300 mm to Inches
Convert 300 millimeters to inches — instant, accurate, and easy
The Answer
Browse tape measures on Amazon.
📄 Free printable mm to inches chart (PDF) — every mm from 1 to 300.
How to Convert 300 mm to Inches
To convert 300 millimeters to inches, divide the millimeter value by 25.4. This is because one inch equals exactly 25.4 millimeters — a standard defined by international agreement.
The Calculation
Applying the formula to 300 mm:
Result Summary for 300 mm
- Decimal inches: 11.8110″
- Fractional inches: 11 13/16″ (nearest 1/64)
- Feet and inches: 0 ft 11.81 in
300 mm Compared With a 12-Inch Ruler
300 mm is 30 cm, or approximately 11.8110 inches. A 12-inch ruler spans exactly 304.8 mm, so 300 mm is 4.8 mm shorter.
The nearest 1/16-inch mark is 11 13/16 inches, representing 300.0375 mm: 0.0375 mm above the original measurement.
That is why a 300 mm metric ruler and a 12-inch ruler look almost the same length but are not interchangeable: over the full length the metric ruler is 4.8 mm (about 3/16 inch) short.
Reading 300 mm on a 12-Inch Ruler
300 mm is 11.8110 inches when rounded to four decimals. The closest common tape mark is 11 13/16 inches; a full 12 inches is 304.8 mm, which is 4.8 mm longer.
Find the Mark Step by Step
Count eleven full inches, then thirteen 1/16-inch divisions. That mark is 11 13/16 inches. The exact 300 mm point sits 0.0375 mm before it.
The Tape Marks on Either Side
| Position | Tape mark | Mark in mm | Difference from 300 mm |
|---|---|---|---|
| Lower 1/16-inch mark | 11 3/4″ | 298.45 mm | −1.55 mm |
| Upper 1/16-inch mark | 11 13/16″ | 300.0375 mm | +0.0375 mm |
Positive differences are longer than 300 mm; negative differences are shorter. These are conversion rounding differences, not the accuracy of a measuring tool.
A Practical Example
A 300 mm template repeated four times spans 1,200 mm. Replacing each span with 12 inches makes the total 1,219.2 mm, an accumulated difference of 19.2 mm.
Check the scale on a ruler before using its full length as a template: 300 mm and 12 inches are different endpoints. Use its marked zero rather than an unmarked physical edge.
For the full method, see how to read inch and millimeter tape markings. For other sizes, use the millimeter-to-inch conversion chart and printable table.
Calculation basis: inches = millimeters ÷ 25.4. NIST defines one inch as exactly 25.4 mm. Decimal results and tape fractions shown here are rounded.
Reference Table — Values Near 300 mm
| Millimeters | Decimal Inches | Fractional Inches |
|---|---|---|
| 297 mm | 11.6929″ | 11 11/16″ |
| 298 mm | 11.7323″ | 11 47/64″ |
| 299 mm | 11.7717″ | 11 49/64″ |
| 300 mm | 11.8110″ | 11 13/16″ |
| 301 mm | 11.8504″ | 11 27/32″ |
| 302 mm | 11.8898″ | 11 57/64″ |
| 303 mm | 11.9291″ | 11 59/64″ |
300 mm in Other Units
Millimeters convert cleanly into every other length unit. Here is 300 mm expressed seven different ways — useful when a drawing, spec sheet or supplier quotes a unit other than inches.
| Unit | 300 mm equals |
|---|---|
| Centimeters (cm) | 30 cm |
| Meters (m) | 0.3 m |
| Inches (in) | 11.8110 in |
| Feet (ft) | 0.9843 ft |
| Yards (yd) | 0.32808 yd |
| Thousandths of an inch (mil) | 11,811 mil |
| Typographic points (1/72 in) | 850.39 pt |
How Accurate Is Each Fraction of 300 mm?
300 mm equals 11.8110″ (rounded to four decimal places). Any fraction is a further rounding of the full-precision value, so each one carries a small error. This table shows the closest fraction at each common denominator and how far it actually sits from 300 mm.
| Rounded to | Fraction | Decimal | Fraction vs. original |
|---|---|---|---|
| Nearest 1/2″ | 12″ | 12.0000″ | +4.800 mm (above original) |
| Nearest 1/4″ | 11 3/4″ | 11.7500″ | −1.550 mm (below original) |
| Nearest 1/8″ | 11 3/4″ | 11.7500″ | −1.550 mm (below original) |
| Nearest 1/16″ | 11 13/16″ | 11.8125″ | +0.038 mm (above original) |
| Nearest 1/32″ | 11 13/16″ | 11.8125″ | +0.038 mm (above original) |
| Nearest 1/64″ | 11 13/16″ | 11.8125″ | +0.038 mm (above original) |
For woodworking, DIY and general workshop use, 11 13/16″ is the practical choice — it lands within 0.4 mm of 300 mm. For machining, toolmaking or CAD, use the decimal value 11.8110″ rather than any fraction.
FAQ About 300 mm to Inches
How many inches is 300 mm?
300 millimeters equals 11.8110 inches (rounded to 4 decimal places), or approximately 11 13/16″ (nearest 1/64 inch).
How accurate is the 300 mm to inches conversion?
The conversion of 300 mm to 11.8110 inches uses the exact definition 1 inch = 25.4 millimeters; the four-decimal result is rounded, so it is approximate.
Can I convert 300 mm to feet?
Yes. 300 millimeters equals approximately 0 ft 11.81 in.
📏 Need to measure 300mm accurately?
A tape measure marked in millimeters covers 300 mm and much more (300 mm ≈ 11.8110″). See current options:
Read our 25ft tape measure buying guide →
As an Amazon Associate, we earn from qualifying purchases at no extra cost to you.