Other Ways to Say "This Is Because" (Formal and Casual)

On this page13 sections

The one rule to get right: clause or noun?
Quick picker
Neutral replacements for essays and reports
Academic and cautious options
Turning it around: putting the cause first
Joining the sentences instead
In conversation and emails
When there is more than one cause
Because, since, as and for: small differences
Before and after: rewriting real sentences
Common mistakes
Practice
Quick answers

Good other ways to say “this is because” are this is due to, the reason is that, this happens because, this stems from, this can be explained by, that’s why (reversing the order) and simply because joined to the previous sentence. In academic writing, this is largely due to, this reflects and this can be attributed to sound natural; in conversation, that’s because and the thing is are more common. The right choice depends on one grammar point that trips up many writers: some phrases must be followed by a full clause, others by a noun.

The one rule to get right: clause or noun?

“This is because” is followed by a clause (a subject and a verb): This is because the soil is too dry. Several of its replacements are followed by a noun phrase instead. Mixing them up is the most common error with this group.

Followed by a clause (subject + verb)	Followed by a noun phrase
This is because prices rose.	This is due to the rise in prices.
The reason is that the bus was late.	This results from a delay in the bus service.
This happens because the cells lose water.	This is caused by water loss in the cells.
That’s because nobody told her.	This stems from poor communication.
One reason is that funding was cut.	This can be attributed to a lack of funding.

If you want to use a noun phrase but your idea is a clause, turn it into a noun: “the bus was late” becomes “the late bus” or “the delay”. If you want to keep the clause, add the fact that: “This is due to the fact that the bus was late” – correct, but wordy, so use it sparingly.

Quick picker

Situation	Try
Essay or report, neutral	This is due to / This is largely because / The main reason is that
Academic, cautious	This may be explained by / This is likely to reflect / One possible explanation is that
Academic, tracing an origin	This stems from / This arises from / This can be traced to
Assigning responsibility	This can be attributed to / This is the result of
Work email	This is because / The reason for this is / This is down to (UK)
Conversation	That’s because / It’s because / The thing is
Putting the cause first	As a result, / That’s why / This explains why

Neutral replacements for essays and reports

This is due to + noun. “Sales fell in March. This is due to the closure of two stores.” Some older style guides insist “due to” should only follow a form of be (as it does here); used that way, nobody will object.
The reason (for this) is that + clause. “The reason for this is that most customers now shop online.” Avoid “The reason is because” in formal writing; it repeats the idea of reason, and many teachers mark it wrong.
This is largely / partly / mainly because + clause. Adding an adverb is often the best improvement, because few effects have a single cause. “This is partly because the survey was run in August, when many students were away.”
This happens because + clause. Good for explaining processes. “Ice floats. This happens because water expands as it freezes.”
This occurs because – the same, slightly more formal; common in science writing. “Rust forms on the bolt. This occurs because iron reacts with oxygen and moisture.”
The main reason is + noun, or the main reason is that + clause. “The main reason is cost.” / “The main reason is that it costs less.”

Academic and cautious options

In academic writing you often cannot be certain about causes. These phrases let you explain without overclaiming.

This can be explained by + noun. “The higher scores in Group B can be explained by the extra practice time.”
This may be explained by the fact that + clause. “This may be explained by the fact that the sample was small.”
One possible explanation is that + clause. “One possible explanation is that participants guessed the purpose of the study.”
This is likely to reflect + noun. “The drop in responses is likely to reflect survey fatigue.”
This suggests that – careful: this introduces a conclusion, not a cause. “Response rates fell after the third email. This suggests that participants were tired of reminders.”
This stems from + noun. Use it when the effect has grown out of an earlier source. “Much of the confusion stems from the vague wording of the law.”
This arises from + noun. “The problem arises from a mismatch between supply and demand.”
This can be traced (back) to + noun. Good for history and origins. “The tradition can be traced back to the 1800s.”
This can be attributed to + noun. “The improvement can be attributed to the new training programme.” It sounds formal and suits reports and theses.
This reflects + noun. “The low turnout reflects widespread distrust of the process.”

Turning it around: putting the cause first

“This is because” explains an effect you have just mentioned. Sometimes the paragraph reads better if you give the cause first and then the result.

That’s why / This is why + clause. “The roads were icy. That’s why the school closed.” “This is why” is fine in essays; “that’s why” is more conversational.
As a result, / Consequently, / Therefore,. “The roads were icy. As a result, the school closed.” See other words for “as a result” for more.
This explains why + clause. “Most of the town’s young people work in the city. This explains why the population falls on weekdays.”
This leads to + noun. “Skipping breakfast often leads to poor concentration.”

Joining the sentences instead

Often “This is because” is not needed at all. Two short sentences can become one, which is clearer:

“The meeting was cancelled. This is because the manager was ill.” → “The meeting was cancelled because the manager was ill.”
“Many plants die in winter. This is because of the frost.” → “Many plants die in winter because of the frost.”
“I prefer trains. This is because I can read on them.” → “I prefer trains, as I can read on them.” or “I prefer trains since I can read on them.”

