Understanding Nutrition Diet: What is the portion size for IDDSI?

October 19, 2025 •

4 min read

According to the International Dysphagia Diet Standardisation Initiative (IDDSI), standardizing food texture reduces choking risk by up to 60% in patients with swallowing difficulties. This critical safety standard explains what is the portion size for IDDSI—not in terms of total volume, but precise particle dimensions for safe consumption.

Quick Summary

The IDDSI framework specifies particular particle sizes for texture-modified foods (Levels 5, 6) rather than conventional food portion sizes. Adherence to these safety-critical dimensions prevents choking and aspiration. Different IDDSI levels have distinct size requirements for both adults and children, which are verifiable using simple testing methods.

Key Points

Particle Size is Key: IDDSI defines food particle dimensions for safety, not total serving size, distinguishing it from conventional portion control.
Level 6 (Soft & Bite-Sized): For adults, food pieces must be no larger than 1.5cm x 1.5cm, approximately the size of a thumbnail.
Level 5 (Minced & Moist): For adults, food lumps must be finely minced, no bigger than 4mm in width and 15mm in length.
Simple Testing Tools: Standard kitchen items like a fork can be used to check particle size and softness for food levels 5 and 6.
Child-Specific Sizing: Particle size limits are reduced for young children under 5 to ensure their safety, with smaller dimensions for levels 5 and 6.
Safety Prevents Malnutrition: By reducing choking and aspiration risk, IDDSI helps ensure consistent and safe food intake, which is critical for preventing malnutrition in dysphagia patients.
Smooth Foods Have No Particles: Levels 3 (Liquidised) and 4 (Pureed) require a smooth, lump-free texture, so particle size is not applicable.

The IDDSI Framework: A Global Standard for Safe Swallowing

The International Dysphagia Diet Standardisation Initiative (IDDSI) provides a global framework for describing texture-modified foods and thickened liquids for individuals with dysphagia, or swallowing difficulties. Before IDDSI was widely adopted, terminology varied significantly, causing confusion and compromising patient safety. The framework's standardized approach categorizes foods and liquids into a continuum of eight levels (0–7), using numbers, labels, and color codes to identify them. The primary goal of this system is to enhance safety, reduce health complications like choking and aspiration, and ultimately improve the quality of care.

Particle Size vs. Total Portion Size: Clarifying the IDDSI Standard

When people ask what is the portion size for IDDSI, they often confuse conventional portion control with the specific particle size requirements defined by the framework. In a standard diet, portion size refers to the total amount of food served (e.g., one cup of rice, 4 ounces of chicken). For dysphagia patients on an IDDSI diet, the total serving size still depends on their individual nutritional needs, as determined by a healthcare professional like a dietitian. However, the framework adds a critical layer of safety by dictating the maximum size of individual food pieces for certain levels. These particle size limits are designed to reduce the risk of choking and are a central component of the IDDSI guidelines.

Defining Particle Size Across Food Levels

While all IDDSI levels are crucial, specific food levels have strict particle size definitions. The following are the most relevant food levels where particle size is a defining characteristic:

Level 5: Minced and Moist

At this level, food is soft, moist, and cohesive, with small, soft lumps. Biting is not required, but some tongue force is needed to mash and move the bolus. The particle size is specifically defined to minimize choking risks.

Adults: Lumps are no larger than 4mm in width and 15mm in length. A standard fork can be used as a simple testing tool, as the space between the prongs is approximately 4mm.
Children: Lumps should not exceed 2mm in width and 8mm in length.

Level 6: Soft and Bite-Sized

This level is for individuals who can chew, but may have difficulty biting off larger pieces of food. Foods should be soft, tender, and moist, with no separate thin liquid. The pieces are small enough to be swallowed safely with some chewing.

Adults: Food pieces must be no larger than 1.5cm x 1.5cm (approx. the size of a thumbnail).
Children (under 5 years): The target size is reduced to half, at 0.8cm x 0.8cm.

Level 7: Regular (Easy to Chew)

This is a higher level for individuals with effective chewing and swallowing skills. While there are no specific particle size restrictions, foods must be developmentally and age-appropriate and easy to chew. Tough, hard, or crunchy foods should be avoided or specially prepared.

Levels 3 & 4: Pureed and Liquidised

These levels describe foods that are completely smooth and lump-free. Particle size is not a factor because the food is processed to be homogenous. The primary concern is the food's consistency and flow, ensuring it doesn't separate into liquids and solids.

