# U-100 vs U-40 Syringes: What the Numbers Mean - facts

Canonical page: https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes
Type: Lab article

## TL;DR

U-100 syringes come in 0.3, 0.5, and 1 mL sizes — not all hold 1 mL. Here's how U-100 and U-40 unit scales differ, unit by unit, with a free conversion table.

## Facts Index

| Fact ID | Category | Entity | Attribute | Value | Source | Evidence |
|---|---|---|---|---|---|---|
| u100-vs-u40-syringes:title | identity | U-100 vs U-40 Syringes: What the Numbers Mean | title | U-100 vs U-40 Syringes: What the Numbers Mean | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:published | identity | U-100 vs U-40 Syringes: What the Numbers Mean | published | 2026-07-10 | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:last-reviewed | identity | U-100 vs U-40 Syringes: What the Numbers Mean | last reviewed | 2026-10-05 | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:author | identity | U-100 vs U-40 Syringes: What the Numbers Mean | author | Preppin' Peppers Editorial Team | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:topics | identity | U-100 vs U-40 Syringes: What the Numbers Mean | topics | Equipment and consumables, research | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:summary | content | U-100 vs U-40 Syringes: What the Numbers Mean | summary | U-100 syringes come in 0.3, 0.5, and 1 mL sizes — not all hold 1 mL. Here's how U-100 and U-40 unit scales differ, unit by unit, with a free conversion table. | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-1 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | What the Numbers Mean | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-2 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | U-100 vs U-40 Syringes: What the Numbers Mean | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-3 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | What the Number Actually Refers To | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-4 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | The Units-per-Milliliter Math | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-5 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | How the Barrels Are Marked | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-6 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | Why Mixing the Scales Produces a Fixed Error | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-7 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | Quick Reference | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-8 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | Related reading | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-9 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | Tools and supplies | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:section-11 | content | U-100 vs U-40 Syringes: What the Numbers Mean | section | What the research community gets wrong about U-100 and U-40 syringes | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes |
| u100-vs-u40-syringes:product-gansulin-metal-peptide-pen | products | U-100 vs U-40 Syringes: What the Numbers Mean | references product | Gansulin Pen · Reusable Click-Dial, 3 ml (1-60 Units) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/products/gansulin-metal-peptide-pen |
| u100-vs-u40-syringes:product-gansulin-3ml-cartridge | products | U-100 vs U-40 Syringes: What the Numbers Mean | references product | Gansulin-Compatible 3 ml Glass Cartridge for Pens (10-Pack) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.preppinpeppers.com/products/gansulin-3ml-cartridge |
| u100-vs-u40-syringes:source-dailymed-nlm-nih-gov | source | U-100 vs U-40 Syringes: What the Numbers Mean | cites | Insulin Aspart (NovoLog) injection label , FDA/DailyMed, states "100 units/mL (U-100)" - dailymed.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bee5b358-c863-420b-be73-ced2e920c499 |
| u100-vs-u40-syringes:source-www-ema-europa-eu | source | U-100 vs U-40 Syringes: What the Numbers Mean | cites | European Medicines Agency , Medication errors: risk minimisation for high-strength insulin above the standard 100 units/ml concentration - www.ema.europa.eu | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://www.ema.europa.eu/en/human-regulatory-overview/post-authorisation/pharmacovigilance-post-authorisation/medication-errors |
| u100-vs-u40-syringes:source-pubmed-ncbi-nlm-nih-gov | source | U-100 vs U-40 Syringes: What the Numbers Mean | cites | Dunne and Whitaker, Anaesthesia 2016: Prefilled insulin syringes - pubmed.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://pubmed.ncbi.nlm.nih.gov/26864010/ |
| u100-vs-u40-syringes:source-pubmed-ncbi-nlm-nih-gov-2 | source | U-100 vs U-40 Syringes: What the Numbers Mean | cites | Bosquet et al., Diabetes Care 1986: Insulin syringe reuse - pubmed.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/u100-vs-u40-syringes) | https://pubmed.ncbi.nlm.nih.gov/3525061/ |

## FAQ

### What does U-100 mean on a syringe?

U-100 means the barrel's printed scale divides 1 mL into 100 equal unit marks, so each mark equals 0.01 mL. It describes the scale's concentration reference, not the syringe's physical size or needle length.

### What is the difference between U-100 and U-40 syringes?

U-100 has 100 unit marks per mL (1 unit = 0.01 mL); U-40 has 40 marks per mL (1 unit = 0.025 mL). The scales differ by a factor of 2.5. The syringe scale must match the solution being measured to avoid a 2.5× reading error.

### How do you convert U-100 unit marks to milliliters?

Divide the unit number by 100. Example: 25 units on a U-100 syringe equals 0.25 mL (25 ÷ 100). For U-40, divide by 40: 10 units equals 0.25 mL (10 ÷ 40). Both follow directly from the units-per-mL definition of each scale.

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