REFERENCE
Botox dilution reference
How units, mL and syringe lines relate, each label’s preparation, a dilution chart, worked examples and common questions.
How units, mL and syringe lines relate
Toxin units measure the product, milliliters measure the liquid, and syringe lines measure volume. A U-100 insulin syringe numbers its lines in insulin units, and one insulin unit is 0.01 mL. So the 10 line on an insulin syringe is 0.1 mL of liquid, whatever that liquid holds.
How many toxin units that 0.1 mL holds depends on how much saline went into the vial. At the Botox Cosmetic label preparation, 100 units in 2.5 mL, the 10 line holds 4 units. If the same vial were mixed with 2 mL, a custom preparation, the 10 line would hold 5.
A dose often falls between printed lines. At the Dysport label preparation of 12 units per 0.1 mL, 10 units is 0.083 mL, which reads 8.33 on an insulin syringe. On a syringe with a line every unit, that is between the 8 and 9 lines: the 8 line holds 9.6 units and the 9 line holds 10.8. The calculator shows what each neighboring line holds rather than pointing to a spot between them.
Line spacing by syringe
| Syringe | Printed scale | Lines | Units per line at 4 units per 0.1 mL |
|---|---|---|---|
| 0.3 mL insulin | U-100 insulin units | Every half unit (0.005 mL) | 0.2 |
| 0.3 mL insulin | U-100 insulin units | Every unit (0.01 mL) | 0.4 |
| 0.5 mL insulin | U-100 insulin units | Every unit (0.01 mL) | 0.4 |
| 1 mL insulin | U-100 insulin units | Every 2 units (0.02 mL) | 0.8 |
| 1 mL luer slip | mL | Every 0.01 mL | 0.4 |
| 1 mL luer lock | mL | Every 0.01 mL | 0.4 |
The calculator does not include dead space in the syringe hub or needle, product left in the vial, or any clinical judgment about dose.
Reconstitution on each US label
Cosmetic preparations listed in each product’s current US prescribing information. Each label states that its units cannot be compared to or converted into another product’s units, so this page gives no conversion ratios.
| Product | Vial | Saline added | Units per 0.1 mL | Use within | Label |
|---|---|---|---|---|---|
| Botox Cosmetic | 50 units | 1.25 mL | 4 | 24 hours | Prescribing information |
| Botox Cosmetic | 100 units | 2.5 mL | 4 | 24 hours | Prescribing information |
| Dysport | 300 units | 2.5 mL | 12 | 24 hours | Prescribing information |
| Dysport | 300 units | 1.5 mL | 20 | 24 hours | Prescribing information |
| Xeomin | 50 units | 0.25 to 5 mL (label table) | 20 to 1 (1.25 mL gives 4) | 24 hours | Prescribing information |
| Xeomin | 100 units | 0.5 to 5 mL (label table) | 20 to 2 (2.5 mL gives 4) | 24 hours | Prescribing information |
| Jeuveau | 100 units | 2.5 mL | 4 | 24 hours | Prescribing information |
| Daxxify | 50 units | 0.6 mL | 8* | 72 hours | Prescribing information |
| Daxxify | 100 units | 1.2 mL | 8* | 72 hours | Prescribing information |
| Letybo | 50 units | 1.25 mL | 4 | 24 hours | Prescribing information |
| Letybo | 100 units | 2.5 mL | 4 | 24 hours | Prescribing information |
* The Daxxify label states 8 units per 0.1 mL for this preparation. Dividing the vial by the saline gives 8.33. Labels read on DailyMed, the FDA label library, on October 30, 2026. Cosmetic preparations only; the labels list other volumes for therapeutic uses. Each label specifies preservative-free 0.9% sodium chloride and refrigeration at 2°C to 8°C after reconstitution.
