Decimal & Metric Conversions
Quick conversions a framer reaches for on every job: fractional inches to decimal, sixteenths to thirty-seconds, and customary to metric. The lookup tables that live in the back of every Blue Book.
After reading
Convert any common fraction (8ths, 16ths, 32nds, 64ths, 7ths, 6ths) to decimal in one glance, and convert any customary measurement (inches, feet, yards, square feet) to or from metric (mm, cm, m, sq m).
Fractions in three resolutions
Framers cut to sixteenths; finish carpenters cut to thirty-seconds; cabinetmakers cut to sixty-fourths. The table below covers all three plus eighths, all in decimal so the values map directly to a tape with both rules.
Decimal Equivalents of 8ths, 16ths, 32nds, 64ths
Decimal Equivalents, Section 1 (1/64 to 21/32)
Rows
21
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Decimal Equivalents, Section 2 (11/32 to 21/32)
Rows
21
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Decimal Equivalents, Section 3 (43/64 to 63/64)
Rows
21
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
Fraction
- Decimal
The seven and the six
When a rule divides odd: 7ths come up in stair stringer math; 6ths and 12ths come up in degree conversions. The table covers all of them.
Decimal Equivalents of 7ths, 14ths, and 28ths
Decimal Equivalents of 7ths, 14ths, and 28ths
Rows
14
7th
,- 14th
- ,
- 28th
- Decimal
- .035714
- 7th
- ,
- 14th
- ,
- 28th
- Decimal
- .535714
7th
,- 14th
- 28th
- ,
- Decimal
- .071429
- 7th
- ,
- 14th
- ,
- 28th
- ,
- Decimal
- .571429
7th
,- 14th
- ,
- 28th
- Decimal
- .107143
- 7th
- ,
- 14th
- ,
- 28th
- Decimal
- .607143
7th
- 14th
- ,
- 28th
- ,
- Decimal
- .142857
- 7th
- ,
- 14th
- 28th
- ,
- Decimal
- .642857
7th
,- 14th
- ,
- 28th
- Decimal
- .178571
- 7th
- ,
- 14th
- ,
- 28th
- Decimal
- .678571
7th
,- 14th
- 28th
- ,
- Decimal
- .214286
- 7th
- ,
- 14th
- ,
- 28th
- ,
- Decimal
- .714286
7th
,- 14th
- ,
- 28th
- Decimal
- .25
- 7th
- 14th
- ,
- 28th
- Decimal
- .75
7th
,- 14th
- ,
- 28th
- ,
- Decimal
- .285714
- 7th
- ,
- 14th
- ,
- 28th
- ,
- Decimal
- .785714
7th
- 14th
- ,
- 28th
- Decimal
- .321429
- 7th
- ,
- 14th
- 28th
- Decimal
- .821429
7th
,- 14th
- ,
- 28th
- ,
- Decimal
- .357143
- 7th
- ,
- 14th
- ,
- 28th
- ,
- Decimal
- .857143
7th
,- 14th
- 28th
- Decimal
- .392857
- 7th
- ,
- 14th
- ,
- 28th
- Decimal
- .892857
7th
,- 14th
- ,
- 28th
- ,
- Decimal
- .428571
- 7th
- 14th
- 28th
- ,
- Decimal
- .928571
7th
,- 14th
- ,
- 28th
- Decimal
- .464286
- 7th
- ,
- 14th
- ,
- 28th
- Decimal
- .964286
7th
,- 14th
- 28th
- ,
- Decimal
- .5
- 7th
- ,
- 14th
- ,
- 28th
- ,
- Decimal
- ,
Decimal Equivalents of 6ths, 12ths, and 24ths
Decimal Equivalents of 6ths, 12ths, and 24ths
Rows
11
6th
,- 12th
- ,
- 24th
- Decimal
- .041667
- 6th
- ,
- 12th
- ,
- 24th
- Decimal
- .541666
6th
,- 12th
- 24th
- ,
- Decimal
- .083333
- 6th
- ,
- 12th
- ,
- 24th
- ,
- Decimal
- .583333
6th
,- 12th
- ,
- 24th
- Decimal
- .125
- 6th
- ,
- 12th
- 24th
- Decimal
- .625
6th
- 12th
- ,
- 24th
- ,
- Decimal
- .166666
- 6th
- ,
- 12th
- ,
- 24th
- ,
- Decimal
- .666666
6th
,- 12th
- 24th
- Decimal
- .208333
- 6th
- ,
- 12th
- ,
- 24th
- Decimal
- .708333
6th
,- 12th
- ,
- 24th
- ,
- Decimal
- .25
- 6th
- 12th
- ,
- 24th
- ,
- Decimal
- .75
6th
,- 12th
- ,
- 24th
- Decimal
- .291666
- 6th
- ,
- 12th
- 24th
- Decimal
- .791666
6th
- 12th
- ,
- 24th
- ,
- Decimal
- .333333
- 6th
- ,
- 12th
- ,
- 24th
- ,
- Decimal
- .833333
6th
,- 12th
- 24th
- Decimal
- .375
- 6th
- ,
- 12th
- ,
- 24th
- Decimal
- .875
6th
,- 12th
- ,
- 24th
- ,
- Decimal
- .416666
- 6th
- 12th
- ,
- 24th
- ,
- Decimal
- .916666
6th
,- 12th
- ,
- 24th
- Decimal
- .458333
- 6th
- ,
- 12th
- 24th
- Decimal
- .958333
Customary to metric
Two tables: customary to metric (inches → mm, feet → m, sq ft → sq m), then metric to customary going the other way. Multiply by the listed factor.
The Metric System of Measurement
Measures of Length
- 1 Millimeter (mm.) = 0.03937079 inch, or about 1/25 inch
- 10 Millimeters = 1 Centimeter (cm.) = 0.3937079 inch
- 10 Centimeters = 1 Decimeter (dm.) = 3.937079 inch
- 10 Decimeters = 1 Meter (m.) = 39.37079 inches, 3.2808992 feet, or 1.09361 yards
- 10 Meters = 1 Decameter (Dm.) = 32.808992 feet
- 10 Decameters = 1 Hectometer (Hm.) = 19.927817 rods
- 10 Hectometers = 1 Kilometer (Km.) = 1093.61 yards, or 0.6213824 mile
- 10 Kilometers = 1 Myriameter (Mm.) = 6.213824 miles
- 1 inch = 2.54 cm., 1 foot = 0.3048 m., 1 yard = 0.9144 m., 1 rod = 0.5029 Dm.
- 1 mile = 1.6093 Km.
On the other hand, if you know the metric measurement and want to know what it would be in the units that are familiar to you, you can multiply by the following conversion factors:
Customary to Metric Conversion Factors
Rows
3
When you know
- Multiply by
- To
- centimeters
When you know
- Multiply by
- To
- centimeters
When you know
- Multiply by
- To
- meters
Metric to Customary Conversion Factors
Rows
5
When you know
- Multiply by
- To Find
- inches
When you know
- Multiply by
- To Find
- inches
When you know
- Multiply by
- To Find
- feet
When you know
- Multiply by
- To Find
- yards
When you know
- Multiply by
- To Find
- miles
Roof Pitch Reference
Convert between rise / run, pitch fraction (1/4, 1/3, 1/2, full), angle in degrees, and rafter length per foot of run for any pitch from 1/12 to 24/12.
RaftersCutting a Common Rafter
Lay out a common rafter from rise + run + length, with the right plumb cut at the ridge and the right tail cut at the eave.