Here we presenting you detailed estimate formulas and some use ful informations.

Construction Estimating Formulas & Useful Information

Formulas, equations, tables, facts, specifications and other 
information useful in planning and estimating construction, 
decorating and other projects.

 Measure of Dimensions, Theorem ▪   Formulas, Rectangles, Squares, Triangles & Circles ▪  Board Feet Concrete Estimating ▪ Decimal and Metric Equivalents ▪  Weights, etc. ▪  Metrics ▪  Energy, Electric, Insulation ▪ Drywall Estimating,  Door Handing

Three dimensions of estimating:

Linear Measure	Square Measure	Cubic Measure
12 inches = 1 lineal ft.	12" x 12" = 144sq" = 1sq ft.	12" x 12" x 12" = 1728 cu" = 1 cubic ft.
3 lineal feet = 1 yard.	3' x 3' = 9sq feet = 1sq yd.	3' x 3' x 3' = 27 cu feet = 1 cubic yard.
5,280 lin ft = 1 mile.	43,560sq' = 1 acre.	36" x 36" x 36" = 46,656 cu" = 1 cubic yard.
Inches x .0833 = ft. Inches / 12 = ft.	Sq" x .00694 = sq ft.	Cu" x .0005787 = cu'.
Inches x .2778 = yds.	Sq" x .007716 = sq yds.	Cu' x .0002143 = cu yds.
Feet x .3333 = yds.	Sq' x .11111 = sq yds.	Cu' x .03704 = cu yds.
	100sq feet = 1 square (measure used in roofing).

Useful Mathematical Formulas:

1. One of the most useful formulas is the Pythagorean theorem.  The theorem states that the square of the hypotenuse of a right (90 degree angle) triangle is equal to the sum of the squares of its legs.

For Example:        (3' x 3' = 9') + (4' x 4' =16') = 25',  √25=5

This can be used for a wide variety of uses from squaring up a concrete form for a foundation, to attaching a new addition squarely to an existing building, or measuring a countertop -anywhere you must be certain of a right angle.  Just plug in your numbers and get a calculator that has a square root function.

                                                                                              

2.  The area of a rectangle is equal to its base x height. (A = b x h).

For example:     10 x 5 = 50

3.  The area of a square is equal to its base x height (see above).
               -or-
  The area of a square is equal to the square of one of its sides. (A = S squared).

For example:     5²=25

4.  The area of a triangle is equal to 1/2 the product of its base and height. A = 1/2 (b x h).

For example:     10 x 10 = 100 x 1/2 = 50

5.  Circles

The area of a circle is equal to 1/2 the product of its radius and circumference. (A = 1/2 (r x c). 

For example:            radius = 5, circumference = 31.42:   5 x 31.42 = 157.1 x 1/2 = 78.55

 -or-

                                A=π r², 3.1416(5 x 5) = 3.1416 x 25 = 78.54

-or-

A= d² x .7854

Find the circumference of a circle by multiplying the diameter x (π).  Find the volume of a cylinder by multiplying the height x the area of the circle.

*π = 3.1416

The circumference of a circle can be divided into equal parts with a calculator.  This will allow you to make proportioned shapes within the circle.  For example -stars, triangles, octagons, etc.

To find the divisions, multiply the diameter of the circle by the following multipliers.

Division	Multiplier		Division	Multiplier
3	.86603		8 (Octagon)	.38268
4	.70711		9	.34202
5	.58779		10	.30902
6	.50000		11	.28173
7	.43388		12	.25882

For example:

21.166" x .38268 (from above table) = 8.099"

6.  Board Feet:  A board foot is essentially a measure of wood, figured on the called size, not the actual finished size.  Therefore a 2" x 4" x 8" contains 5.33 bd. ft.  The theory is that you pay for what the mill started with before the wood is dried and planed.

    Thickness" x Width" x Length in feet, divided by 12 = board feet. T" x W" x L" ÷ 12 = Board ft.

    Thickness" x Width" x Length in inches divided by 144 = bd. ft. (T" x W" x L") ÷ 144 = Board ft.

7.  Concrete:  Concrete is usually measure in cubic yards.  A cubic yard is 3' wide x 3' long x 3' thick.  3' x 3' x 3' = 27 cubic feet.  27 cubic feet = 1 cubic yard.

The formula is:  L' x W' x T' ÷ 27 = cubic yards.
                        -or-
                        L' x W' x T" ÷ 12 ÷27 = cubic yards (where T is in inches).
                        -or-
                        L" x W" x T" ÷ 1728 ÷ 27 = cubic yards (where L, W, T, are in inches).

One cubic yard covers 324 square feet at 1" thickness.

