Serial Dilution Calculator
Amplified Labs · Research calculations
Serial Dilution Calculator
This calculator works from a stock of known concentration. It has two modes. Serial mode plans an equal-factor dilution series and shows each step’s concentration, its cumulative dilution from stock, and the transfer, diluent, mixed and remaining volumes for every tube. Single mode solves C1V1 = C2V2 for one working solution and gives the stock volume and diluent needed to reach a target concentration. If you know only the milligrams printed on a vial, use the reconstitution calculator first to work out a stock concentration. To work out component concentrations in a blend, use the peptide blend calculator.
This tool is for planning laboratory research only. It performs arithmetic and does not give dosing, administration or medical guidance.
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Plan your dilution
Your dilution plan
Enter the values for the selected mode, or load an example, to see a dilution plan. Changing any input or switching modes clears the previous result.
Positive numbers can be entered in scientific notation, for example 2.5e-3. Very small concentrations are displayed in scientific notation and are never rounded to zero, so check the exponent when you copy a value. These figures are arithmetic results, and the concentration you actually achieve depends on how accurately you pipette and mix. The calculations run in your browser.
Reading the dilution table
The stock solution is step 0. Each row after it is a new tube made from the tube before it, and the step count includes only these new tubes. The cumulative column shows each tube’s total dilution relative to the stock. After n steps with factor F, that dilution is 1:F^n, so three ten-fold steps give 1:1000.
On this page, 1:x means 1 part in x parts total. A ten-fold step is therefore 1 part of the previous solution plus 9 parts of diluent, not 1 part plus 10 parts. Some protocols write the same step as a fraction, D = 0.1. This calculator always uses the fold factor F, which is greater than 1, and D = 1/F.
Mixed volume is the volume in a tube immediately after you combine the transfer and the diluent. The transfer into each tube is the mixed volume divided by F. It comes from the stock for tube 1 and from the previous tube for every later step. The diluent is the mixed volume minus the transfer.
Remaining volume is the amount left in a tube after its onward transfer. Every tube except the last gives up one transfer, so each of those tubes keeps the mixed volume minus the transfer. The last tube makes no onward transfer and keeps its full mixed volume. The plan does not discard any volume from the last tube to equalize volumes, so if your method needs equal volumes in every tube, plan for that separately.
The totals show the stock volume needed, which equals one transfer, and the total diluent, which equals the number of steps multiplied by the diluent per tube. These totals do not include dead volume, volume removed for assays or replicates, or pipetting losses.
Serial dilution formula and variables
For an equal-factor series, Cn = C0 / F^n. Here C0 is the stock concentration, F is the fold reduction per step (greater than 1), n is the step number counted from the stock at step 0, and Cn is the concentration in tube n. Written with the dilution fraction D = 1/F, the same relationship is Cn = C0 × D^n.
The volumes for each step follow from the mixed volume V. The transfer is t = V / F and the diluent is d = V − t. For a series of N tubes, the stock needed is t and the total diluent is N × d. Every tube from 1 to N − 1 keeps V − t, and tube N keeps V.
Single mode uses C1V1 = C2V2. C1 is the stock concentration, C2 is the target concentration, V2 is the final volume and V1 is the stock volume to add. Rearranged, V1 = C2 × V2 / C1, the diluent is V2 − V1, and the dilution factor is C1 / C2. The target must be greater than zero and no higher than the stock concentration. If the target equals the stock concentration, no diluent is needed.
Both concentrations must use the same unit, and the volumes are reported in the volume unit you choose. The formula does not convert between mass and molar units.
Method references include the AAT Bioquest serial dilution tool, the Carolina serial dilution handout and the GraphPad QuickCalcs molarity calculator.
Worked dilution examples
Three ten-fold dilution steps
This example starts with a 1,000 µg/mL stock and prepares three ten-fold steps with a mixed volume of 1,000 µL per tube. Each new tube receives 100 µL from the tube before it plus 900 µL of diluent. The concentration falls by a factor of 10 at each step, so the third tube is at 1:1000 of the stock, or 1 µg/mL. The series uses 100 µL of stock and 2,700 µL of diluent in total. Tubes 1 and 2 each keep 900 µL after their onward transfer, and the last tube keeps the full 1,000 µL.
| Tube | Concentration (µg/mL) | Transfer (µL) | Diluent (µL) | Mixed (µL) | Remaining (µL) |
|---|---|---|---|---|---|
| 1 | 100 | 100 | 900 | 1000 | 900 |
| 2 | 10 | 100 | 900 | 1000 | 900 |
| 3 | 1 | 100 | 900 | 1000 | 1000 |
Four two-fold dilution steps
Starting at 10 mg/mL, four two-fold steps give 5, 2.5, 1.25 and 0.625 mg/mL. The final tube is at 1:16 of the stock concentration.
