Peptide Calculator — Reconstitution, Dilution, Molarity, Aliquots & Sequence Properties
Free laboratory reference tools for research peptides. Work out solution concentration from vial mass and diluent volume, plan C₁V₁ = C₂V₂ dilutions, convert mass to molarity with 24 compound presets, split a stock into aliquots, and estimate molecular weight, pI and GRAVY from a sequence. Results update as you type; nothing is sent to a server.
Tool 01
Reconstitution Calculator
Enter the peptide mass on the vial label and the volume of diluent added. The tool returns the stock concentration and the volume that contains a chosen mass of peptide.
50 µL
on a 50 µL scale
Research solution, pipette.
C = 10 mg ÷ 2 mL = 5 mg/mL · V = 250 µg ÷ 5000 µg/mL = 50 µL
Volume for Neighbouring Masses
Peptide in Vial
Peptide mass printed on the vial label, in milligrams.
Diluent Added
Volume of diluent added to the vial, in millilitres.
Target Mass per Draw
Mass of peptide you want the drawn volume to contain, in micrograms.
Net Peptide Content
From the lot's certificate: measured mg ÷ labelled mg × 100. Leave at 100 to use the label value.
Draw Volume
50 µL
on a 50 µL scale
Research solution, pipette.
Stock Concentration
5mg/mL
Volume for Target Mass
50µL
Draws per Vial
40draws
C = 10 mg ÷ 2 mL = 5 mg/mL · V = 250 µg ÷ 5000 µg/mL = 50 µL
Volume for Neighbouring Masses
Laboratory reference only. Volumes are for pipetting research solutions; no administration is implied. Verify the measured content on the lot’s certificate of analysis before relying on the label mass.
Tool 02
Dilution Planner (C₁V₁ = C₂V₂)
Volume of stock to transfer, and diluent to add, to reach a target concentration and final volume. Switch to serial mode for a fixed-factor series.
C₁ × V₁ = C₂ × V₂ → V₁ = (C₂ × V₂) ÷ C₁
Transfer
Stock
10 mg/mL
Working
1 mg/mL
dashed line = stock aliquot
Stock to transfer
0.1mL
100 µL
Diluent to add
0.9mL
Dilution factor
1 : 10
Tool 03
Mass ↔ Molarity Converter
Convert a peptide mass in a given volume to molar concentration, or find the mass to weigh for a target molarity. 24 compound presets with molecular weights of the free peptide.
moles = mass (g) ÷ MW (g/mol) · molarity (M) = moles ÷ volume (L)
Prepared vial
2.50 mg/mL
2 mL fill
Molar concentration
1.761mM
Total substance
3.522µmol
Mass concentration
2.500mg/mL
Powder to weigh
5.000mg
Equal to peptide mass at 100 % net content.
Where this lands · log scale
Tool 04
Aliquot & Storage Planner
Split a reconstituted stock into single-use tubes, accounting for dead volume, and see general stability ranges by temperature.
mass per aliquot = (peptide ÷ reconstitution volume) × aliquot volume
Aliquot rack
10 × 200 µLthe vial divides evenly
Volume per aliquot
200µL
Peptide per aliquot
1.00mg
Concentration
5.00mg/mL
Recoverable per tube
975µg
2.5 % held back as dead volume
Storage temperature & expected stability
- Lyophilised
- Weeks — shipping window only
- In solution
- Hours — working session only
- Lyophilised
- Months
- In solution
- 2–4 weeks in solution
- Lyophilised
- 1–2 years
- In solution
- 1–3 months as single-use aliquots
- Lyophilised
- Several years
- In solution
- 6–12 months as single-use aliquots
Ranges are general handling guidance for research peptides and are not a substitute for the stability data on a specific certificate of analysis. Peptides containing Met, Cys or Trp oxidise faster than the table suggests; protect those from light and headspace oxygen.
General handling ranges for research peptides; they are not a substitute for stability data on a specific certificate of analysis. Avoid repeated freeze–thaw: single-use aliquots go through the cycle 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.
One-letter sequence
Residues — 15 total
Composition
Residues
15aa
Molecular weight
1419.55Da
Average mass, free acid, unmodified termini.
Isoelectric point
3.88pI
Estimated from side-chain pKa values.
Net charge · pH 7
-2.02
GRAVY
-0.693
Negative — net hydrophilic.
ε₂₈₀ (reduced)
0M⁻¹cm⁻¹
Buffer pH
pH 7.4 · net charge -2.06Net charge vs pH
pH 7.4 → -2.06x: pH · y: net charge · drag or hover to read the curve
Concentration check by A₂₈₀
No tryptophan or tyrosine, so this peptide has essentially no absorbance at 280 nm and A₂₈₀ cannot be used to check its concentration. Use a colorimetric assay (BCA) or quantitative amino-acid analysis instead — a reading at 205–214 nm on the peptide bond is possible but far more sensitive to buffer interference.
