Learn Present Real Conditional in English
Express facts and general truths using if + present simple.
Grammar Focus
The present real conditional (also called the zero conditional) expresses facts, general truths, scientific laws, and habitual results. When a particular condition is always true, the result is also always true — there is no uncertainty involved. This structure is different from other conditional forms because it does not describe a hypothetical situation; it describes something that reliably happens every time.
- Use if + present simple in the condition clause (the *if* clause)
- Use present simple in the result clause (the *main* clause)
- The if clause can come first or second in the sentence — when it comes first, use a comma after it
- You can replace if with when to emphasise that the result is inevitable or automatic
- Common signal words: always, usually, generally, every time, whenever
Form & Structure
Affirmative
Negative
Questions
Common Mistakes
Using 'will' in the if-clause
Tip: In the present real conditional, never use **will** in the *if* clause. Both clauses use the present simple because you are describing a fact, not a prediction.
Using future tense in the result clause
Tip: The zero conditional result clause stays in the **present simple** because the outcome is always true, not just a future possibility. Save 'will' for the first conditional.
Forgetting the comma when the if-clause comes first
Tip: When the **if** clause comes at the beginning of the sentence, always place a **comma** between the two clauses. No comma is needed when the result clause comes first.
Why This Grammar Matters
Science and nature — stating physical and biological facts
Instructions and procedures — explaining what reliably happens
Personal habits and routines — describing your own typical behaviour
Advice and general wisdom — sharing universal truths
Continue Learning
Future Real Conditional
Same category (Conditionals) and level
Present/Future Unreal Conditional
More conditionals lessons
Past Unreal Conditional
More conditionals lessons
Mixed Conditionals
More conditionals lessons
Adverbs of Manner
intermediate companion topic
Adverbs of Frequency
intermediate companion topic
This lesson content was created with AI assistance and reviewed for accuracy.
Quick Summary
| Use | Formula | Example |
|---|---|---|
| Affirmative | **If** + present simple, present simple (general truth/fact) | **If** you heat water to 100°C, it **boils**. |
| Negative | **If** + present simple (negative), present simple | **If** you **don't** water plants, they **wither**. |
| Questions | **What happens if** + present simple? | **What do you do if** + present simple? | **What happens if** you mix red and blue paint? |
One of the most fundamental building blocks of English grammar is the ability to talk about cause and effect — to explain what always happens when a particular condition is met. This is exactly what the present real conditional, also known as the zero conditional, allows you to do. Whether you are describing a scientific law, explaining how something works, sharing a personal habit, or giving advice based on universal experience, the present real conditional is the grammatical structure you will reach for. For intermediate English learners, the present real conditional is often taught alongside other conditional forms, and it is important to understand exactly how it differs from them. Unlike the first conditional, which talks about possible future outcomes, or the second conditional, which describes hypothetical or unlikely situations, the zero conditional deals exclusively with facts. When you say "if you heat ice, it melts," you are not speculating — you are stating a truth that applies every single time, without exception. This lesson guide will walk you through everything you need to know about the present real conditional in English. You will learn what it is, when to use it, how to construct it correctly in affirmative sentences, negatives, and questions, and how to avoid the mistakes that English learners most commonly make with this structure. You will also see how native speakers use this conditional form in everyday contexts — from science class to casual conversation. By the end of this guide, you will be able to use the present real conditional confidently and accurately, and you will understand exactly why it behaves differently from the other English conditional forms. Let's get started.
What is the Present Real Conditional?