Single stock-to-working dilution
This example dilutes a 5 mg/mL stock to 0.05 mg/mL in a final volume of 2 mL. The required stock volume is 0.05 × 2 ÷ 5 = 0.02 mL (20 µL), and the remaining 1.98 mL is diluent. This is a single 100-fold dilution.
What this calculator does not tell you
The results assume uniform, well-mixed solutions, volumes that add exactly, and no loss of the measured substance between tubes. The calculator does not account for dead volume, volume removed for assays, extra volume for replicates, or pipetting error, so add any margin your method requires. It also does not adjust for molecular weight, purity, activity units or labelled mass. The arithmetic cannot show whether a solvent or diluent is suitable, whether a material is soluble or stable at a given concentration, whether a solution is compatible with an assay, or what concentration was actually achieved. All results are for planning laboratory research and are not dosing or medical guidance.
Related Amplified Labs products and lot documentation
Amplified Labs offers BPC-157, GHK-Cu, Ipamorelin, KPV, TB-500 and Tesamorelin. Each card below links to the product listing and to its public certificate of analysis (COA) folder. Product links do not set a stock concentration. Enter the concentration established for your own solution. A COA applies only to the lot it identifies. Compare the lot shown on your label with the lot named in the document. These links provide documentation only and do not confirm that a particular shipped vial matches a listed lot.
BPC-157
View productView COA folderGHK-Cu
View productView COA folderIpamorelin
View productView COA folderKPV
View productView COA folderTB-500
View productView COA folderTesamorelin
View productView COA folderSerial dilution questions
How do I calculate a serial dilution?
Divide the stock concentration by the fold factor once for each step: Cn = C0 / F^n. Plan the volumes separately. Each tube receives a transfer of V / F from the tube before it, plus diluent equal to V minus the transfer, where V is the mixed volume per tube.
Does 1:10 mean one part stock plus ten parts diluent?
No. On this page, 1:10 means 1 part in 10 parts total, which is 1 part of the previous solution plus 9 parts of diluent. This corresponds to a fold factor F of 10, or a dilution fraction D of 0.1.
Does the starting stock count as step 1?
No. The stock is step 0, and the number of steps counts only the new diluted tubes. Three ten-fold steps produce tubes at 1:10, 1:100 and 1:1000 of the stock. Some other tools count the starting solution as a step, so check which convention your protocol uses.
How does a two-fold serial dilution work?
With F = 2, each tube holds half the concentration of the tube before it. Four two-fold steps from a 10 mg/mL stock give 5, 2.5, 1.25 and 0.625 mg/mL. Half of each tube’s mixed volume comes from the previous tube, and the other half is diluent.
Why is less volume left in the earlier tubes?
Each tube except the last gives up a transfer of V / F to make the next tube, so it keeps V minus that transfer. The last tube makes no onward transfer and keeps its full mixed volume. The calculation does not include dead volume or any volume you remove for assays.
How much stock do I need for a single working solution?
Use V1 = C2 × V2 / C1, with both concentrations in the same unit. For example, to make 2 mL at 0.05 mg/mL from a 5 mg/mL stock, you need 0.02 mL (20 µL) of stock plus 1.98 mL of diluent.
Can I switch between mg/mL and µM?
Not in this calculator. The unit selector changes the label on every concentration value but does not convert any of them. Converting between mass and molar units requires the compound’s molecular weight and a well-defined material.
Can I start from the mg printed on a vial?
Not directly. A labelled amount in mg is a mass, not a concentration. Use the reconstitution calculator with your final solution volume to work out a stock concentration, then enter that concentration here.
Does the result confirm solvent suitability or a matching COA?
No. The arithmetic does not choose a solvent or diluent and does not show solubility, stability or assay compatibility. Each COA link is documentation for the lot it identifies, so compare the lot on your label with the lot named in the document.
Make a label for your research record
Once you have a valid result, select Create a vial label to open the Peptide Label Maker with your values ready to check and edit.
Peptide COA Finder
Find an available original report by product or full lot, then compare the document details with your label.