Keep the separate sentence when the explanation is long or deserves emphasis – for example, the main finding of a paragraph. For the single word “because”, see our page of other ways to say “because”.

In conversation and emails

That’s because – the natural spoken form. “You’re tired? That’s because you stayed up until two.”
It’s because – when the subject is “it”. “It’s because the printer is out of paper.”
The thing is – introduces a reason, often a reason for refusing or delaying something. “I’d love to come. The thing is, I’ve already promised to help my brother move.”
It’s down to (UK, informal) + noun. “The delay is down to a staff shortage.” In British English “down to” can also mean “it’s someone’s responsibility” (“It’s down to you now”), so check the sense.
Thanks to + noun – used for good results, or ironically for bad ones. “We finished early, thanks to Ana’s planning.” / “Thanks to the traffic, we missed the start.”
The reason for this is – polite and clear in work emails. “Your order will arrive on Friday. The reason for this is a delay at our warehouse.”

When there is more than one cause

Real explanations often have several causes, and “This is because” can make one of them sound like the whole story. These patterns help you list and rank causes:

There are two main reasons for this. First, … Second, … Clear and easy to follow in an essay. “There are two main reasons for this. First, rents have doubled. Second, wages have barely moved.”
This is partly because … and partly because … “This is partly because the trains are unreliable and partly because parking is free.”
Several factors contribute to this, including … + nouns. “Several factors contribute to this, including diet, sleep and stress.”
A key factor is … / Another factor is … Useful when you discuss each cause in its own paragraph.
This is not only because … but also because … Adds emphasis to the second cause. “This is not only because the tickets are expensive but also because the venue is hard to reach.”

Because, since, as and for: small differences

These four words can all introduce a reason, but they are not fully interchangeable.

Because puts weight on the reason and is the only one that answers a “why” question directly: “Why are you late?” “Because the bus broke down.”
Since and as usually give a reason the listener already knows or will accept easily, and they often come first: “Since you’re here, can you help me lift this?” “Since” can also mean “from a time”, so avoid it where the time sense could confuse: “Since he moved, he has been happier” is ambiguous.
For as a reason word is literary and rather old-fashioned, and it never starts the sentence in this sense: “She said nothing, for she was afraid.”

Before and after: rewriting real sentences

Original	Better
Bees are in decline. This is because of pesticides, habitat loss and disease.	Bees are in decline. This is largely due to pesticides, habitat loss and disease.
The novel was banned. This is because it criticised the government.	The novel was banned because it criticised the government.
The data are uneven. This is because the regions reported at different times.	The data are uneven. One reason is that the regions reported at different times.
Our costs are up. This is because suppliers raised prices.	Our costs are up, mainly because suppliers raised prices.
The bread didn’t rise. This is because the yeast was old.	The bread didn’t rise. The old yeast was to blame.
Prices fell. This is because demand dropped.	Demand dropped. As a result, prices fell.

Common mistakes

“This is due to the price rose.” “Due to” needs a noun. Write “This is due to the rise in price” or “This is because the price rose.”
“The reason is because…” Redundant in formal writing. Write “The reason is that…” or just “This is because…”
“This is since…” Not idiomatic. “Since” can mean “because” at the start of or within a sentence (“Since it was raining, we stayed in”), but not after “This is”.
“This is caused because…” Mixes two patterns. Write “This is caused by…” + noun or “This happens because…” + clause.
“Because of this reason” Wordy. Write “for this reason” or “because of this”.
Using “this” without a clear reference. If the previous sentence contains several ideas, “This is because” can be vague. Add a noun: “This decline is because…” or better, “This decline is largely due to…”
Stating a cause too strongly. In research writing, “This is because” claims certainty. If you only have a correlation, use “This may be because” or “One explanation is that”.

Practice

Rewrite each sentence using the phrase in brackets.

The river flooded. This is because it rained for a week. (due to)
Students did better in the second test. This is because they had more time. (can be explained by)
The software keeps crashing. This is because there is a bug in the update. (caused by)
The company lost customers. This is because its service was poor. (stems from)
He missed the train. This is because he overslept. (join with because)
The festival is held in June. This is because of an old harvest custom. (can be traced back to)

Answers:

The river flooded. This was due to a week of rain.
Students did better in the second test. This can be explained by the extra time they had.
The software keeps crashing. This is caused by a bug in the update.
The company lost customers. This stems from its poor service.
He missed the train because he overslept.
The festival is held in June. The date can be traced back to an old harvest custom.

Note answer 1: when the effect is in the past, the tense usually changes too (This was due to). “This is because” is often used for past events in explanations, but matching the tense is safer in formal writing.

Quick answers

Can I start a sentence with “This is because”?

Yes. It is grammatical and common in essays. The problem is only overuse; if three paragraphs in a row use it, swap in some of the options above or join sentences.

Is “This is due to” more formal than “This is because”?

Slightly. Both are fine in academic writing. “Due to” must be followed by a noun phrase.

What is a formal way to say “this is because”?

This can be attributed to, This arises from, This is largely due to and The principal reason is that all sound formal. For neutral linking words more generally, see other words for “explain”.