Peptide solution concentration calculator

A concentration calculator converts the mass of a reagent into concentration and volume in seconds. Below you will find the formulas behind the results, a table of worked laboratory examples and the handling practices that keep your solutions reliable.

The core formula

Concentration follows a simple relationship:

Quantity	Formula	Unit
Concentration	mass ÷ solvent volume	mg/ml
Conversion	1 mg/ml = 1 µg/µl	µg/µl
Portion volume	amount per portion ÷ concentration	µl
Portions per vial	vial mass ÷ amount per portion	pcs

Why mg/ml equals µg/µl

A milligram is 1000 micrograms and a millilitre is 1000 microlitres. Both units scale by the same factor, so the numerical value of the concentration stays the same when you switch from mg/ml to µg/µl. One number is enough for pipetting.

Worked laboratory examples

The table shows results for a 100 µg portion, a common quantity in solution preparation exercises.

Vial mass	Solvent	Concentration	Volume for 100 µg	Portions of 100 µg
5 mg	1 ml	5 mg/ml (5 µg/µl)	20 µl	50
5 mg	2 ml	2.5 mg/ml (2.5 µg/µl)	40 µl	50
5 mg	2.5 ml	2 mg/ml (2 µg/µl)	50 µl	50
10 mg	2 ml	5 mg/ml (5 µg/µl)	20 µl	100
10 mg	5 ml	2 mg/ml (2 µg/µl)	50 µl	100
2 mg	1 ml	2 mg/ml (2 µg/µl)	50 µl	20

The more solvent you add, the lower the concentration and the larger the volume needed for the same mass. Always check the nominal values for your batch, as the exact content can differ slightly from the label.

Good laboratory practice

• Accurate pipetting. Use calibrated pipettes and tips matched to the volume you are measuring.
• Solvent down the side. Add the solvent slowly along the wall of the vial to protect the sample.
• Do not shake. Swirl gently or let the solution dissolve on its own.
• Aliquot. Divide the solution into small portions to limit freeze and thaw cycles.
• Label everything. Record the compound name, concentration, date and your initials on every tube.
• Store cold. Keep solutions at 2-8 °C and keep dry reagent as specified on its product page.

Research use only

Every compound in our shop is sold as a research reagent for laboratory use. The calculator and this article are aids for preparing solutions, not instructions for any other use. Read our research use only policy and choose bacteriostatic water as a diluent. Browse the full range in the shop, or find supporting materials in the lab supplies category.