Unless and if not: state an exception clearly

The idea

Use unless + clause. For an ordinary future condition, use a present form: unless they arrive. Put a comma after an initial unless-clause. A negative main clause is possible: won't ... unless.

Examples

• We'll keep the old shelves unless the new ones arrive today.
• Unless the label says otherwise, wash this scarf by hand.
• The kettle won't switch on unless the lid is closed.
• I'll take the spare chair unless you need it.
• If the new shelves don't arrive today, we'll keep the old ones.
• The gate usually stays open unless there is a delivery.

Watch out

Do not write unless if or automatically keep not when replacing if not. A negative after unless can be meaningful, but changes the condition. The words are not interchangeable in every context, especially imagined alternatives to known past facts.

Try it yourself

1. Choose the correct option. We'll keep the old shelves unless the new ones ___ today. (arrive / will arrive)

   Show answer or example answer

   arrive

   Arrive is present simple; it expresses the ordinary future condition after unless.

2. Choose the correct option. The kettle won't switch on unless the lid ___ closed. (is / are)

   Show answer or example answer

   is

   Singular the lid takes is. Closing the lid is a necessary condition, not a guarantee that a broken kettle will work.

3. Choose the correct option. Unless the label says otherwise = if the label does ___ say otherwise. (not / always)

   Show answer or example answer

   not

   Not makes the equivalent condition: follow this instruction if the label does not give another one.

Use it today

Write a plan for using old equipment and its one exception. Rewrite your sentence with if ... not, then check that both versions describe the same situation.