Lab calculator
Reconstitution calculator
Find the concentration of a reconstituted vial, the volume that holds a set mass, and how many equal aliquots one vial makes. Or run it backwards to find the diluent volume for a target concentration.
- Mass, volume and concentration only
- Every formula shown
- Nothing leaves your browser
Calculator
Results
Concentration 10 milligrams per millilitre. 100 microlitres per aliquot. 10 whole aliquots.
Concentration
10mg/mL
Volume per aliquot
100µL
Aliquots per vial
10
Left over
None
The working
- C = m / V= 10 mg / 1 mL = 10 mg/mL
- Valiquot = a / C= 1 mg / 10 mg/mL = 0.1 mL (100 µL)
- n = ⌊m / a⌋= ⌊10 mg / 1 mg⌋ = 10
- Left over = V − n × Valiquot= 1 mL − 10 × 0.1 mL = 0 mL
- m
- mass in the vial
- V
- diluent volume
- a
- mass per aliquot
- C
- concentration
- n
- whole aliquots
Results are arithmetic only. Check them against your own protocol, measurements and equipment before you rely on them.
Everything on Vialwise concerns research-grade material sold for laboratory and analytical use only. It is not a registered medicine, is not supplied for human or veterinary use, and nothing here is medical advice.
How the numbers work
The arithmetic, shown in full
Nothing here is hidden or approximated. These are the same formulas the calculator uses, and the worked example runs through the same code.
C = m / V
Concentration is mass over volume
Dissolve a known mass in a known volume and every part of the solution carries the same concentration. That single number is what lets you measure out a set mass later by volume alone.
Valiquot = a / C
Volume per aliquot follows from it
Divide the mass you want in each aliquot by the concentration. Keep the scales consistent: the calculator converts µg to mg before dividing, so you don’t have to.
n = ⌊m / a⌋
Only whole aliquots count
The number of aliquots is rounded down, because a partial aliquot doesn’t hold the full mass. Whatever remains is reported separately, with the mass it contains.
1 mg/mL = 1 µg/µL
Two scales, one number
A milligram is 1,000 micrograms and a millilitre is 1,000 microlitres. Both sides of the ratio scale by the same factor, so mg/mL and µg/µL are always identical.
Worked example
A 10 mg vial made up to 1 mL, split into 1 mg aliquots
The example the calculator loads when you open it.
- 1
ConcentrationC = m / V
10 mg / 1 mL = 10 mg/mL
That is also 10 µg/µL: the same number in both scales.
- 2
Volume per aliquotValiquot = a / C
1 mg / 10 mg/mL = 0.1 mL
100 µL of the solution holds 1 mg.
- 3
Whole aliquotsn = ⌊m / a⌋
⌊10 mg / 1 mg⌋ = ⌊10⌋ = 10
Only whole aliquots are counted: a part aliquot doesn’t hold the full mass.
- 4
Left overV − n × Valiquot
1 mL − 10 × 0.1 mL = 0 mL
Nothing remains: 10 aliquots of 100 µL use the whole 1 mL.
At the bench
What the arithmetic can’t check for you
The calculator is only as good as the numbers it is given. Four habits keep them honest.
Use the measured content
The mass on a label is nominal. If the batch’s certificate of analysis reports a measured content, for example 10.2 mg against a 10 mg label, enter that figure instead. It was measured on the tested sample, so for other vials from the same batch it is an estimate.
Purity versus peptide contentRecord the diluent
Record the diluent: sterile water, a buffer or whatever your protocol names. Solution stability depends on the diluent and the compound; see the storage guide.
Storing lyophilised peptidesLabel what you made
Write the compound, concentration, diluent and date on the vial. A concentration you can’t read back later is one you end up recalculating from memory.
Store it for the form it’s in
Lyophilised powder and a solution keep differently. The storage guide covers temperature, light and moisture for both.
Storing lyophilised peptides
Questions
Details worth knowing
Does the calculator depend on which compound is in the vial?
No. It only needs a mass and a volume, so the arithmetic is the same for any lyophilised material. It doesn’t know about solubility or stability, which is why the bench notes above matter.
Does the powder add to the volume?
The calculator assumes the solid dissolves completely and adds no volume of its own. For a few milligrams in a millilitre or more of diluent that is a very small error, but it grows as the mass rises relative to the volume.
Why do my aliquots not use the whole vial?
Aliquots are counted in whole numbers. If the vial doesn’t divide exactly, the remainder is shown as the leftover, in µL and in the mass it holds. Adjust the diluent volume or the mass per aliquot if you want it to divide evenly.
What precision are the results shown at?
Around four significant figures for values of 1 or more and three below 1, with trailing zeros dropped. That is finer than most pipettes can deliver, so round to what your equipment can measure.
Is anything I type saved or sent?
No. The calculator runs entirely in your browser. Nothing is stored, and nothing is sent to Vialwise or anyone else.
Check your input
Start from a figure you can check
The arithmetic is only as good as the mass you enter, which is why it helps to start from a lab report you can open yourself. The Test results page links reports that open on the lab’s own site, and the guide shows how to match one to its vial, line by line.