Lay vs Lie: which is correct?

The object test for the present tense

In the present tense, the difference between lay and lie comes down to one question: is something being placed? Lay is transitive, meaning it requires a direct object, the thing you are putting down. You lay something: lay the book on the table, lay your cards on the table, lay the baby in the crib, hens lay eggs. There is always an answer to the question lay what?

Lie is intransitive, meaning it takes no object. The subject does the lying on its own. You lie down, the dog lies by the fire, the village lies in a valley, your keys lie on the counter. There is no lie what?, because nothing is being placed; the subject is simply reclining or being situated. So the present-tense test is quick: if you can name the thing being put down, use lay; if the subject is reclining by itself, use lie.

Why the past tenses cause chaos

Here is the cruel twist that makes this pair genuinely hard. The past tense of lie (to recline) is lay. The same spelling as the present tense of the other verb. So yesterday I lay down for an hour is correct for the reclining verb, even though lay also exists as its own present-tense verb. This collision is the single biggest source of error, because lay down can be either the present of to place (lay it down now) or the past of to recline (I lay down yesterday).

The full picture: lie (recline) goes lie, lay, lain (I lie down today, I lay down yesterday, I have lain down before). Lay (place) goes lay, laid, laid (I lay it down today, I laid it down yesterday, I have laid it down before). Notice that laid, with an i, is the past of the placing verb, while lay, the bare form, is the past of the reclining verb. If you remember nothing else, remember that laid always belongs to the placing verb and always needs an object: you laid something.

Worked examples across tenses

Lay (to place), present: I lay the keys on the hook every evening. Past: yesterday I laid the keys on the hook. Perfect: I have laid the keys there for years. Every one has an object, the keys, and the past forms use laid with an i.

Lie (to recline), present: I lie down after lunch. Past: yesterday I lay down after lunch. Perfect: I have lain down every afternoon this week. None has an object, and the past is the bare lay while the perfect is lain. The sentence I have lain in bed all morning is correct and is the form people most often get wrong, usually writing laid instead.

Put the trap in one place: today I lie on the sofa; yesterday I lay on the sofa; but today I lay the blanket on the sofa, and yesterday I laid it there. Reading that sequence slowly, and noticing that the version with a blanket (an object) is the laid/lay-place verb, is the fastest way to internalise the difference.

A reliable proofreading routine

When you hit a lay or lie while editing, ask two questions in order. First: is there an object, a thing being placed? If yes, you are in the lay/laid/laid family (place). If no, you are in the lie/lay/lain family (recline). Second: which tense is it? That pins down the exact form. The object question is the master key, because it tells you which verb you are even dealing with before tense matters.

Watch especially for I laid down, which is one of the most common errors in English. If nothing was placed, you reclined, so the correct past is I lay down, not I laid down. Reserve laid for sentences with an object: I laid the book down. Because both lay and lie are valid words in multiple tenses, spell-check is useless here, so this is a pair where understanding the object test genuinely pays off. Practise on the quiz above and then watch your own drafts for laid down, the tell-tale slip.