One cubic yard is equal to approximately 40 bags of 80 pound concrete mix (+/- .675 cu' per bag).

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The table below shows how many (approx.) 80 pound bags of concrete mix it will take to fill these tubes used to construct concrete piers, etc.

Diameter of tube	Approx. number of 80 pd. bags	To fill this many feet
6"	1 bag	3 feet
8"	1 bag	2 feet
10"	1-1/2 bags	2 feet
12"	2-1/2 bags	2 feet
14"	1-1/2 bags	1 foot
30"	7-1/2 bags	1 foot
Formula: Diameter squared x .7854 x height.  For example 30" x 30" x .7854 = 706.86 ÷144 (to convert from cubic inches to cubic feet) = 4.91 cu. ft. ÷ .675 cu. ft. per bag = 7.27 bags (rounded to 7-1/2).

One 80 pound bag of concrete mix will cover an area approximately 2' x 4' x 1'.

Decimal and Millimeter equivalents of fractions of an inch.

Inches	Inches	Mm		Inches	Inches	Mm
1/64	.01563	.397		33/64	.51563	13.097
1/32	.03125	.794		17/32	.53125	13.494
3/64	.04688	1.191		35/64	.54688	13.890
1/16	.0625	1.587		9/16	.5625	14.287
5/64	.07813	1.984		37/64	.57813	14.684
3/32	.09375	2.381		19/32	.59375	15.081
7/64	.10938	2.778		39/64	.60938	15.478
1/8	.125	3.175		5/8	.625	15.875
9/64	.14063	3.572		41/64	.64063	16.272
5/32	.15625	3.969		21/32	.65625	16.669
11/64	.17188	4.366		43/64	.67188	17.065
3/16	.1875	4.762		11/16	.6875	17.462
13/64	.20313	5.159		45/64	.70313	17.859
7/32	.21875	5.556		23/32	.71875	18.256
15/64	.23438	5.953		47/64	.73438	18.653
1/4	.250	6.350		3/4	.750	19.050
17/64	.26563	6.747		49/64	.76563	19.447
9/32	.28125	7.144		25/32	.78125	19.844
19/64	.29688	7.541		51/64	.79688	20.240
5/16	.3125	7.937		13/16	.8125	20.637
21/64	.32813	8.334		53/64	.82813	21.034
11/32	.34375	8.731		27/32	.84375	21.431
23/64	.35938	9.128		55/64	.85938	21.828
3/8	.375	9.525		7/8	.875	22.225
25/64	.39063	9.922		57/64	.89063	22.622
13/32	.40625	10.319		29/32	.90625	23.019
27/64	.42188	10.716		59/64	.92188	23.415
7/16	.4375	11.113		15/16	.9375	23.812
29/64	.45313	11.509		61/64	.95313	24.209
15/32	.46875	11.906		31/32	.96875	24.606
31/64	.48438	12.303		63/64	.98138	25.003
1/2	.500	12.700		1	1.0000	25.400

Formula: 1 divided by the fraction = thousands of an inch.  For example: 1 ÷ 4 = .250

Weights, Measures, and Miscellaneous information.

Doubling the diameter of a pipe increases its capacity four times.

A gallon of water weights 8.336 pounds at 39 degrees Fahrenheit (point of greatest density).

A gallon of water contains 231 cubic inches.

One cubic foot equals 1,728 inches.

One cubic foot of water equals 7-1/2 gallons.

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Weight of some common building materials.

Approximate weights of dry wood by cubic foot (not board foot).
Ash	3-3/4		Red  Oak	3-3/4
Birch	3-3/4		White Oak	4
Cedar	3-1/4		White Pine	2-1/3
Hemlock	2		Yellow Pine	3
Hickory	4		Poplar	2-1/2
Maple	3-1/2		Spruce	2-1/3

Metals: Approximate weights per cubic foot, In pounds.
Brass	518		Copper	550
Cast Iron	450		Lead	710
Forged Steel	490		Tin	458
Aluminum	167

Concrete with Stone Pounds per cu. ft. approx.	150	Loose Earth Pounds per cu. ft. approx.	76	Dry Sand Pounds per cu. ft. approx.	100
Frame wall with  1/2" drywall ppsf.	12	Floor sys 1/2" plywood with 3/4" flr. ppsf.	6	Roof Joist 1/2" plywood ppsf.	3
Cell Joist 1/2" drywall ppsf.	7	Glass 1/8" ppsf.	1.63	Glass 1/8" IG ppsf	3.25

Metrics:

