"Used to do" describes PAST habits or states that no longer exist; "be used to doing" describes something you are ACCUSTOMED to (in present, past, or future).
USED TO + infinitive: habitual action or state in the PAST that NO LONGER occurs today. "I used to smoke" = I smoked regularly before (I no longer smoke). "She used to live in Paris" = she lived there habitually (she no longer does). Key points: (1) Only exists in PAST — no present or future form of this structure. (2) Automatically implies the situation has CHANGED. (3) Negative: "didn't use to" or "used not to" (more formal). (4) Question: "Did you use to...?" (not "Used you to...?").
She used to commute two hours every day before the company switched to a hybrid work model.
I used to be terrible at public speaking — it took years of practice to get to where I am now.
Did you use to play an instrument when you were younger? You mentioned something about music classes once.
BE USED TO + gerund (-ing): to be ACCUSTOMED to something, to have done it so often that it no longer feels new or difficult. "I am used to waking up early" = I am accustomed to it (it feels normal to me). "She was used to working long hours" = she was accustomed to it. Unlike "used to do", THIS STRUCTURE CAN BE IN ANY TENSE: "I am / was / will be / have been used to doing it." The verb after "used to" (in this case) is ALWAYS GERUND (-ing), not infinitive.
After six months in the new role, she is finally used to managing a team of twenty people.
Moving to a new country is always challenging at first — you will get used to the cultural differences over time.
He was not used to receiving critical feedback on his work, so the first performance review was quite difficult for him.
Common mistake
Most frequent and serious error: confusing the two structures because of their visual similarity. "I am used to wake up early" = INCORRECT. With "be used to", the following verb is GERUND: "I am used to WAKING UP early." "I used to working late" = INCORRECT. With past habit "used to", the following verb is INFINITIVE: "I used to WORK late." Decision key: PAST HABIT that no longer exists = USED TO + INFINITIVE. BEING ACCUSTOMED to something (any tense) = BE + USED TO + GERUND. The BE is the signal: if there is a form of "to be" before "used to" = BE USED TO + DOING.
Trick to remember it
The SIGNAL TRICK: look for a form of "to be" (am, is, are, was, were, will be, been) BEFORE "used to". IF THERE IS "to be" + "used to" = accustomedness = next verb is -ING. "I AM used to working" / "She WAS used to driving." IF THERE IS NO "to be" and only "used to" = past habit = next verb is infinitive. "I used to work" / "She used to drive." Meaning difference: "I used to drive a truck" = I drove one in the past (I no longer do). "I am used to driving a truck" = I am accustomed to driving one (I find it easy/normal).
Quick rule
Used to + INFINITIVE = PAST habit or state that no longer exists. Be used to + GERUND (-ing) = to be ACCUSTOMED (present/past/future). The verb "to be" before "used to" completely changes the meaning and grammar.
Did you know?
There is a THIRD structure frequently confused with the two above: GET USED TO + GERUND = the PROCESS of becoming accustomed. "I am getting used to the new software" = I am in the process of adapting. "I got used to the commute after a month" = I became accustomed to it (completed process). The three structures form a logical progression: "I used to work from home" (in the past, no longer) -> "I'm getting used to working in the office" (adaptation process in progress) -> "I'm used to working in the office" (fully adapted).
Exercise 1 · Pick the right one
She _____ stay at the office until 9 p.m. every night, but since the restructuring, she leaves by 6.
Exercise 2 · Pick the right one
After two years in the role, he is finally used to _____ presentations to senior leadership every quarter.
Exercise 3 · Form the word
Used to + INFINITIVE = PAST habit or state that no longer exists. Be used to + GERUND (-ing) = to be ACCUSTOMED (present/past/future). The verb "to be" before "used to" completely changes the meaning and grammar.
Most frequent and serious error: confusing the two structures because of their visual similarity. "I am used to wake up early" = INCORRECT. With "be used to", the following verb is GERUND: "I am used to WAKING UP early." "I used to working late" = INCORRECT. With past habit "used to", the following verb is INFINITIVE: "I used to WORK late." Decision key: PAST HABIT that no longer exists = USED TO + INFINITIVE. BEING ACCUSTOMED to something (any tense) = BE + USED TO + GERUND. The BE is the signal: if there is a form of "to be" before "used to" = BE USED TO + DOING.
The SIGNAL TRICK: look for a form of "to be" (am, is, are, was, were, will be, been) BEFORE "used to". IF THERE IS "to be" + "used to" = accustomedness = next verb is -ING. "I AM used to working" / "She WAS used to driving." IF THERE IS NO "to be" and only "used to" = past habit = next verb is infinitive. "I used to work" / "She used to drive." Meaning difference: "I used to drive a truck" = I drove one in the past (I no longer do). "I am used to driving a truck" = I am accustomed to driving one (I find it easy/normal).
Bryan López
Founder of SpeakUP Academy