By the TheJobCalc editorial team · Updated September 3, 2026
Every estimating constant used on this site, on one page. Print it, stick it in
the truck, and use the calculators when the numbers need to be exact.
Conversions that run everything
1 of this
equals
Cubic yard
27 cu ft — a 3 ft cube
Square foot
144 sq in
Square yard
9 sq ft
Roofing square
100 sq ft = 3 bundles of shingles
Acre
43,560 sq ft
Inches on the tape
Decimal feet
3 in
0.25 ft
4 in
0.333 ft
6 in
0.5 ft
8 in
0.667 ft
9 in
0.75 ft
What one cubic yard covers
Spread at
2 in
3 in
4 in
6 in
Coverage
162 sq ft
108 sq ft
81 sq ft
54 sq ft
Concrete
Bag
Yield
Bags per cu yd
80 lb
0.60 cu ft
45
60 lb
0.45 cu ft
60
50 lb
0.375 cu ft
72
40 lb
0.30 cu ft
90
Slab thickness: 4 in patios and walks · 5–6 in driveways · 6–8 in
heavy vehicles. Solo bag-mixing limit: about half a cubic yard — past that, call the
ready-mix plant. Foot traffic after 24–48 h; full cure about 28 days.
Gravel, soil and mulch weight
Material
lb per cu yd
Crusher run
3,000
Crushed stone #57
2,800
Pea gravel / river rock
2,700
Bedding sand
2,600
Topsoil
2,200
Shredded hardwood mulch
800
Mulch depth: 2–3 in new bed, 1–2 in top-up. One yard = 13.5 standard 2 cu ft
bags. Paver base: exactly 1 in of bedding sand over 4 in of gravel (8–12 in for
driveways).
Paint and drywall
Rule
Figure
Smooth repaint coverage
350–400 sq ft per gal
Bare drywall (prime first)
200–250 sq ft per gal
Deduct per door / per window
21 / 15 sq ft
Drywall screws
~1 per sq ft of board, 320 per lb
Joint compound
~1 gal per 100 sq ft
Joint tape
~0.4 lf per sq ft
Roof
Roof area = footprint × slope factor, where slope factor =
√(1 + (rise ÷ 12)²):
Pitch
4/12
6/12
8/12
12/12
Slope factor
1.054
1.118
1.202
1.414
Shingle waste: 10% simple gable, 15% hips and valleys.
Framing, fences, decks and stairs
Rule
Figure
Stud / joist spacing
16 in o.c. standard, 24 in light duty
Fence post depth
1/3 of fence height, 24 in minimum, below frost line
Post hole width
3 × the post width; 4–6 in gravel below
Deck board gap
1/8–1/4 in dry lumber; wet PT laid tight
Deck screws
2 per board-joist crossing, ~75 per lb
Stair riser / tread limits
7-3/4 in max riser, 10 in min tread
Stair comfort rule
2 × riser + tread = 24–25 in
Stringers, 36 in stair
3 with 2x treads; 4–5 with composite
Tile and sod
Rule
Figure
Tile waste
10% straight lay · 15% diagonal · 20% herringbone
Effective tile size
(width + joint) × (length + joint)
Sod pallet
~450 sq ft (farms range 400–500), 1,500–3,000 lb
Sod shelf life
Lay within ~24 hours of harvest
Pay math
Rule
Figure
Full-time hours per year
2,080 (40 h × 52 wk)
Quick hourly → salary
double the rate, read as thousands ($25/hr ≈
$50k; exact: ×2,080)
Overtime rate
1.5 × regular rate past 40 h/week (federal)
FICA (employee)
7.65% = Social Security 6.2% + Medicare 1.45%
Effective tax rate
total tax ÷ gross income — the rate that
predicts a paycheck
Lumber is named before drying and planing — the actual sizes are smaller:
Nominal
Actual
Nominal
Actual
1x6
0.75 × 5.5 in
2x4
1.5 × 3.5 in
2x6
1.5 × 5.5 in
2x8
1.5 × 7.25 in
2x10
1.5 × 9.25 in
2x12
1.5 × 11.25 in
4x4
3.5 × 3.5 in
6x6
5.5 × 5.5 in
Every figure here is explained, with its formula and a worked example, on the
matching calculator page — these are planning constants, and local code and product labels
override all of them.