The present real conditional — most commonly called the zero conditional — is a sentence structure that connects a condition with a result that is always true whenever that condition is met. The word 'zero' in the name refers to the fact that there is zero uncertainty: the result is not a prediction or a wish, it is a guaranteed fact. The structure is built from two clauses. The first is the condition clause, which begins with the word if (or sometimes when). The second is the result clause, which states what always happens when that condition is true. Both clauses use verbs in the present simple tense. Here are some clear examples: 'If you combine hydrogen and oxygen, you get water.' 'If temperatures drop below zero, water freezes.' 'If I stay up too late, I feel tired the next day.' In every case, the condition reliably produces the same result — no exceptions, no guessing. This conditional form is called 'real' because it describes actual reality rather than imagination or possibility. It is also sometimes called the 'factual conditional' for this reason. You will encounter it constantly in scientific writing, instructional texts, recipe books, academic explanations, and everyday speech whenever someone is sharing general truths or predictable outcomes.
Read the full grammar guide
When to Use the Zero Conditional
The zero conditional is the right choice whenever you want to communicate something that is universally or habitually true. Understanding the different contexts where it applies will help you use it naturally and accurately. The most classic use is for scientific facts and natural laws. When you explain how the physical world behaves — how chemicals react, how temperature affects matter, how biological processes work — the zero conditional is the standard grammatical choice. Examples include: 'If you heat iron, it expands.' 'If plants do not get carbon dioxide, they cannot photosynthesise.' These are permanent, repeatable facts. The zero conditional is also widely used for instructions and operational explanations — telling someone what reliably happens when they perform a specific action. 'If you press the power button, the screen turns on.' 'If you add yeast to the dough, it rises.' This use appears frequently in manuals, recipes, and how-to guides. A third important use is for personal habits and routines — things that you or other people reliably do or experience under certain conditions. 'If I drink too much coffee, I can't sleep.' 'If she feels stressed, she goes for a run.' Finally, the zero conditional appears in general wisdom and advice. Proverbs and universally accepted truths often follow this pattern: 'If you don't look after your health, your body suffers.' This usage communicates timeless knowledge that applies to everyone.
How to Form the Present Real Conditional
Forming the present real conditional is straightforward once you understand its two-part structure. The key rule is that both clauses — the condition clause and the result clause — use verbs in the present simple tense. The condition clause always begins with if (or when for results that are especially automatic or inevitable). The result clause states what happens as a consequence. The word order within each clause follows the standard pattern of English declarative sentences: subject + verb + object or complement. For affirmative sentences: 'If you heat water to 100 degrees Celsius, it boils.' 'If I eat too much sugar, I feel sick.' 'The machine stops if you press the red button.' For negative sentences, you use the negative present simple (do not / does not) in either or both clauses: 'If you do not water the plants, they die.' 'If she does not practise, she does not improve.' 'The alarm does not sound if you enter the correct code.' For questions, you can ask what happens under a given condition, or you can turn the whole sentence into a yes/no question: 'What happens if you mix vinegar and baking soda?' 'Does metal rust if it gets wet?' 'What do you do if you lose your keys?' An important punctuation point: when the if-clause comes first in the sentence, you must place a comma between the two clauses. 'If you study hard, you succeed.' When the result clause comes first, no comma is needed: 'You succeed if you study hard.' Both word orders are grammatically correct — the meaning does not change.
Common Mistakes with the Present Real Conditional
Even learners who understand the concept of the zero conditional make predictable errors when constructing these sentences. Knowing the most common mistakes will help you avoid them. The most frequent error is using 'will' inside the if-clause. Because the zero conditional is closely related to the first conditional in appearance, learners sometimes blur the two and write things like 'If you will mix these chemicals, they will react.' The correct zero conditional form is 'If you mix these chemicals, they react.' Remember: will belongs in the first conditional (possible future situations), not the zero conditional (always-true facts). A closely related error is using future tense in the result clause when a general truth is intended. 'If you touch a hot stove, you will burn yourself' is a first conditional sentence — it describes a possible consequence. 'If you touch a hot stove, you burn yourself' is the zero conditional — it states a universal fact. Both are grammatically valid, but they convey subtly different meanings. For pure facts and scientific laws, the zero conditional with present simple in both clauses is the more precise choice. A third common mistake is omitting the comma when the if-clause is placed at the beginning of the sentence. Learners frequently write 'If you leave milk out it goes sour' when the correct form is 'If you leave milk out, it goes sour.' The comma signals the boundary between the two clauses and is an important feature of written English. Finally, some learners confuse the subject-verb agreement in the present simple. Remember that third-person singular subjects (he, she, it, a noun referring to one person or thing) require an -s ending on the verb: 'If the temperature drops, water freezes.' 'If she eats too much salt, she feels bloated.' Forgetting this -s is a very common error in the result clause.
