Units & Conversion Factors

LENGTHS

1 inch = 25.4 millimeters

1 meter = 3.28 feet = 39.37 inches

1 mile = 5280 ft = 1760 yards = 1.609 kilometers = 1609 meters

AREAS

1 square inch = 6.45 square centimetres = 645 square millimetres

1 square metre = 10.76 square feet = 1.196 square yards

1 are = 100 square metres = 119.6 square yards

1 hectare = 10,000 square metres = 100 ares = 2.47 acres

1 square kilometres = 100 hectares = 1,00,000 square metres

1 acre = 4840 square yards = 0.4047 hectares

1 square (Gunter's) chain = 484 square yards = 0.1 acres

1 square miles = 640 acres = 2.59 square kilometres

VOLUMES

[There are three different types of gallon used in English speaking world, i.e. Imperial Gallon, Wet US Gallon, Dry US Gallon]

1 cubic feet = 6.24 Imperial Gallon [1 imperial gallon of water weights 10 lb]

1 US wet gallon = 0.833 imperial gallon = 3.785 litres

1 US dry gallon = 0.967 imperial gallon = 4.404 litres

1 imperial gallon = 4.546 litres

1 litre = 0.22 imperial gallon

1 US barrel (bbl.) = 5.62 cubic feet

1 cubic metre = 35.28 cubic feet

1 acre-foot = 43,560 cubic feet = 0.5 cusec-day

WEIGHTS

PRESSURE or STRESS

MISCELLANEOUS

Standard Sieves

Sieves commonly used for sieve analysis of concrete aggregates:

Coarse sieves
75.0 mm 3 in. 75.0 3
63.0 mm 2-1/2 in. 63.0 2.5
50.0 mm 2 in. 50.0 2
37.5 mm 1-1/2 in. 37.5 1.5
25.0 mm 1 in. 25.0 1
19.0 mm 3/4 in. 19.0 0.75
12.5 mm 1/2 in. 12.5 0.5
9.5 mm 3/8 in. 9.5 0.375

Fine sieves
4.75 mm No. 4 4.75 0.1870
2.36 mm No. 8 2.36 0.0937
1.18 mm No. 16 1.18 0.0469
600 μm* No. 30 0.60 0.0234
300 μm No. 50 0.30 0.0117
150 μm No. 100 0.15 0.0059

Finest sieve normally used for aggregates
75 μm No. 200 0.075 0.0029

U. S. Standard Sieve Series

Bureau of Standards Sieve Number	Specified Sieve Opening		Specified Wire Diameter Inches	Tolerances Permitted
	Inches	Microns		Average Opening	Wire Diameter	Maximum Opening
4	.187	4760	.050	+ - 3%	- 15% to + 30%	10%
5	.157	4000	.044	+ - 3%	- 15% to + 30%	10%
6	.132	3360	.040	+ - 3%	- 15% to + 30%	10%
7	.111	2830	.036	+ - 3%	- 15% to + 30%	10%
8	.0937	2380	.0331	+ - 3%	- 15% to + 30%	10%
10	.0787	2000	.0299	+ - 3%	- 15% to + 30%	10%
12	.0661	1680	.0272	+ - 3%	- 15% to + 30%	10%
14	.0555	1410	.0240	+ - 3%	- 15% to + 30%	10%
16	.0469	1190	.0213	+ - 3%	- 15% to + 30%	10%
18	.0394	1000	.0189	+ - 3%	- 15% to + 30%	10%
20	.0331	840	.0165	+ - 5%	- 15% to + 30%	25%
25	.0280	710	.0146	+ - 5%	- 15% to + 30%	25%
30	.0232	590	.0130	+ - 5%	- 15% to + 30%	25%
35	.0197	500	.0114	+ - 5%	- 15% to + 30%	25%
40	.0165	420	.0098	+ - 5%	- 15% to + 30%	25%
45	.0138	350	.0087	+ - 5%	- 15% to + 30%	25%
50	.0117	297	.0074	+ - 6%	- 15% to + 35%	40%
60	.0098	250	.0064	+ - 6%	- 15% to + 35%	40%
70	.0083	210	.0055	+ - 6%	- 15% to + 35%	40%
80	.0070	177	.0047	+ - 6%	- 15% to + 35%	40%
100	.0059	149	.0040	+ - 6%	- 15% to + 35%	40%
120	.0049	125	.0034	+ - 6%	- 15% to + 35%	40%
140	.0041	105	.0029	+ - 8%	- 15% to + 35%	60%
170	.0035	88	.0025	+ - 8%	- 15% to + 35%	60%
200	.0029	74	.0021	+ - 8%	- 15% to + 35%	60%
230	.0024	63	.0018	+ - 8%	- 15% to + 35%	90%
270	.0021	53	.0016	+ - 8%	- 15% to + 35%	90%
325	.0017	44	.0014	+ - 8%	- 15% to + 35%	90%

Types of Loads in Structures

• Dead Loads
The dead load includes loads that are relatively constant over time, including the weight of the structure itself, and immovable fixture.
• Live Loads
Live loads are temporary, of short duration, or moving.
• Dynamic Loads (equipments)
Loads due to vibration of equipments, machines, railways etc.
• Wind Loads
• Snow & ice Loads
• Earthquake/Siesmic Loads
• Thermal Loads
• Settlement Loads etc.