A2 · Elementary

Since, For & Ago: Time Math

Since names the starting point, for measures the stretch, ago counts backwards from now. Three little words, three different kinds of time math.

Since, For & Ago

Three clocks, one question: how long?

When you talk about time stretching, you pick one of three words by the kind of math you are doing: since starts the clock at a point, for measures the stretch, ago counts backwards from now.

🏁

Since — starting point

the clock starts here

I have lived here since 2020

📏

For — duration

the stretch between

I have lived here for five years

⬅️

Ago — distance from now

count backwards

I moved here five years ago

🔗

The partner tenses

since/for love the present perfect, ago loves the past simple

She has worked here since March

⚠️ Since + a point · for + a period · ago + the past simple.

The Formula

Point, stretch, or distance

Watch the same job on three clocks: since pins a point and runs forward, for fills the whole stretch, ago measures back from now.

Since — from a point

2020now

I have worked here since 2020

For — the stretch

5 yearsnow

I have worked here for 5 years

Ago — back from now

5 yearsnow

I started working here 5 years ago

⚠️ Same job, three clocks: point, period, distance.

Common Mistakes

Four time-math slips

The classic mistakes swap the three words, or pair them with the wrong tense. Point, period and distance — each one has its own partner.

✗

I live here since 2019.

→

✓

I have lived here since 2019.

💡 Since + present perfect — the action started then and continues.

✗

I am here for two hours.

→

✓

I have been here for two hours.

💡 For + present perfect for actions still running.

✗

I have lived here since two years.

→

✓

I have lived here for two years.

💡 A period takes for; since takes a point (2019, March).

✗

I have started this job two years ago.

→

✓

I started this job two years ago.

💡 Ago = a finished past moment → past simple.

Quick Quiz

Test what you just learned

Three minutes, five questions — check what stuck. No essay questions, we promise.

Question 1 / 5✅ 0 / 5

We have known each other ___ 2015.

💡 Extra info2 sections

The Recap

Point, period, distance — at a glance

One glance at the three groups and the choice is made.

🏁

Since + a point

a moment in time

since Monday · since 2020 · since 6 p.m.

📏

For + a period

a length of time

for a week · for two years · for ages

⬅️

Ago + past simple

count back from now

a week ago · two years ago · long ago

⚠️ Point → since. Period → for. Distance → ago.

Since or For?

One question picks the word

Since and for both run forward from the past. The difference is what you name: the start line or the stretch.

Do you name the starting point or the length?

✓Starting point — sinceI have worked here since June

✗Length — forI have worked here for six months