How to use it
- Set the volume of one finished reaction and how many you are setting up.
- Add the extra you want on top. A percentage scales with the batch; whole reactions suit a small run.
- List what goes into one reaction. Enter a volume directly, or a stock and final concentration and let the volume follow.
- Leave the water row as the one that fills the rest. It takes the reaction volume minus everything else.
- Read the batch column, which is what you pipette into the tube.
The arithmetic and what to watch
Each row is scaled from one reaction to the batch, and one row is left to make up the difference.
A volume from a stock and a final concentration
Only this pair stays right when the reaction volume changes, which is the reason to enter it rather than a volume.
- µL per reaction = final ÷ stock × reaction volume
The batch
The extra is applied once, to the number of reactions, so every row keeps its share of the mix.
- reactions made = reactions × (1 + extra ÷ 100)
- batch µL = µL per reaction × reactions made
The row that fills the rest
- water = reaction volume − everything else
Worth knowing
- The extra exists because a pipette leaves some behind in every tip and every tube. Ten percent is a common starting point; a run of very few reactions is better served by adding whole reactions.
- A stock and final concentration beat a typed volume when both are present. Nothing is hidden by that: the volume column shows what came out.
- Template is listed here as an ordinary row. On a plate it is entered per well instead, which is the difference between this tool and the PCR plate designer.
- This tool and the PCR plate designer share one implementation of the recipe, so the two cannot disagree about a number.
Questions
Enough to cover what the pipette leaves behind, which depends on how many transfers the batch takes rather than on a rule. Ten percent is where most protocols start. For a handful of reactions, adding one or two whole reactions is easier to reason about than a percentage.
Because it is the only row whose volume is not a decision. It is the reaction volume minus everything else, so it changes whenever any other row does.
Yes. Give the stock and the final concentration in the same units and the volume follows from the reaction volume. That is the entry worth making, because it stays correct if you change the reaction volume later.
Only in how the reaction count arrives. The plate designer counts wells you have laid out; this one takes the number. The recipe arithmetic underneath is the same code, so both give the same answer for the same mix.
Then there is no room for the water row and nothing can be made as written. Either the reaction volume is too small or one of the volumes is too large.
Often used together
Open →
PCR Plate Designer & Master Mix Calculator
Lay out a 96-well plate and get the mix volumes that go with it, on one printable page.
Open →
qPCR Amplification Efficiency Calculator
Calculates amplification efficiency (%) and the per-cycle factor from a standard curve slope.
Open →
Oligo Resuspension Calculator
Paste a whole delivery list and get the buffer volume for every tube at once, with clipboard and Excel export.