Affect vs Effect

Affect vs Effect side by side

Last verified October 2, 2026.

When each one wins

Choose affect when you could swap in influence or change. The new rule will affect most drivers, or caffeine can affect sleep.

Choose effect when you mean the result, especially after the, an or any. The rule had an effect on traffic, or the side effects wore off.

Two rarer uses trip people up. Effect can be a verb meaning to bring about, as in effect change, and affect can be a noun for a visible emotion in psychology.

How this works

Each answer adds points to affect or effect. The two rarer uses carry extra weight because they override the usual verb or noun rule. The quiz totals the points and opens the matching result page.

The rule it teaches is simple: affect is usually a verb, effect is usually a noun.

Where these numbers come from

The figures and defaults on this page are based on:

• Merriam-Webster: affect, Affect as verb (influence), noun in psychology (observable emotion), plus usage note (checked October 2026)
• Merriam-Webster: effect, Effect as noun (result) and verb 'to cause or bring about'; usage note vs affect (checked October 2026)
• Britannica Dictionary: effect, Effect noun 'a change that results'; verb 'to cause/bring about a change' (checked October 2026)

These are general guides. Check specifications and local rules for your situation.