Drybench Calc.
Serial dilution planner
Volumes per tube, the transfer and the stock to draw for a fold series, with pipetting flags below 2 µL and the DMSO at every point.
Serial dilution
A fold series from a top concentration, each point made in one tube and pipetted into replicate wells.
Convert units
This action changes the number and unit together, preserving the physical quantity. The unit menu above continues to assign a unit to the entered number.
Convert units
This action changes the number and unit together, preserving the physical quantity. The unit menu above continues to assign a unit to the entered number.
Convert units
This action changes the number and unit together, preserving the physical quantity. The unit menu above continues to assign a unit to the entered number.
Optional. What the stock concentration refers to, for example “free base, dissolved in DMSO”. Recorded with the plan; not used in the calculation and not checked. Not a formula weight or a conversion factor.
100 for a neat DMSO stock; 0 for an aqueous stock.
Used on the plate sheet, the template and in Assay
This calculation tracks the named carrier from the stock, assumes the diluent contributes none of it, and treats volumes as additive.
Dilution plan
- Stock to draw
- 2.25µL
- Draw 2.25 µL of stock and 1.273 mL of diluent in all.Serial dilution plan
- First tube
- 225µL
- Pipette in: 75 µL
| Point | Concentration (µM) | Tube volume (µL) | Pipette in (µL) | Diluent (µL) | DMSO (%) | For the wells (µL) |
|---|---|---|---|---|---|---|
| 1 | 100 | 225 | 2.25from the stock | 222.8 | 1 | 150 |
| 2 | 33.33 | 225 | 75 | 150 | 0.333 | 150 |
| 3 | 11.11 | 225 | 75 | 150 | 0.111 | 150 |
| 4 | 3.704 | 225 | 75 | 150 | 0.037 | 150 |
| 5 | 1.235 | 225 | 75 | 150 | 0.0123 | 150 |
| 6 | 0.4115 | 225 | 75 | 150 | 0.00412 | 150 |
| 7 | 0.1372 | 225 | 75 | 150 | 0.00137 | 150 |
| 8 | 0.04572 | 225 | 75 | 150 | 0.000457 | 150 |
Point 1: 100 µM
Pipette in 2.25 µL from the stock, diluent 222.8 µL, DMSO 1 %
Point 2: 33.33 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.333 %
Point 3: 11.11 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.111 %
Point 4: 3.704 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.037 %
Point 5: 1.235 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.0123 %
Point 6: 0.4115 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.00412 %
Point 7: 0.1372 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.00137 %
Point 8: 0.04572 µM
Pipette in 75 µL from the tube before, diluent 150 µL, DMSO 0.000457 %
Point 1 is pipetted from the stock; each later point from the tube before.
The last tube is made like the others and keeps 75 µL over after its wells (serial dilution 2.0.0).
Bench flags
Pipetting volume
No point pipettes below the 2 µL bench rule.
Solvent carried over
- Point 1 carries 1.00 percent solvent, above the 0.5 percent rule of thumb for cells.Pipette in
Open in the bench sheetThe bench sheet carries these inputs and offers the other calculators.
Worked example
- A 3-fold series from 100 µM, 8 points, triplicate 50 µL wells: each tube holds 3 × 50 µL × 3/(3 − 1) = 225 µL before passing 75 µL on; the last tube is made the same way and keeps 75 µL over after its wells (serial dilution 2.0.0).
- From a 10 mM stock in neat DMSO the top tube takes 2.25 µL of stock, so the top point carries 1 percent DMSO and point 2 carries 0.33 percent: the first is flagged above the 0.5 percent rule of thumb.
- A transfer below 2 µL is flagged on the tube that receives it; make a larger tube or an intermediate dilution.
Method
- Serial dilution plan. src/lib/dilution/serial.ts 2.0.02.0.0 makes the last tube like the others; 1.0.0 gave the last point C/(f − 1) instead of C/f. Checked against exact rational arithmetic (Python 3.13.16 fractions) on 10 cases to nine significant figures, each step exactly the fold (10 October 2026).
- Transfers below 2 µL flagged. Bench convention set by the CSO, 6 October 2026; no external citation read.
- Final percent DMSO across a series. src/lib/dilution/dmso.ts 1.0.0Checked against Python's exact rational arithmetic (fractions.Fraction) to nine significant figures on 31 fixtures (6 October 2026).
Limits
- For research and education only, and not medical advice: the stock, dilution and buffer calculations here are not for dosing or clinical preparation.
- The 2 µL pipetting flag and the 0.5 percent DMSO flag are bench rules of thumb, not instrument specifications.
- The serial-dilution planner assumes each tube is made in one step from the tube before it and that the diluent carries no solvent of its own. Every tube, the last included, is made to the same volume with the same transfer, so the last keeps one transfer's volume over. Serial dilution 1.0.0: last point under-diluted by f/(f − 1); any plan printed from 1.0.0 is affected.