hosuu ga mokuhyouhosuu ni todoku.

• 歩数 = ほすう

  • 歩 = step
  • 数 = number/count

• 目標歩数 = もくひょうほすう

  • 目標 = target/goal
  • 歩数 = step count

• 届く = とどく
  This verb often means to reach, to arrive, or to get to.

So the full sentence is read:

ほすう が もくひょうほすう に とどく。

が marks the grammatical subject of the sentence.

Here, 歩数 is the thing that is doing the reaching:

• 歩数が届く = the step count reaches

So in this sentence, 歩数 is the subject, and が marks it.

A native English speaker may expect something like I reach my target step count, but Japanese often focuses on the thing itself:

• 歩数が目標歩数に届く
  literally, something like the step count reaches the target step count

With 届く, the particle に marks the destination or target point that something reaches.

So:

• 目標歩数に届く = reach the target step count

This is similar to how に can mark a destination in other sentences:

• 学校に行く = go to school
• 駅に着く = arrive at the station

Here, the target step count is treated like the point being reached.

Because 届く is an intransitive verb, not a transitive one.

That means it does not normally take a direct object marked by を.

So you say:

• 目標歩数に届く = reach the target step count

not:

• 目標歩数を届く ❌

A helpful comparison:

• 届く = something reaches / arrives
• 届ける = to deliver something

So:

• 荷物が届く = the package arrives
• 荷物を届ける = deliver the package

In your sentence, the idea is that the step count comes up to the target, so 届く is used with に.

That is one of its common meanings, yes. But 届く is also used more broadly for reaching a point, standard, level, or goal.

So in this sentence, it does not mean that something is being physically delivered. It means:

• to reach
• to come up to
• to attain

This kind of usage is common with goals or benchmarks:

• 目標に届く = reach the goal
• 基準に届く = meet the standard
• 1万歩に届く = reach 10,000 steps

So here 届く is being used figuratively, not physically.

Both can mean to reach, but the nuance is a little different.

• 届く often has the feeling of reaching up to a target or finally getting there
• 達する（たっする） sounds more formal or objective, like to attain or to amount to

For step counts:

• 目標歩数に届く = reach the target step count
  
  • natural in everyday language
• 目標歩数に達する = attain the target step count
  
  • a bit more formal, report-like, or written

So 届く feels very natural if you are talking about daily exercise, an app, or a personal goal.

Because this sentence is just presenting the basic fact with が.

• 歩数が目標歩数に届く。
  focuses on the step count as the subject that reaches the target.

If you used は, the nuance would shift more toward topic/comment:

• 歩数は目標歩数に届く。

That can be grammatical, but it sounds more contrastive or like you are specifically talking about the step count, perhaps in contrast with something else.

For example:

• 消費カロリーは目標に届かないが、歩数は目標歩数に届く。
  The calories burned do not reach the goal, but the step count does.

So が is very natural when simply stating the event.

届く is in the plain non-past form.

In Japanese, the non-past can mean:

• present
• future
• habitual/general

Depending on context, this sentence could mean things like:

• The step count reaches the target step count.
• The step count will reach the target step count.
• The step count reaches the target (in this kind of situation).

Without context, Japanese often leaves that open.

Yes, from an English point of view, it may feel incomplete, but that is very normal in Japanese.

Japanese often omits information that is understood from context. So 歩数 could mean:

• my step count
• today’s step count
• the current step count
• the step count shown in an app/device

The fuller version might be something like:

• 今日の歩数が目標歩数に届く。 = Today’s step count reaches the target.
• 私の歩数が目標歩数に届く。 = My step count reaches the target.

But if the context already makes that clear, Japanese usually leaves it out.

Yes, it is natural, especially in contexts like:

• fitness apps
• health tracking
• goal setting
• daily activity reports

That said, in real usage you might also see shorter or more natural variations depending on the situation:

• 目標歩数に届く = reach the target step count
• 歩数が目標に届く = the step count reaches the goal
• 歩数が目標歩数に達する = the step count attains the target step count

The original sentence is understandable and grammatical, but in actual conversation or app text, Japanese often avoids repeating 歩数 twice if the meaning is already obvious.

Yes, they can, because they refer to different things:

• 歩数 = the actual step count
• 目標歩数 = the target step count

So the logic is:

• actual step count → reaches → target step count

That said, because both contain 歩数, the sentence can feel a little repetitive. Japanese often simplifies it if context allows:

• 歩数が目標に届く。
• 目標歩数に届く。

These may sound a bit smoother in many everyday contexts.

The structure is:

A が B に 届く

where:

• A = the thing that reaches
• B = the point/target reached
• 届く = to reach

So in your sentence:

• 歩数 = the thing that reaches
• 目標歩数 = the target point
• 届く = reaches

That pattern is useful in many other sentences too:

• 売上が目標に届く。
  Sales reach the target.

• 点数が合格ラインに届く。
  The score reaches the passing line.

• 身長が180センチに届く。
  The height reaches 180 cm.