Exact inch to millimeter reference

5/8 inch to mm: 15.8750 mm

Convert 5/8 inch to millimeters for CNC setup sheets, drawings, inspection notes, and supplier communication. The formula uses the exact international inch standard.

Answer first

5/8 inch =

15.8750 mm

2 decimals
15.88
3 decimals
15.875
4 decimals
15.8750

Answer first: 5/8 inch equals 15.8750 mm

5/8 inch equals 15.8750 mm using the exact conversion factor 1 inch = 25.4 mm. In decimal-inch form, 5/8 inch is 0.625 inch, so the calculation is 0.625 × 25.4 = 15.8750 mm. Use this page as a manufacturing-oriented reference for drawings, setup sheets, inspection notes, supplier communication, and metric documentation. Because 5/8 inch is a fraction, keep the fraction and the decimal-inch form 0.625 inch visible when the value moves into a metric note. The conversion is exact, but it does not decide tolerance, fit, stock availability, material equivalence, replacement approval, or process capability.

Formula and precision policy

mm = inch × 25.4 → 0.625 × 25.4 = 15.8750 mm

Formula: millimeters = inches × 25.4. For this page, 0.625 inch × 25.4 = 15.8750 mm. Keep 15.8750 mm when mating clearance is discussed; rounded 15.88 mm notes should still carry the original 5/8 in callout. The same result can also be shown as 15.88 mm, 15.875 mm, or 15.8750 mm depending on the receiving document. Those displays are rounding choices, not manufacturing instructions. Use the drawing tolerance block, limit dimension, process plan, inspection method, or supplier specification to decide how many digits belong in production paperwork. Never use the rounded conversion alone as proof that a feature is within tolerance or approved for substitution.

Equivalent forms

Where this value appears in manufacturing work

  • 5/8 inch commonly shows up in larger spacers, plate widths, bracket offsets, and clearance planning around assemblies; the converted 15.8750 mm value is the unit reference, not the whole production instruction.
  • A 5/8 inch offset can be a design clearance in an assembly, not an instruction to buy a standard component with that name. A strong shop note writes 5/8 inch (0.625 in) = 15.8750 mm reference before adding feature type, tolerance, material, or inspection details.
  • Use the conversion to prevent arithmetic and transcription errors, but do not use it to decide assuming the fraction identifies a fastener, drill, thread, wrench, replacement part, or metric standard size.
  • For this page-specific manufacturing hook, treat the work artifact as a assembly clearance review note; record the drawing revision, source units, and process stage beside the metric value.
  • 5/8 assembly-clearance dimension with mating-part risk This is why 5/8 inch should keep its original inch notation even when downstream paperwork is metric.
  • If a supplier proposes a nearby metric item or a rounded substitute, treat that proposal as a separate review step rather than as a conclusion from 15.8750 mm alone.

When to keep exact decimals vs rounded values

Keep 15.8750 mm when mating clearance is discussed; rounded 15.88 mm notes should still carry the original 5/8 in callout. Keep 15.8750 mm when the converted value is copied into a calculation sheet, QA record, CNC setup note, or RFQ where traceability matters. A shorter display such as 15.88 mm may be readable, but it can hide the source notation and the rounding step. For 5/8 inch, the safer documentation pattern is: 5/8 inch (0.625 in) = 15.8750 mm reference; see the drawing or process plan for tolerance and usage. This keeps the exact conversion separate from engineering decisions, supplier proposals, and shop-floor adjustments.

Measurement and inspection notes

  • For assembly clearances near 5/8 inch, inspect the assembled condition or datum scheme specified by the drawing rather than only the converted standalone dimension.
  • For 5/8 inch, first identify whether the feature is a thickness, outside dimension, inside dimension, hole, slot, center distance, spacing, or reference note.
  • The exact conversion to 15.8750 mm does not define pass/fail criteria; those come from the drawing, tolerance block, inspection plan, or approved supplier document.
  • A caliper, micrometer, gauge pin, indicator, CMM routine, or fixture check can produce different confidence levels for the same converted number.
  • Record the original inch value beside the metric value when inspection data must be traceable across inch-based and metric documents.
  • Do not infer calibration intervals, certified accuracy, or process capability from this conversion page.

CNC and shop-floor setup notes

  • When programming offsets around 5/8 inch, check datums, work offsets, and fixture orientation before entering 15.8750 mm into a metric setup.
  • Before entering 15.8750 mm into a CNC setup sheet, confirm whether the program, controller, CAM post, drawing, and operator notes are using inch or metric units.
  • If the job is metric on the machine but inch-based in the drawing, show both 5/8 inch and 15.8750 mm so the operator can trace the value back to the source.
  • Keep cutter compensation, kerf, stock-to-leave, coating, grinding allowance, finishing allowance, and probing offsets as separate labeled fields.
  • Do not silently add or subtract process allowance from the converted value; any adjustment should be visible in the traveler, setup note, or NC documentation.
  • Check G20/G21 mode, CAM/post-processor units, and setup-sheet rounding before cutting, probing, or releasing inspection paperwork.

Supplier, drawing, and RFQ communication notes

  • Supplier notes should tie 5/8 in to a named offset, spacer, or plate feature and state whether mating-part clearance is reference-only.
  • A clear supplier line can read: 5/8 inch (15.8750 mm reference), use the drawing revision and stated tolerance for acceptance.
  • Include material callout, finish requirement, drawing revision, inspection requirement, and whether the metric number is reference-only or a required converted working dimension.
  • Do not send only the rounded millimeter value when the design authority is inch-based, because the supplier may lose the source notation and rounding context.
  • If the supplier suggests a nearby stock size, standard item, or substitute, require separate engineering, purchasing, or drawing-owner review.
  • Use the conversion as communication support, not as a replacement approval, material equivalence statement, compliance claim, or supplier certification.

Mistakes to avoid with 5/8 inch to mm

  • Do not assume 5/8 inch identifies a metric fastener, drill, thread, wrench, stock item, or replacement component.
  • Do not drop the decimal-inch form 0.625 inch when the fraction is copied into CAD, QA, or RFQ notes.
  • Do not infer load rating, spacer approval, or replacement suitability from the 15.8750 mm conversion.
  • Do not treat 15.8750 mm as a tolerance-controlled size without the controlling drawing or inspection plan.
  • Do not remove 5/8 inch from a supplier message when the source drawing or note is inch-based.
  • Do not confuse display precision with manufacturing precision, process capability, or acceptance criteria.
  • Do not treat a nominal fraction as proof of interchangeability with a nearby metric size.

Reference-only caveat

A 5/8 inch value can be found in material and hardware contexts. Keep drawing notes, finish allowance, and supplier tolerances separate from the unit conversion.

Reference-only caveat: this conversion does not certify tolerance, fit, pressure, load, code compliance, material equivalence, replacement approval, or interchangeability. Confirm the controlling drawing, standard, supplier data, inspection requirement, and engineering approval before manufacturing or substituting parts.

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