures are on each certificate of analysis.
| Compound | MW (g/mol) | Sequence |
|---|---|---|
| Cortagen | 430.41 | AEDP |
| Cardiogen | 489.49 | AEDR |
| BPC-157 | 1,419.53 | GEPPPGKPADDAGLV |
| TB-500 (Thymosin β4) | 4,963.44 | SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES |
| Epitalon | 390.35 | AEDG |
| KPV | 342.44 | KPV |
| Selank | 751.88 | TKPRPGP |
| Semax | 813.93 | MEHFPGP |
| DSIP | 848.81 | WAGGDASGE |
| Kisspeptin-10 | 1,302.51 | YNWNSFGLRF |
| MOTS-c | 2,174.56 | MRWQEMGYIFYPRKLR |
| Thymosin α-1 | 3,108.33 | SDAAVDTSSEITTKDLKEKKEVVEEAEN |
| GHK-Cu | 402.92 | — |
| Ipamorelin | 711.85 | — |
| CJC-1295 (no DAC) | 3,367.86 | — |
| Tesamorelin | 5,135.87 | — |
| SS-31 | 639.79 | — |
| AOD-9604 | 1,817.09 | — |
| IGF-1 LR3 | 9,117.50 | — |
| Tirzepatide | 4,813.45 | — |
| Retatrutide | 4,731.32 | — |
| Cagrilintide | 4,409.00 | — |
| NAD+ | 663.43 | — |
| Glutathione (reduced) | 307.32 | — |
