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Serial Dilution Calculator (Volumes and Concentration per Tube)

Enter the starting concentration, dilution factor, number of steps and the volume you need per tube, and get the transfer volume, diluent volume and a tube-by-tube concentration table.

Inputs

Type 10 or 1:10, both mean 1 part in 10 parts total

Results

Transfer into each tube
100 μL
Diluent per tube
900 μL
Starting solution used
100 μL
Total diluent
4.5 mL

Tubes 1 to 4 keep 900 μL after passing on their transfer; tube 5 keeps 1 mL.

Tube-by-tube table

TubeTotal dilutionConcentration (mg/mL)TransferDiluent
11:100.1100 μLfrom start900 μL
21:1000.01100 μL900 μL
31:1,0000.001100 μL900 μL
41:10,0001×10⁻⁴100 μL900 μL
51:100,0001×10⁻⁵100 μL900 μL

Formula

Transfer (mL) = Final volume per tube ÷ Dilution factor

Diluent (mL) = Final volume per tube − Transfer

Conc. of tube k = Starting conc. ÷ Dilution factor^k

Tip: 1:10 means 1 part in 10 parts total (dilution factor 10). With the 10% extra option, the final volume is multiplied by 1.1 first. Every tube except the last loses one transfer volume when you pass it on to the next tube.

You got this step right, but a whole experiment has dozens of linked parameters. Change one dilution factor and everything downstream has to be recalculated. In Vara the parameters of your whole experiment are connected, so changing one recalculates the rest automatically. Manage 3 experiments for free.

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FAQ

How do I make a 10-fold serial dilution with 5 tubes of 1 mL each?+
Transfer 1 mL ÷ 10 = 100 μL into each tube and add 1 mL − 100 μL = 900 μL of diluent. Fill 5 tubes with 900 μL of diluent, add 100 μL of your starting solution to tube 1 and mix, then move 100 μL from tube 1 to tube 2, and so on through tube 5. Tube 5 is 1/10⁵ of the start (1:100,000). Tubes 1 to 4 end up with 900 μL after their transfer and tube 5 keeps 1 mL, so discard 100 μL from tube 5 if you need equal volumes.
Does 1:10 mean 1 part plus 10 parts, or 1 part in 10 parts total?+
This calculator reads 1:10 as 1 part sample in 10 parts total, a dilution factor of 10: 1 part sample plus 9 parts diluent. Some protocols write 1:10 for 1 part sample plus 10 parts diluent, which is really an 11-fold dilution, so enter 11 as the factor. When in doubt, check the volumes in the protocol: 100 μL plus 900 μL is 10-fold, 100 μL plus 1 mL is 11-fold.
How do I make a 2-fold standard curve with 8 points of 100 μL from 1000 ng/mL?+
Transfer 100 μL ÷ 2 = 50 μL into each tube and add 50 μL of diluent. The 8 tubes come out at 500, 250, 125, 62.5, 31.25, 15.63, 7.813 and 3.906 ng/mL. If the starting solution is also the top point of your curve, keep it aside and do not count it among the 8 steps.
What does the 10% extra option do?+
It makes each tube 1.1 times the final volume, so you have room for liquid left in tips and on tube walls. For a 10-fold dilution at 1 mL per tube you transfer 110 μL and add 990 μL, giving 1.1 mL. After passing 110 μL on, 990 μL is left, close to the 1 mL you planned to use.
The transfer volume is too small to pipette. What should I do?+
Below 1 μL, pipetting error gets large. A 1:1000 step at 100 μL per tube needs only 0.1 μL. Either increase the final volume per tube, or split the 1:1000 step into three 1:10 steps of 10 μL plus 90 μL each. The final concentration is the same.
How is the concentration of each tube calculated, and which tube should I plate?+
Tube k = starting concentration ÷ dilution factor to the power k. Starting at 1×10⁸ CFU/mL with 10-fold steps, tube 5 is 1×10⁸ ÷ 10⁵ = 1000 CFU/mL, so plating 100 μL gives about 100 colonies, inside the usual countable range of 30 to 300.

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