Zero Conditional vs First Conditional
The zero conditional and the first conditional look similar, and many learners struggle to distinguish between them. Understanding the key difference will sharpen your grammar significantly. The zero conditional describes universal truths — things that are always true without any doubt. Both clauses use the present simple: 'If you heat ice, it melts.' This is a fact of physics — it happens every single time, under all circumstances. The first conditional describes possible or likely future situations. The if-clause uses the present simple, but the result clause uses will + infinitive: 'If it rains tomorrow, I will take an umbrella.' This is not a guaranteed outcome — it is a prediction about a specific possible future event. A useful test is to ask: 'Is this always true, or is it about one possible future situation?' If the answer is 'always true,' use the zero conditional. If the answer is 'one possible future event,' use the first conditional. In practice, native speakers sometimes use will in zero conditional contexts for extra emphasis or when talking to someone directly ('If you touch that wire, you will get a shock'), but in academic and formal writing, the pure zero conditional with present simple in both clauses is strongly preferred for stating facts.
Practice In This Page
1. _____ you heat water to 100°C, it **boils**.
Show answer
If
2. _____ you **don't** water plants, they **wither**.
Show answer
If
3. If you will heat water, it boils.
Show answer
If you **heat** water, it boils.
4. If you mix red and blue, you will get purple.
Show answer
If you mix red and blue, you **get** purple.
5. If you touch fire you get burned.
Show answer
If you touch fire**,** you get burned.
Frequently Asked Questions
- What is the zero conditional used for?
- The zero conditional (also called the present real conditional) is used to express facts, scientific laws, and general truths — situations where a condition always produces the same result. Examples include natural laws ('If you heat water to 100°C, it boils'), habitual behaviour ('If I skip breakfast, I feel hungry by 10 a.m.'), and instructions ('If you press this button, the alarm stops').
- Can I use 'when' instead of 'if' in the zero conditional?
- Yes, you can often replace 'if' with 'when' in the zero conditional, especially when the result is completely automatic or inevitable. 'When you heat ice, it melts' sounds just as natural as 'If you heat ice, it melts.' The word 'when' can emphasise that the result happens every single time without exception, whereas 'if' is slightly more neutral.
- What is the difference between the zero conditional and the first conditional?
- The zero conditional uses present simple in both clauses and expresses general truths: 'If you leave food out, it goes bad.' The first conditional uses present simple in the if-clause and will + infinitive in the result clause, and it expresses possible future situations: 'If you leave the food out, it will go bad.' The zero conditional is about facts; the first conditional is about predictions.
- Do I need a comma in zero conditional sentences?
- Yes, when the if-clause comes at the beginning of the sentence, you need a comma to separate the two clauses: 'If you freeze water, it turns to ice.' If the result clause comes first, no comma is needed: 'Water turns to ice if you freeze it.' Both word orders are equally correct, and the comma rule is the same as for all conditional structures in English.
- Can I use 'will' in the zero conditional?
- No. In the zero conditional, you should not use 'will' in the if-clause. The if-clause always uses the present simple: 'If you heat water, it boils' — not 'If you will heat water.' In the result clause, native speakers sometimes use will for emphasis, but in formal and academic writing the present simple is standard for stating facts.
- What are some signal words for the zero conditional?
- Common time expressions and adverbs that appear with zero conditional sentences include: always, usually, generally, normally, often, every time, whenever, and never. These words reinforce the idea of a repeatable, habitual, or universal situation. For example: 'If I drink too much coffee, I always get a headache.' 'Whenever it rains heavily, the road floods.'