What by + reflexive means
In this construction, by combined with a reflexive pronoun means alone or without help from others. In the simple sentences covered here, the pronoun agrees with the subject.
These two meanings—alone, with nobody else present, and without help, with nobody assisting with the task—are closely related but not always identical. Sometimes the context supports only one reading, and sometimes it supports both.
Halyna spent the whole evening by herself, reading in her flat.
Halyna spent the whole evening by herself, reading in her flat.
There is no task being assessed here: the point is that nobody else was present. The meaning is alone.
The interns set up the new printer by themselves, without calling IT support.
The interns set up the new printer by themselves, without calling IT support.
The important point is the absence of help, rather than physical solitude: the meaning is without assistance.
Forming the construction
In the simple sentences covered by this rule, the reflexive form agrees with the subject, not the object or someone mentioned later. I → myself, you (one person) → yourself, you (several people) → yourselves, he → himself, she → herself, it → itself, we → ourselves, they → themselves.
For a compound subject such as my sister and I, first identify the pronoun that could replace the whole subject: here, we. Then choose its reflexive form: ourselves.
by + myself / yourself / himself / herself / itself / ourselves / yourselves / themselves
My colleague and I redecorated the meeting room by ourselves last month.
My colleague and I redecorated the meeting room by ourselves last month.
My colleague and I corresponds to we, so the form is ourselves.
The dog somehow opened the gate by itself.
The dog somehow opened the gate by itself.
The dog is referred to as it here, so the reflexive is itself. If an animal is referred to as he or she, use himself or herself accordingly.
Alone or without help: choosing the meaning
When a sentence describes a task, job or skill—repairing, writing, cooking or assembling something—and contrasts doing it with possible help from other people, the likely meaning is without assistance.
When the focus is simply on the presence or absence of other people—living, staying, waiting or travelling—rather than on a particular task, the likely meaning is alone.
In many natural sentences, the context allows both readings at once. This is not an error: the situation simply supports both meanings.
The mechanic replaced the whole engine by himself over the weekend.
The mechanic replaced the whole engine by himself over the weekend.
Replacing an engine is a task, so the main meaning is without help.
After the guests left, Yulia sat by herself on the porch for a while.
After the guests left, Yulia sat by herself on the porch for a while.
There is no task here: the focus is simply on being alone after the guests have left.
By + reflexive versus an emphatic reflexive without by
Without by, these forms can emphasize the person performing an action: that person personally. This is the emphatic use. A reflexive pronoun without by can also be an object referring back to the subject; that is a separate related rule.
By + reflexive explicitly expresses the absence of company or assistance. An emphatic pronoun highlights who performed the action, and in a suitable context it may also suggest independence. Do not infer whether someone had help solely from the absence of by.
The chef himself served the last dish to the guests.
The chef himself served the last dish to the guests.
Without by, the pronoun adds emphasis: the chef personally, rather than a waiter.
The chef prepared the whole menu by himself, without any kitchen staff.
The chef prepared the whole menu by himself, without any kitchen staff.
With by, the meaning is without help, confirmed by the reference to having no kitchen staff.
Alternatives: alone and on my own
Alone and phrases such as on my own, on your own and on his own convey the same meanings as by + reflexive and are often interchangeable. Alone more often emphasizes physical solitude, while on my own emphasizes independence. The boundary is not always clear, however, and all three options sound natural in many sentences.
Danylo prefers travelling alone rather than in a group tour.
Danylo prefers travelling alone rather than in a group tour.
Alone can be replaced with by himself here without changing the meaning.
She raised three children on her own after her husband moved abroad.
She raised three children on her own after her husband moved abroad.
On her own emphasizes that she bore the main responsibility for bringing up the children. It does not necessarily rule out occasional help from relatives or other people.
Negation and contrast
When we know an action was completed, not by myself can deny that it was done independently: there was help or company. However, a negative sentence alone does not guarantee that the action happened at all. A phrase with with or together with identifies a helper or companion.
I didn't paint the whole fence by myself — my neighbour helped with the last part.
I didn't paint the whole fence by myself — my neighbour helped with the last part.
The following clause explicitly confirms that there was help.
They rebuilt the barn together with two local carpenters, not by themselves.
They rebuilt the barn together with two local carpenters, not by themselves.
Together with explicitly contrasts with the meaning of by themselves.
Common errors and the scope of this rule
A reflexive pronoun is required after by specifically when the meaning is alone or without help. In other constructions, by me or by him can be correct—for example, to identify the agent of a passive verb or to describe a position near someone.
Forms such as hisself, ourself for plural we, theirself and meself occur in the speech of some dialects, but they are not the forms used in the standard English constructions taught here.
This lesson does not provide a full paradigm of reflexive pronoun forms, which is a separate topic. It also does not cover reflexive objects in expressions such as hurt myself, where the subject and object refer to the same person. The focus is the phrase by + reflexive and its contrast with emphatic use without by.
Could you carry this bag by yourself, or do you need a hand?
Could you carry this bag by yourself, or do you need a hand?
A question about completing a task without assistance is a typical natural context for by yourself.
Common mistakes
Incorrect:I moved into this flat by me.
Correct:I moved into this flat by myself.
After by with this meaning, use the reflexive pronoun matching the subject I: myself, not the object pronoun me.
Incorrect:She repainted the entire kitchen by himself.
Correct:She repainted the entire kitchen by herself.
The reflexive pronoun must agree with the subject she, rather than being an arbitrary form.
Incorrect:We fixed the roof by ourself after the storm.
Correct:We fixed the roof by ourselves after the storm.
For ordinary plural we, the standard form is ourselves. Ourself does not fit here.
Incorrect:They moved the sofa by theirself.
Correct:They moved the sofa by themselves.
For plural they, the standard reflexive form is themselves, not theirself.
Incorrect:He can carry it by hisself.
Correct:He can carry it by himself.
Hisself is a nonstandard form; standard English uses himself with he.