Tools for Measuring IDDSI Particle Size

Accurate measurement is vital for patient safety. IDDSI provides simple, practical testing methods that can be done in any kitchen or care setting.

The Fork Test: For Levels 5 and 6, a standard dinner fork is a key tool. For Level 5, the space between the tines can be used to measure the 4mm lump size. For Level 6, the length of the tines (approx. 1.5cm) is used to check the maximum size of bite-sized pieces.
The Fork Pressure Test: For Level 6, the side of a fork can be used to apply pressure. The food should squash easily and not return to its original shape. For Level 5, the food should mash with minimal pressure.
Fork Drip Test & Spoon Tilt Test: These tests are used for levels like Minced and Moist (Level 5) to ensure food holds its shape but is not too sticky.

How IDDSI Supports Nutritional Intake

Despite the texture modifications, ensuring adequate nutritional intake for dysphagia patients is paramount. Here is how IDDSI helps:

Improved Safety: By reducing the risk of aspiration and choking, IDDSI allows individuals to consume food more safely, encouraging consistent intake rather than avoidance due to fear.
Increased Variety: Standardized levels enable a broader range of foods to be modified safely, allowing for more variety in the diet and better nutrient provision. For instance, recipes for minced meats or tender vegetables can be adjusted for safe consumption.
Addressing Malnutrition: Dysphagia is a significant risk factor for malnutrition. By providing a structured and reliable dietary framework, IDDSI helps healthcare professionals and caregivers manage and prevent malnutrition.

IDDSI Particle Size Requirements Compared


IDDSI Level	Description	Adult Particle Size	Child Particle Size (under 5 years)
Level 7 (Regular)	Normal, everyday foods. May be modified to 'Easy to Chew'	Not restricted (foods must be easy to chew)	Not restricted (foods must be easy to chew)
Level 6 (Soft & Bite-Sized)	Soft, tender, moist foods requiring some chewing	$\le$ 1.5cm x 1.5cm	$\le$ 0.8cm x 0.8cm
Level 5 (Minced & Moist)	Small, soft, moist lumps, mashed by tongue	$\le$ 4mm x 15mm	$\le$ 2mm x 8mm
Level 4 (Pureed)	Smooth, lump-free, holds its shape	N/A (lump-free)	N/A (lump-free)
Level 3 (Liquidised)	Smooth, no lumps, runs off a spoon	N/A (lump-free)	N/A (lump-free)

Conclusion: Prioritizing Safety Through Standardized Sizing

Ultimately, what is the portion size for IDDSI is best understood as a question of particle safety rather than serving quantity. While total nutritional intake remains a primary consideration, the IDDSI framework's core function is to standardize food preparation to minimize the risks associated with dysphagia. By defining precise particle sizes for different food textures, IDDSI provides a clear, universally understood system that protects patients from choking and aspiration. Healthcare providers, caregivers, and food service professionals rely on these standards and simple testing methods to ensure every meal is not only nutritious but, most importantly, safe. For comprehensive resources, refer to the IDDSI framework.

Frequently Asked Questions

No, the IDDSI framework does not specify the total amount of food for meals. It focuses exclusively on food and liquid texture, including particle size for solid foods, to ensure safety. Total food amounts should be determined by a healthcare professional, such as a dietitian, based on individual nutritional needs.

For adults on an IDDSI Level 6 (Soft & Bite-Sized) diet, food pieces should be no larger than 1.5cm x 1.5cm. This is roughly the size of an adult's thumbnail.

To check particle size for IDDSI Level 5 (Minced & Moist), you can use a standard fork. The space between the fork prongs is approximately 4mm, which is the maximum width for lumps. The length of the tines (about 15mm) is the maximum length for minced pieces.

No, particle size restrictions are different for adults and children. For instance, on an IDDSI Level 6 diet, children under 5 have a maximum piece size of 0.8cm x 0.8cm, half the adult size.

For pureed foods (IDDSI Level 4), particle size is not a factor because the food is completely smooth and lump-free. The focus is on the correct consistency, which should hold its shape on a spoon and not drip.

Particle size is crucial for safety on IDDSI diets because it directly impacts the risk of choking and aspiration, especially for individuals with compromised chewing and swallowing abilities. Smaller, softer particles are easier and safer to manage.

Yes, food temperature can affect its texture and consistency. It is recommended to test food under the intended serving conditions, as temperature changes can alter how food behaves and whether it still meets the required IDDSI level.

IDDSI Level 7 (Regular) has no restrictions on particle size. The 'Easy to Chew' descriptor for this level simply means the food should be easily chewed and swallowed, but tough or hard items should be avoided.