Product notes: Dysport, Xeomin, Daxxify and the 4-unit labels
Dysport, 300-unit vial. The label lists 2.5 mL of saline for 12 units per 0.1 mL, or 1.5 mL for 20 units per 0.1 mL. Its glabellar line instructions describe a 10-unit aliquot as 0.08 mL at 12 units per 0.1 mL. Dividing gives 0.083 mL, between the 8 and 9 lines on an insulin syringe. At 20 units per 0.1 mL, 10 units is 0.05 mL. Open Dysport in the calculator
Xeomin, 50 and 100 units. The current label gives a dilution table instead of one cosmetic volume: 0.25 to 5 mL for the 50-unit vial and 0.5 to 5 mL for the 100-unit vial. Each row is a label preparation in the calculator. 1.25 mL in a 50-unit vial or 2.5 mL in a 100-unit vial gives 4 units per 0.1 mL. Open Xeomin in the calculator
Daxxify. The label lists 0.6 mL of saline for the 50-unit vial and 1.2 mL for the 100-unit vial, and states the result as 8 units per 0.1 mL. Dividing the vial by the saline gives 8.33 units per 0.1 mL. The calculator uses the division and shows the label’s figure beside every Daxxify result. The label allows use within 72 hours of reconstitution, compared with 24 hours for the other products here. Open Daxxify in the calculator
Botox Cosmetic, Jeuveau and Letybo. Each label lists 2.5 mL of saline per 100 units, and the Botox Cosmetic and Letybo labels list 1.25 mL per 50 units. Both give 4 units per 0.1 mL. Use within 24 hours of reconstitution. Open Botox Cosmetic in the calculator
Botox dilution chart: 100-unit and 50-unit vials
The Botox Cosmetic label preparation is 2.5 mL of saline in a 100-unit vial or 1.25 mL in a 50-unit vial, which gives 4 units per 0.1 mL. The other rows are arithmetic for comparison, not label preparations.
Show the full chart: 10 saline volumes for 100-unit and 50-unit vials
| Vial and saline | Units per mL | Units per 0.1 mL | Source |
|---|---|---|---|
| 100 units + 1 mL | 100 | 10 | Arithmetic only, not a label preparation |
| 100 units + 2 mL | 50 | 5 | Arithmetic only, not a label preparation |
| 100 units + 2.5 mL | 40 | 4 | Botox Cosmetic label preparation |
| 100 units + 3 mL | 33.33 | 3.33 | Arithmetic only, not a label preparation |
| 100 units + 4 mL | 25 | 2.5 | Arithmetic only, not a label preparation |
| 50 units + 0.5 mL | 100 | 10 | Arithmetic only, not a label preparation |
| 50 units + 1 mL | 50 | 5 | Arithmetic only, not a label preparation |
| 50 units + 1.25 mL | 40 | 4 | Botox Cosmetic label preparation |
| 50 units + 1.5 mL | 33.33 | 3.33 | Arithmetic only, not a label preparation |
| 50 units + 2 mL | 25 | 2.5 | Arithmetic only, not a label preparation |
Where common amounts sit at 4 units per 0.1 mL
At 4 units per 0.1 mL, which is 40 units per mL, the volume is the units divided by 40, and the insulin syringe reading is that volume times 100.
| Units | Volume | U-100 insulin syringe reading |
|---|---|---|
| 2 | 0.05 mL | 5 |
| 4 | 0.1 mL | 10 |
| 5 | 0.125 mL | 12.5 |
| 10 | 0.25 mL | 25 |
| 20 | 0.5 mL | 50 |
12.5 is a printed line only on syringes marked every half unit. Odd numbers fall between lines on 1 mL insulin syringes, which are marked every 2 units. 20 units (0.5 mL) needs a 0.5 mL or 1 mL syringe.
Worked examples
Each example follows the same three steps: strength, volume, then the reading on the syringe.
Botox Cosmetic, 4 units: on the 10 line
100-unit vial with 2.5 mL saline (label preparation). 0.3 mL insulin syringe with a line every unit.
- 100 ÷ 2.5 = 40 units per mL, or 4 units per 0.1 mL
- 4 ÷ 40 = 0.1 mL
- 0.1 × 100 = 10
On the 10 line. Open this example
Dysport, 10 units: between the 8 and 9 lines
300-unit vial with 2.5 mL saline (label preparation). 0.3 mL insulin syringe with a line every unit.
- 300 ÷ 2.5 = 120 units per mL, or 12 units per 0.1 mL
- 10 ÷ 120 = 0.0833 mL
- 0.0833 × 100 = 8.33
Between the 8 and 9 lines. The 8 line holds 9.6 units and the 9 line holds 10.8. The label describes this aliquot as 0.08 mL. Open this example
Custom preparation, Botox Cosmetic with 2 mL: on the 20 line
100-unit vial with 2 mL saline. The label does not list 2 mL, so this is a custom preparation. 0.5 mL insulin syringe, 10 units.
- 100 ÷ 2 = 50 units per mL, or 5 units per 0.1 mL
- 10 ÷ 50 = 0.2 mL
- 0.2 × 100 = 20
On the 20 line. The calculator labels this result a custom preparation. Open this example
Daxxify, 8 units: division and the label figure
100-unit vial with 1.2 mL saline (label preparation, stated as 8 units per 0.1 mL). 0.3 mL insulin syringe with a line every unit.
