Портной подогнал выкройку по меркам.

Because выкройка is a feminine noun, and here it is the direct object of the verb подогнал.

• Dictionary form: выкройка
• Accusative singular: выкройку

In Russian, feminine nouns ending in -а usually change to -у in the accusative singular when they are direct objects.

So:

• Портной = the subject
• подогнал = the action
• выкройку = the thing being adjusted

Because the preposition по here requires the dative case, and меркам is the dative plural of мерка.

• Dictionary form: мерка = a measurement
• Dative plural: меркам

So по меркам means something like:

• according to the measurements
• based on the measurements

This is a very common pattern:

• по плану = according to the plan
• по правилам = according to the rules
• по рецепту = according to the recipe

Here подогнал means adjusted or made fit.

The verb подогнать often means:

• to adjust something so it fits
• to tailor something to match something else
• to make something conform to certain measurements or requirements

In this sentence, it means the tailor adjusted the pattern so it matched the measurements.

It does not mean simply drove up here, even though подогнать can have other meanings in other contexts.

Because Russian past tense verbs agree with the subject in gender and number.

The subject is портной, which is masculine singular, so the past tense form is:

• подогнал = masculine singular

Compare:

• Портной подогнал... = masculine
• Портниха подогнала... = feminine
• Они подогнали... = plural

Подогнал is perfective.

That means the sentence presents the action as completed: the tailor finished adjusting the pattern.

The verb pair is:

• подгонять = imperfective
• подогнать = perfective

So:

• Портной подгонял выкройку... = the tailor was adjusting / used to adjust the pattern
• Портной подогнал выкройку... = the tailor adjusted the pattern, successfully completing the action

This is why подогнал sounds natural if you are describing a finished result.

No. Выкройка is not the finished piece of clothing.

It means a pattern used for cutting fabric. In sewing, it is the template or shape that helps you cut the material correctly.

So the sentence is about adjusting the pattern, not necessarily the final garment.

They are related, but not the same.

• мерка = a measurement taken from a person or object
  For example: chest, waist, sleeve length
• размер = size
  For example: shoe size, clothing size, dimensions

In tailoring, по меркам is especially natural because a tailor works from actual body measurements.

So this sentence uses exactly the right word for the context.

Because Russian has no articles like the or a/an.

So Портной can mean:

• the tailor
• a tailor

Which one sounds right depends on context and the translation you were given.

Russian usually relies on context, word order, and the situation instead of articles.

Yes. Russian word order is flexible, because case endings already show the grammatical roles.

The neutral order here is:

• Портной подогнал выкройку по меркам.

But other orders are possible, for example:

• Выкройку по меркам подогнал портной.
• По меркам портной подогнал выкройку.

These may sound more emphatic or stylistically different, but the basic meaning stays the same.

Literally, it is something like by the measurements or according to the measurements.

In English, a natural translation is usually:

• according to the measurements
• to match the measurements

So the phrase is not about location or movement. It tells you the basis on which the pattern was adjusted.

Yes. По меркам can also mean by the standards of.

For example:

• По современным меркам это дорого. = By modern standards, this is expensive.

So the phrase has a broader meaning in Russian, but in a tailoring sentence it clearly refers to actual physical measurements.

The main stresses are:

• портнОй
• подогнАл
• выкрОйку
• мЕркам

So roughly:

портнОй подогнАл выкрОйку по мЕркам

Stress matters in Russian, so it is worth learning words together with their stress.

Yes, портной is a masculine noun, so it usually refers to a male tailor.

For a female tailor, you might see:

• портниха
• sometimes швея, though that is more like seamstress / dressmaker / someone who sews

So if the subject were female, the sentence would change to:

• Портниха подогнала выкройку по меркам.

Usually по меркам in the plural is more natural when talking about tailoring, because clothing patterns are based on multiple measurements.

A person normally has many relevant measurements:

• chest
• waist
• hips
• sleeve length
• inseam

So по меркам is the expected phrase here.

The singular по мерке can exist, but it would usually refer to one specific measurement or be used in a different phrasing. In clothing contexts, the plural is much more idiomatic.