factor in

include something when making a plan or calculation

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What does "factor sth in" mean?

To factor in something means to deliberately include it as part of a calculation, budget, or plan, treating it as a variable that will affect the outcome. The phrase carries a sense of numerical or strategic thinking — you are not just vaguely aware of something, but actively building it into your figures or decisions. It is especially common in business, finance, and project planning, where costs, risks, delays, and other measurable elements need to be accounted for before a decision is made. A project manager might factor in overtime costs before finalising a budget, or a traveller might factor in currency exchange rates when calculating holiday expenses. The passive form — 'has been factored in' — frequently appears in professional settings as a way of reassuring others that a particular variable has already been included.

Examples

How to use it

factor in + noun phrase

The most common pattern, used with longer noun phrases that stay after the particle.

The project team forgot to factor in shipping delays when setting the deadline.

factor + noun + in

Used when separating the verb and particle around a shorter noun object, which is natural and very common.

Before you sign the lease, make sure you factor the maintenance costs in.

factor + pronoun + in

Pronouns must always appear between the verb and particle — placing them after 'in' is ungrammatical.

We haven't discussed the overtime budget yet — you need to factor it in.

be factored in

The passive form is natural and common, particularly in formal or professional contexts where the agent is less important than confirming something has been included.

Potential currency fluctuations have already been factored in to the final price.

factor + noun + into + noun

A common variant using 'into' followed by the name of the plan or calculation — it means the same thing.

You should factor the risk of delays into your timeline before presenting it to the client.

Common Collocations

factor in the costfactor in the timefactor in the riskfactor in delaysfactor in inflationfactor in expenses

Common Mistakes

Pronoun after the particle

When the object is a pronoun, it must go between 'factor' and 'in', never after 'in'. Placing a pronoun after the particle is ungrammatical in English.

✗ Did you factor in it when you made the estimate?
✓ Did you factor it in when you made the estimate?
Confusing 'factor in' with 'account for'

'Factor in' is specifically about including a variable in a plan or calculation. 'Account for' can also mean to explain or justify something after the fact — if the meaning is closer to 'explain', 'factor in' does not fit.

✗ The manager was asked to factor in why the project ran over budget.
✓ The manager was asked to account for why the project ran over budget.
Confusing 'factor in' with 'factor out'

'Factor in' means to include something; 'factor out' means to remove or exclude it. These are near-opposites, so using the wrong particle completely reverses the meaning.

✗ Remember to factor out the insurance costs — they're an essential part of the budget.
✓ Remember to factor in the insurance costs — they're an essential part of the budget.

Usage

This phrasal verb is mostly used in professional, business, or planning contexts — it's less common in casual conversation. You may also see the variant 'factor into' followed by a noun ('factor the cost into your budget'), which means the same thing.

Frequently Asked Questions

Is 'factor in' mostly used in formal or professional situations?

It leans toward professional, business, and planning contexts — you'll encounter it frequently in reports, meetings, and financial discussions. In casual conversation, people are more likely to say 'take into account' or simply 'include'. That said, 'factor in' does appear in everyday speech when the situation has a clear planning or calculation element, such as budgeting a holiday or organising an event.

What kinds of things can you 'factor in'?

Typical objects are costs, risks, delays, taxes, inflation, fees, and other measurable variables — things that affect a calculation or outcome. More broadly, you can also factor in less tangible elements like human error, uncertainty, or seasonal variation, as long as there is still a sense of treating them as a deliberate variable in your planning.

What is the difference between 'factor in' and 'factor into'?

'Factor into' is a variant prepositional form where you name the plan or calculation explicitly: 'factor the cost into your budget'. Both forms are correct and mean the same thing — 'factor into' simply makes the target of the calculation explicit. You can choose whichever sounds more natural in context.

Can 'factor in' be used in the present continuous?

It is grammatically possible but sounds unnatural in most situations. 'I am factoring in the delivery costs right now' is rare because 'factor in' typically describes a deliberate decision rather than an ongoing action. The simple present, present perfect, or modal constructions ('you need to factor in') are far more common.

Does 'has been factored in' mean something different from 'has been factored into'?

Not in meaning — both passive forms confirm that something has been included in a calculation or plan. 'Has been factored in' is slightly more self-contained, while 'has been factored into the budget / the estimate' makes the destination explicit. In professional settings, both are equally natural and reassuring.

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