ESEN
Which one to use?Beginnerprepositionadverb
SincevsAgo
'Since' marks the starting point of something active until the present; 'ago' indicates distance into the past from now.
Side-by-side comparison
Since
preposition"Since" indicates the starting point of an action that continues up to now. It is used with perfect tenses: "I have lived here since 2010".
She has lived in Barcelona since she graduated from university three years ago.
He has been learning the piano since he was seven, he plays really well now.
I have not seen her since the last time we met at Maria's birthday party last summer.
Ago
adverb"Ago" indicates how long before the present something happened. It is used with the past simple: "I moved here two years ago". It cannot go with perfect tenses.
She moved to this city two years ago and loves it more every single day.
We met a few months ago at a language exchange event in the centre of town.
He finished school five years ago and has been working in the same company ever since.
Common mistake
Two classic errors:
- 1."I moved here since three years" is wrong: "since" marks a POINT IN TIME ("since 2021"), not a duration; use "for" for duration: "I have lived here FOR three years."
- 2."She has arrived two hours ago" is wrong: "ago" always goes with simple past, never with present perfect: "She ARRIVED two hours ago."
Trick to remember it
- •Three mental time pointers: AGO points a finger at a past moment ("happened there, done"). SINCE draws a line from that moment up to TODAY (still ongoing). FOR measures the total length of that line.
- •AGO + simple past (finished). SINCE/FOR + present perfect (still active).
Quick rule
"Since" = starting point until now (+ present perfect). "Ago" = distance to past (+ simple past). "For" = total duration (+ present perfect). "Since 2020" (when it started). "Two years ago" (when). "For two years" (how long).
Did you know?
The word AGO is one of the oldest terms in English still in active use. It comes from Old English "agan" (meaning "to pass," as time passes). In Shakespeare's English, AGO was frequently interchangeable with SINCE in the same temporal meaning: "three hours since" (three hours ago) was as valid as "three hours ago." The regularization of AGO as an exclusive adverb of distance to the past (always with simple past) occurred gradually between the seventeenth and nineteenth centuries and is today one of the most uniform rules in modern English.
Practise what you learned
Exercise 1 · Pick the right one
She left the company two years _____ . Nobody has heard from her since.
Exercise 2 · Pick the right one
I've known him _____ we were at school together.
Exercise 3 · Form the word
Related word pairs
InvsOn / At
'In' goes with broad periods; 'on' goes with specific days and dates; 'at' goes with exact moments.
Simple pastvsPresent perfect
Simple past indicates a completed action at a specific past moment; present perfect connects the past to the present.
SincevsFor
"Since" marks the specific point when something started; "for" indicates how long something has lasted.
AvsAn
'A' is used before consonant sounds; 'an' is used before vowel sounds.
Bryan López
Founder of SpeakUP Academy