Decimal to Fraction Inches Chart | Convert Decimal Inches to Fractions

Decimal to Fraction Inches Chart

0.375 inches equals 3/8 inch. 0.5625 inches equals 9/16 inch. This chart converts decimal inch values into their nearest standard inch fractions, with millimeter equivalents included. It is part of the reference charts on this site and the reverse companion to the fraction to decimal chart, which handles the opposite direction.

Use this when a calculator, CAD program, digital caliper, or machine readout gives you a decimal and you need to find the matching fraction on a tape measure or in a set of plans.

Use the precision filter above the table to switch between 16ths (general carpentry), 32nds (finish work), and 64ths (machining and fine joinery). For fraction-to-decimal conversions, use the fraction to decimal chart.

How to Convert Decimal Inches to Fractions

Converting a decimal inch value to a fraction takes three steps:

1. Choose your precision. Decide whether you need the nearest 1/16, 1/32, or 1/64 inch. For most construction work, 1/16 is fine. For trim and cabinetry, use 1/32. For machining, use 1/64.
2. Multiply by the denominator. Take your decimal and multiply it by 16, 32, or 64. For example, 0.375 × 16 = 6.
3. Round and simplify. Round the result to the nearest whole number, place it over the denominator, and reduce. 6/16 simplifies to 3/8 inch.

Worked example: Convert 0.42 inches to a fraction to the nearest 1/16 inch. Multiply: 0.42 × 16 = 6.72. Round to 7. The result is 7/16 inch (0.4375). The rounding error is 0.42 − 0.4375 = −0.0175 inch, which is within tolerance for general construction.

Worked example: Convert 0.5625 inches. Multiply: 0.5625 × 16 = 9. No rounding needed. The result is exactly 9/16 inch.

You can skip the math entirely by entering the decimal into the quick converter above or scanning the chart directly.

Rounding Rules for Construction and Woodworking

Rounding is often necessary because real-world decimals do not always land exactly on a tape measure fraction. A CAD dimension might read 2.42 inches, but there is no 0.42-inch mark on a tape. You need a rounding rule to pick the nearest usable fraction.

When rounding matters depends on the project. For framing and rough layout at the 16ths level, a 1/32-inch rounding error is invisible. For trim work at the 32nds level, rounding errors compound across multiple parts — four pieces each rounded by 1/32 inch in the same direction adds up to 1/8 inch of drift by the end of the run.

Follow these practices to keep rounding under control:

• Round up on finished dimensions that must not be undersized. A door opening that is 1/32 inch too wide is easier to shim than one that is too narrow.
• Round down where extra material can be trimmed later. Moulding and trim stock that is slightly long can be cut to fit on site.
• Keep the same rounding rule across all parts in a project. Mixing round-up and round-down within one assembly creates uneven gaps.
• Use finer precision when errors compound. Long runs of flooring, cabinet face frames, and stair stringers all accumulate rounding errors — use 32nds or 64ths for these.

Examples of Decimal to Fraction Conversions

These are decimal values that come up regularly in construction, woodworking, and metalworking:

Example: Your flooring calculator output shows a plank width of 0.1875 inches. Scan the chart — that is exactly 3/16 inch. Set your tape or fence to 3/16.

Example: A caliper reads 0.4219 inches on a drill bit. That is 27/64 inch — a standard fractional drill size used in metalworking.

Related Tools

• Fraction to Decimal Chart — Full interactive conversion chart with 16ths, 32nds, and 64ths views plus a quick converter for any fraction.
• Fraction to Decimal Chart (16ths) — Focused chart for general carpentry where 1/16-inch accuracy is enough.
• Fraction to Decimal Chart (32nds) — Precision chart for finish carpentry and cabinetry.
• Fraction to Decimal Chart (64ths) — High-precision chart for fine woodworking and machining.
• Lumber Dimensions Chart — Look up nominal vs actual lumber sizes where fractional dimensions like 1-1/2” and 3-1/2” are standard.
• Drywall Calculator — Estimate sheets and materials for drywall projects where 1/2” and 5/8” thickness fractions are standard measurements.