Guide 2
IV Cannula and Needle Gauge Chart, Colour Coded
For peripheral IV cannulas that follow the ISO colour-coding convention, the hub colour indicates the cannula size/gauge. Orange (14G) and grey (16G) are the wide bores for rapid, high-volume flow. Green (18G) and pink (20G) handle routine adult therapy. Blue (22G), yellow (24G), and violet (26G) suit children, older patients, and fragile veins.
As a general rule, the higher the gauge number, the smaller the cannula diameter; potential flow is generally lower, but actual flow depends on catheter length, design, fluid properties and pressure.
IV Cannula Size and Colour Chart
The colour on an IV cannula hub corresponds to its gauge, making it easier to identify different sizes in clinical settings. Flow rates are approximate and can vary depending on the manufacturer and product specifications.
| Colour | Gauge | Approx. flow rate | Typical use |
|---|---|---|---|
| Orange | 14G | ~240 mL/min | Trauma, rapid fluid delivery, theatre |
| Grey | 16G | ~180 mL/min | Surgery, high-volume fluids |
| Green | 18G | ~90 mL/min | Blood products, routine adult infusions |
| Pink | 20G | ~60 mL/min | Routine adult infusions, most IV medications |
| Blue | 22G | ~36 mL/min | Small or fragile veins, children, older patients |
| Yellow | 24G | ~20 mL/min | Neonates, children, very fragile veins |
| Violet | 26G | ~13 mL/min | Neonates, extremely fragile veins |
Colours generally follow internationally recognized conventions for peripheral IV cannulas. Flow rates are approximate and may differ between manufacturers, so check the product data sheet for the specific cannula being used.
The simple rule to remember
The higher the gauge number, the thinner the cannula and the slower the potential flow rate. A 24G is smaller than an 18G.
What Do the Cannula Colours Mean?
The colour on the hub is shorthand for the gauge, making it easier to identify the cannula size at a glance in clinical settings. Pink and green are used for routine IV therapy for everyday adult care. Orange and grey may be chosen for higher flow rates required during trauma, surgery, or other situations when rapid fluid administration is needed. The smaller blue, yellow, and violet sizes may be appropriate for patients with small or fragile veins.
Colour coding helps identify the size, but the appropriate cannula should always be selected according to the patient's needs and the therapy being administered.
What Does Gauge Actually Measure?
Gauge is a conventional size designation associated with needle/cannula diameter. A higher gauge number corresponds to a smaller diameter. Larger-bore devices generally permit higher flow than smaller-bore devices, but actual flow also depends on catheter length and design, fluid properties, tubing and pressure.
How Do You Choose the Right Cannula Size?
Three things generally influence cannula selection: the therapy being given, the vein, and the patient. Consider how quickly the fluid or medication needs to be administered and the condition of the available vein. A commonly recommended principle is to select the smallest cannula that can safely and effectively deliver the required therapy, while considering vein condition, patient factors and local protocol. Larger bores may be selected when higher flow rates are required.
Clinical note:This chart is a reference, not clinical advice. Cannula selection and insertion should follow your facility's protocol and the judgement of the treating healthcare professional.
Hypodermic Needle Gauge Chart
| Colour | Gauge | Common length | Typical use |
|---|---|---|---|
| Pink | 18G | 38 mm | Drawing up and reconstituting medication |
| Black | 22G | 32 mm | Intramuscular injection, depending on the medication |
| Blue | 23G | 25 mm | Intramuscular and subcutaneous injection |
| Grey/Brown | 26G | 10 to 13 mm | Subcutaneous and intradermal injection |
Hypodermic needle colours are a separate convention from the IV cannula colours above. The gauge scale works in the same inverse way, but colour coding can vary between standards and manufacturers. Always check the product packaging and manufacturer's specifications.
What Size Are Insulin Pen Needles?
Pen needles are shorter and finer again, sized by length as well as gauge. The common lengths are 4, 5, 6, and 8 mm. Shorter pen needles, such as 4 mm and 5 mm options, are widely used and may help reduce the risk of an injection reaching muscle. The appropriate needle length should be selected according to the individual and applicable clinical guidance.
Where to Buy Cannulas and Needles in Australia
Joya Medical Supplies stocks colour-coded IV cannulas from 14G to 26G, along with hypodermic needles in a range of gauges and sizes. Products are available in singles and cartons, with Australia-wide delivery. Product pages provide information about specifications, pack sizes, and purchasing requirements.
FAQ
- What size is a pink cannula?
- A pink cannula is 20 gauge (20G), with an approximate flow rate of 60 mL per minute. The actual flow rate can vary between manufacturers and products. It is one of the most common sizes for routine adult infusions.
- Which cannula has the fastest flow rate?
- The orange 14G has the largest bore in this chart at approximately 240 mL/min, followed by the grey 16G. These wide bores may be selected for trauma, rapid fluid administration, and other situations where higher flow is required.
- Is a higher gauge number bigger or smaller?
- Smaller. The scale runs backwards, so a 24G cannula is thinner and smaller in diameter than an 18G and generally provides a lower flow rate.
- What gauge needle is used for an intramuscular injection?
- A 22G or 23G needle is commonly used at 25 to 38 mm, though the right choice depends on the medication and factors such as the injection site and patient. Follow your clinical protocol.
- Can you buy syringes and needles over the counter in Australia?
- Supply and purchasing requirements can vary by product, supplier and jurisdiction. Check the individual product listing and applicable state or territory requirements, and seek pharmacist or healthcare advice if unsure.