IB essay criteria explained

Most IB coursework is marked against published criteria with fixed mark allocations. The TOK essay and exhibition are the exception: they are marked holistically, as a single global impression. The fastest way to raise a grade is to find the heaviest criterion for your component and check your draft against its top markband first.

One of the most distinctive features of the IB Diploma Programme is its use of criterion-based assessment. Unlike norm-referenced systems (where your grade depends on how you perform relative to other students), the IB assesses each piece of work against fixed criteria with defined descriptors. This means that in theory, every student in a cohort could achieve a 7, or every student could receive a 3, depending on how well their work meets the criteria.

Knowing how criterion-based marking works shows you where to aim your revision. When you know exactly what examiners are looking for at each level, you can write strategically to demonstrate those qualities. This guide explains the system, shows you what distinguishes different performance levels, and gives you tools for self-assessment.

Why criterion-based marking exists

The IBO uses criterion-based assessment for several reasons:

Consistency across contexts: IB students study in many countries with different educational traditions. Criterion-based marking ensures that a 7 in History means the same thing whether the student is in Singapore, Germany, or Brazil. Examiners worldwide apply the same criteria to the same standard.

Transparency: Students can read the criteria before they begin their work and understand exactly what is expected. The criteria are published in the subject guides, and your teacher can share them with you.

Developmental feedback: Because criteria describe specific competencies at different levels, teachers can give targeted feedback: "Your analysis is at band 3-4; to reach band 5-6, you need to evaluate the reliability of your sources rather than just citing them."

Fairness: Criterion-based marking reduces (though does not eliminate) the impact of examiner subjectivity. When examiners disagree, they can point to specific descriptors and discuss which level the work best matches.

Common criteria across subjects

While each IB subject has its own specific criteria, certain competencies appear across nearly all subjects. Understanding these common threads helps you develop transferable skills:

Knowledge and understanding

Every IB subject assesses whether you understand the relevant content, concepts and terminology. At lower levels this means accurate recall and basic application. At higher levels it means deep understanding: seeing connections between concepts, understanding why something works and not just that it does, and using terminology precisely.

Application and Analysis

This criterion assesses whether you can apply your knowledge to specific situations and break down complex problems into components. In sciences, this might mean applying a theory to explain experimental results. In humanities, it might mean analysing a primary source by considering its context, purpose, and limitations. The key distinction: description tells what; analysis tells why and how.

Synthesis and evaluation

The highest-order thinking skill assessed in the IB. Synthesis means combining ideas from different sources or perspectives to create new understanding. Evaluation means making reasoned judgements about the value, reliability, or significance of evidence, arguments, or methods. In many criteria, evaluation is what separates the upper levels from the middle ones.

Communication and presentation

Assessed directly in many components, and indirectly in all of them: can you communicate your ideas clearly, using appropriate structure, conventions and academic language? This includes proper citation, logical organisation, correct use of subject-specific formats (lab reports, essays, commentaries), and writing that is precise rather than vague.

How examiners apply criteria in practice

Understanding the mechanics of marking helps you write for your audience. Here is how the process typically works:

Best-fit approach: Examiners do not mark individual sentences or paragraphs. Instead, they read the entire piece of work and then determine which band descriptor best fits the overall quality for each criterion. This means that a few weak paragraphs will not necessarily drag down your mark if the overall quality is strong, but it also means that one brilliant paragraph cannot compensate for generally weak work.

Positive marking: IB examiners are trained to look for evidence of achievement rather than counting errors. They ask "What has this student demonstrated?" rather than "What mistakes did they make?" This is why it is important to show your thinking: even if your conclusion is slightly off, strong analytical reasoning earns marks.

Holistic reading: Examiners read the entire response before assigning marks. They do not allocate marks paragraph by paragraph. This means your essay needs to work as a coherent whole: an introduction that sets up the argument, a body that develops it logically, and a conclusion that draws the findings together.

Standardisation: examiners are trained on work that senior examiners have already marked, and their marking is checked during the session. The aim is that different examiners marking the same work arrive at similar marks.

The difference between good and excellent work

Many students reach solid, good work without much trouble and then struggle to break into the top levels. The exact wording differs from criterion to criterion, but these differences come up again and again:

The fundamental difference is depth of thinking. Good work shows competence: the student understands the material and can apply it. Excellent work shows intellectual sophistication: the student can evaluate, synthesise and reach insight of their own.

Self-assessment using criteria

One of the most effective study strategies is to assess your own work against the published criteria before submitting it. Here is a practical approach:

Step 1: Obtain the criteria. Every IB subject guide contains the assessment criteria for each component. Your teacher should have shared these with you. If not, ask: you should know exactly how your work will be assessed.

Step 2: Read the top band descriptors. For each criterion, read the descriptor for the highest band (typically band 5-6 or band 7-8 depending on the scale). This tells you what "excellent" looks like for that criterion.

Step 3: Highlight evidence in your work. Go through your essay or IA and highlight where you have demonstrated each criterion. If you cannot find clear evidence of a criterion, that is a gap you need to fill.

Step 4: Compare to band descriptors. For each criterion, honestly assess which band your work currently sits in. The gap between your current band and the top band tells you exactly what you need to improve.

Step 5: Targeted revision. Focus your revision effort on the criteria where you have the largest gap between current performance and target. There is no point polishing presentation if the criterion carrying the most marks in your own rubric is still at the bottom band.

How AI feedback maps to criteria

Tools like IBLens follow the same criterion-based approach. When you paste an essay, a language model reads your work against the criteria for your subject, essay type and session, and returns:

• Per-criterion scores: An estimated mark for each criterion that can be judged from your text, showing where you are strong and where you need improvement
• Band-level feedback: Explanation of which band your work currently matches
• Specific evidence: Pointing to particular sections of your essay that demonstrate (or fail to demonstrate) each criterion
• Actionable suggestions: Concrete steps you can take to improve your score on each criterion

This is useful because self-assessment has a built-in limit: it is hard to judge your own work objectively, especially after weeks inside it. An external perspective (whether from a teacher, peer, or AI tool) can identify blind spots that you cannot see yourself.

The key advantage of criterion-based AI feedback over general writing feedback is specificity. Generic feedback like "your essay needs more analysis" is unhelpful because it does not tell you which criterion is weak, where in the essay the analysis is lacking, or what analysis at the next band level looks like. Criterion-mapped feedback addresses all three.

Practical tips for criterion-based writing

A few habits that help:

• Address every criterion explicitly. If a criterion asks for "evaluation of sources," make sure there is a visible section or paragraph where you evaluate sources. Do not assume the examiner will infer it.
• Make the criterion's work visible, not its vocabulary. Phrases like "a critical examination reveals" earn nothing on their own; the evaluation itself does. Check that each criterion has somewhere in the work where it is clearly being done.
• Make your question and approach clear early. Best-fit marking reads the whole piece, and a reader who knows from the first page what you are trying to show can see how each section serves it.
• Do not sacrifice one criterion for another. A beautifully written essay (high communication marks) that lacks analysis will not score well overall. Balance your effort across all criteria.
• Check word and page limits. In many components, including the Extended Essay, the TOK essay and exhibition, and the Economics and Business Management IAs, examiners or moderators stop reading at the limit; everywhere else it is still a rule, except in the Mathematics exploration, which has only a suggested length of about 12 to 20 pages.

For subject-specific guidance on how criteria apply to different essay types, see our guides on the Extended Essay, Internal Assessment, and TOK Essay. To understand how criterion scores translate into final grades, read our IB grade boundaries explainer.