25.4 millimeter equals 1 inch.
2.54 centimeters equals 1 inch.
1 meter equals 39.37 inches.
1.6 kilometer equals 1 mile.
100 millimeter equals 1 centimeter
100 centimeter equals 1 meter
100 meter equals 1 kilometer

Approximate Conversions:

Inches	x	25=	Mm		Mm mm	x ÷	0.04= 25.4=	Inches Inches
Inches	x	2.5=	Cm		Cm Cm	x ÷	0.4= 2.54=	Inches Inches
Feet	x	30=	Cm		Meter	x	3.3=	Feet
Yards	x	0.9=	Meter		Meter	x	1.1=	Yards
Meter	x	1.6=	Kilometer		Kilometer Kilometer	x ÷	0.6= 1.6=	Miles Miles

Temperature
Celsius	Fahrenheit
-30	-22
-20	-4
-10	14
0	32
10	50
20	68
30	86
40	104
50	122

Temperature Formula:  °Fahrenheit - 32 x 0.56 = °Celsius

                                    °Celsius x 1.8 + 32 = °Fahrenheit

Liquid:
1 ounce = 29.57 milliliters
1 quart = 0.95 liter
1 gallon = 3.79 liters

Cord Wood:

 A cord of wood measures 4' x 4' x 8'.  Stacked cord contains 128 cubic feet by measure.  Actually is 80 cubic feet -the rest is air.
Weighs 3,000 pounds when dry, 4,000 pounds when wet. Seasoned wood is defined as having 25% moisture content.  Four percent of its energy is lost in the evaporation process as it burns.  Green wood is defined as having 80% moisture content.  Fifteen percent of its energy is lost in the evaporation process.

Fuel energy BTU comparison:

Heating Oil	138,000 BTU per gallon (number 2 fuel oil)
Natural Gas	100,000 BTU per therm
L P gas	93,000 BTU per gallon
Mixed Hardwood	8,600 BTU per pound based on seasoned wood weighing +/- 3,000 pd. per cord.  24,000,000 BTU per cord (+/-)

Electrical formulas:  1.  Amps = Watts / Volts
                                     2.  Watts = Amps x Volts
                                     3.  Volts = Watts / Amps

Insulation:  The R-value of materials measures its resistance to heat flow.  The higher the R value, the better the resistance to heat flow.
                 The U-value is used to calculate heat loss.
Formula to find U-value is:  1 / R - value = U - value.

R-values of some common building materials:

1" Fiberglass batt, Insulation	3.17		1" Expanded polystyrene	4.00		1" Extruded polystyrene	5.0
1" Polyisocyanurate, foil-faced	7.20		8" concrete block	1.11		1' Poured concrete	0.08
1" Soft wood lumber	1.25		2x4 kds	4.38		2x6 kds	6.88
1/2" plywood	0.63		3/4" plywood	0.94		1/2" gypsum board	0.45
Window with  single glass	0.91		Windows with IG glass 1/4" air sp.	1.69		Windows with 1/2" Low E IG	3.13
Wood solid core 1-3/4 door	3.03		Metal ins. door no glass	15.00		1/2" - 4" air space	1.00

                      

Temperature Formula:  Degrees Fahrenheit - 32 x 0.56 = degrees Celsius

                                    Degrees Celsius x 1.8 + 32 = Degrees Fahrenheit

Liquid:
1 ounce = 29.57 milliliters
1 quart = 0.95 liter
1 gallon = 3.79 liters

Drywall board installation: Approximate quantities needed for each item per 1,000' of wall to cover.
32 pcs. 4 x 8 panels or 25 pcs. 4 x 10 or 21 pcs. 4 x 12.
138 pounds of ready mix compound.
370 lineal feet of tape.
2,000 nails or 1,275 screws.
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How to determine the handing of an interior passage or closet door.
Face the door on the side of the door where in order to pen the door you must pull it toward you.  If the door knob is on the right it is a right hand operating door.  If the door knob is on the left it is a left hand operating door.
Exterior doors are identified in the same way, but it is also necessary to state that the door is an inswing (swings into the building) or an outswing (swings to the outside of the building).
The active door of a Double door will also need to be identified -usually this is done by viewing the door from the outside.  It is either a left active or right active panel.
It is also wise to check with the manufacturer or sales person before ordering to make sure that they do it the same way.
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Miscellaneous Math:
1.  Doubling a fraction makes it 1/2 its size.
For example:  2 x 1/16" = 1/32" and 2 x 1/4" = 1/8".
To calculate the angles of multisided objects:

Divide 360 by the number of sides and ÷ by 2.
For example:  An octagon -divide 360 by 8 (the number of sides) = 45 (the center angle) ÷ by 2 = 22-1/2 (the other 2 angles).




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