Values are computed from the primary sequence assuming free (unmodified) N- and C-termini, all cysteines reduced, and standard L-amino acids. Acetylation, amidation, cyclisation, non-standard residues and counter-ions all shift the real figures — treat these as a starting point, not as a certificate of analysis.
Understanding the Maths Behind Each Tool
Concentration from reconstitution
C (mg/mL) = peptide mass (mg) ÷ diluent volume (mL). 10 mg in 2 mL gives 5 mg/mL, which is 5,000 µg/mL or 5 µg/µL. The volume holding a target mass is V = mass ÷ C.
Net peptide content
A vial’s label mass and its measured content differ. Every Eppix Labs certificate reports both; enter measured ÷ labelled as the net content so concentrations reflect what the lab found rather than the nominal figure.
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 and solubility is at its minimum. Acidic peptides (pI below 6) dissolve best slightly above their pI; basic peptides slightly below.
Concentration by A₂₈₀
Tryptophan (5,500) and tyrosine (1,490 M⁻¹cm⁻¹) absorb at 280 nm. A sequence with neither cannot be quantified this way — use the certificate’s HPLC content instead.
Molecular Weight Reference — Research Peptides
Free peptide (non-salt) values used by the converter. Lot-specific figures are on each certificate of analysis.
| Compound | MW (g/mol) | Notes |
|---|---|---|
| BPC-157 | 1,419.5 | Sequence: GEPPPGKPADDAGLV |
| TB-500 (Thymosin β4) | 4,963.4 | Sequence: SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES |
| GHK-Cu | 403.9 | Copper complex; GHK free tripeptide is 340.38 Da. |
| KPV | 342.4 | Sequence: KPV |
| Ipamorelin | 711.9 | Contains non-standard residues (Aib, 2-Nal). |
| CJC-1295 (no DAC) | 3,367.9 | Also sold as Mod GRF 1-29. |
| Tesamorelin | 5,135.9 | — |
| Semax | 813.9 | Sequence: MEHFPGP |
| Selank | 751.9 | Sequence: TKPRPGP |
| Epitalon | 390.4 | Sequence: AEDG |
| Melanotan II | 1,024.2 | Cyclic; contains D-Phe and Nle. |
| PT-141 (Bremelanotide) | 1,025.2 | — |
| MOTS-c | 2,174.6 | Sequence: MRWQEMGYIFYPRKLR |
| SS-31 | 639.8 | Contains D-Arg and Dmt. |
| Thymosin α-1 | 3,108.3 | N-terminally acetylated in the native form. |
| AOD-9604 | 1,817.1 | — |
| Kisspeptin-10 | 1,302.5 | Sequence: YNWNSFGLRF |
| DSIP | 848.8 | Sequence: WAGGDASGE |
| IGF-1 LR3 | 9,117.5 | 83-residue analogue. |
| Tirzepatide | 4,813.5 | — |
| Retatrutide | 4,731.3 | — |
| Cagrilintide | 3,748.2 | — |
| NAD+ | 663.4 | Dinucleotide, not a peptide. |
| Glutathione (reduced) | 307.3 | γ-linked at Glu; sequence shown for composition only. |
Peptide Calculator Questions
Divide the peptide mass on the vial by the volume of diluent added. 10 mg in 2 mL is 5 mg/mL. Use the measured content from the lot’s certificate instead of the label mass for an exact figure.
mg/mL is mass per volume; molarity (mol/L) is number of molecules per volume and depends on molecular weight. The same 5 mg/mL is 3.52 mM for BPC-157 (1,419.5 g/mol) but only 1.04 mM for tirzepatide (4,813.5 g/mol).
Because labelled mass and measured mass differ. Eppix Labs certificates publish the measured milligrams for every lot; entering that ratio makes the concentration match what is actually in the vial.
Computed from the primary sequence of the free peptide, cross-checked against PubChem. Salt forms, acetylation, amidation and counter-ions shift the real figure; lot-specific values are on the certificate.
No. It is a laboratory reference for unit conversions and solution maths. Eppix Labs products are supplied for in vitro and laboratory research purposes only, and the company provides no dosing, administration or protocol guidance.
Laboratory reference only. This calculator performs standard unit conversions and solution arithmetic for research use. It does not constitute medical advice or administration guidance of any kind. All Eppix Labs products are supplied for in vitro and laboratory research purposes only and are not approved by Health Canada for any use in humans or animals.
Every lot’s measured content is on its certificate
Use the real number, not the label, in the calculator.
All products are supplied for in vitro and laboratory research purposes only.