- 100 ÷ 1.2 = 83.33 units per mL, or 8.33 units per 0.1 mL
- 8 ÷ 83.33 = 0.096 mL
- 0.096 × 100 = 9.6
Between the 9 and 10 lines by division. The 9 line holds 7.5 units and the 10 line holds 8.33. By the label’s stated 8 units per 0.1 mL, 8 units is 0.1 mL, the 10 line. The calculator shows both. Follow the prescribing information where they differ. Open this example
Frequently asked questions
How do you calculate a Botox dilution?
Divide the vial’s units by the saline volume to get units per mL, then divide by 10 for units per 0.1 mL. For Botox Cosmetic, 100 units in 2.5 mL is 40 units per mL, or 4 units per 0.1 mL. To find the volume for an amount, divide the units by the units per mL: 10 units ÷ 40 = 0.25 mL.
How many units of Botox are in 0.1 mL?
It depends on the saline. At the Botox Cosmetic label preparation, 2.5 mL in a 100-unit vial or 1.25 mL in a 50-unit vial, 0.1 mL holds 4 units. With 2 mL in a 100-unit vial, a custom preparation, 0.1 mL holds 5 units.
How do I convert Botox units to mL?
Divide the units by the strength in units per mL. At 40 units per mL, 4 units is 0.1 mL, 10 units is 0.25 mL and 20 units is 0.5 mL. On a U-100 insulin syringe, multiply the mL by 100 to find the printed number, so 0.25 mL is the 25 line.
Are insulin syringe units the same as Botox units?
No. Insulin syringe numbers are U-100 insulin units, and each one is 0.01 mL of liquid. The toxin units in that liquid depend on the dilution: at 4 units per 0.1 mL, the 10 line holds 4 toxin units, not 10.
Which syringe shows small Botox amounts most precisely?
The one with the closest line spacing. A 0.3 mL insulin syringe marked every half unit has lines every 0.005 mL. The 0.3 mL and 0.5 mL insulin syringes marked every unit, and 1 mL luer syringes, have lines every 0.01 mL. A 1 mL insulin syringe has lines every 0.02 mL. At 4 units per 0.1 mL, those lines hold 0.2, 0.4 and 0.8 units.
What saline does the label specify?
Each of the six labels specifies sterile, preservative-free 0.9% Sodium Chloride Injection, USP. Bacteriostatic saline contains benzyl alcohol as a preservative, so it is not the diluent these labels name.
How long can reconstituted Botox, Dysport or Daxxify be used?
The labels say within 24 hours of reconstitution for Botox Cosmetic, Dysport, Xeomin, Jeuveau and Letybo, and within 72 hours for Daxxify, refrigerated at 2°C to 8°C during that time. Enter the time you mixed the vial in the calculator to add the use-by time to the printed card.
Are Dysport units the same as Botox units?
No. Each product’s label states that its units cannot be compared to or converted into another product’s units, so this calculator never converts between brands. Calculate each product with its own vial and label preparation.
How do you reconstitute a 50-unit vial of Botox Cosmetic?
The Botox Cosmetic label lists 1.25 mL of preservative-free 0.9% saline for the 50-unit vial. That gives 4 units per 0.1 mL, the same strength as 2.5 mL in the 100-unit vial. Follow the label’s preparation steps for technique.
Does adding more saline change the dose?
No. The units in the vial stay the same. More saline spreads them through more liquid, so each 0.1 mL holds fewer units and the same dose takes more volume. 100 units in 2.5 mL gives 4 units per 0.1 mL; in 4 mL, a custom preparation, it gives 2.5.
How much saline goes in a 300-unit vial of Dysport?
The Dysport label lists 2.5 mL for 12 units per 0.1 mL, or 1.5 mL for 20 units per 0.1 mL. At those strengths, 10 units is 0.083 mL or 0.05 mL.
How much saline do you add to Daxxify?
The Daxxify label lists 0.6 mL for the 50-unit vial and 1.2 mL for the 100-unit vial, and states both as 8 units per 0.1 mL. Simple division gives 8.33, and the calculator shows both figures.
About this calculator
Sources, calculation method and what it leaves out
Sources. Each product’s current US prescribing information on DailyMed, the FDA label library, checked October 30, 2026. Label versions are checked every month, and a changed label is reread before the calculator changes.
How results are calculated. Strength is the vial’s units divided by the saline volume. Every result uses that division at full precision and is rounded only for display. Where a label states a different figure, as Daxxify’s does, the label figure is shown beside the result.
What it leaves out. Doses, injection sites, dead space in the syringe hub or needle, product left in the vial and any conversion between products.