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Outdoor living

A deck is rarely the whole project. It is a pergola over one corner, a paver path to the lawn, a fence along the property line, a privacy screen on the exposed side and lights on the posts. Each of those is a separate quantity problem with a different unit — pieces, square feet, linear feet, cubic yards.

Four units, four ways to be wrong

Project	Priced in	The mistake that costs most
Pergola	Pieces + linear feet	Forgetting overhang on every rafter, not just the ends
Pavers	Square feet + tons of base	Buying base at compacted depth — it compacts about 20%
Fence	Linear feet + post count	Counting posts by division instead of division plus one
Lighting	Fixtures + voltage drop	Running 60 W of 12 V LED through 100 ft of 18 AWG

Shade is a ratio, not a guess

The one pergola number most calculators omit is how much shade the rafters actually produce. It is simply the rafter face width divided by the on-centre spacing: 2″ rafters at 16″ centres block 12.5% of the plan area; 6″ rafters at 12″ centres block 50%. Everything between those two is a design decision, and it is arithmetic you can do before you buy.

The other half of the decision is orientation. Rafters running east–west shade the midday sun; north–south shade morning and afternoon and let noon through. Neither ratio changes, but which hours you spend in the shade does.

Pavers are a base problem wearing a surface costume

A paver patio is roughly 4″ of compacted aggregate, 1″ of bedding sand and 2⅜″ of paver — the paver is less than a third of the depth. Base is sold by the cubic yard or by the ton, and it is ordered loose to compact to the specified depth, so the quantity is larger than the finished volume by about a quarter. This is the single most common shortfall on a paver job, and it is arithmetic.

Low-voltage lighting is an electrical calculation

At 12 V, current is ten times higher than at 120 V for the same wattage, so resistance in the cable matters in a way it never does on a mains circuit. Voltage drop is 2 × length × current × resistance ÷ 1000, and it is why a run of 18 AWG cable that is fine at 40 ft is not fine at 120 ft. The calculator on this site computes the drop and flags the gauge, and it does not tell you how to wire a transformer.

Everything in this section

Pergola rafter calculatorRafter count, length with overhang, total linear feet and the shade percentage your spacing actually produces. Posts and beams counted, sizing left to the tables. Patio paver calculatorPaver count, loose base volume, sand and edge restraint for a patio. Base is ordered loose to compact, so the volume is larger than the finished depth. Fence post and picket calculatorPosts, rail linear feet, picket count and concrete per hole for a fence run. Enter length, spacing, height and picket width; get quantities, not guesses. Privacy screen calculatorBoards for a slatted privacy screen: count, linear feet, actual gap and the percentage of the screen that is closed, for horizontal or vertical slats. Deck lighting and voltage dropTotal load, current and voltage drop for 12 or 24 V deck lighting, with the maximum run per wire gauge and a gauge that reaches the last fixture. Stair handrail guideHandrail height, graspable profile dimensions, wall clearance and the 4-inch sphere rule applied to a sloped guard, with the IRC clauses that set each number. Deck inspection checklistA pre-inspection walk-through in the order an inspector does it: ledger and flashing, framing connections, footings, guard and stair dimensions, decay. Mulch calculatorHow much mulch a bed needs in cubic yards and bags, with depth guidance by bed type and the settlement allowance most estimates leave out. Topsoil calculatorTopsoil volume from area and depth, converted to cubic yards, tons and bags, with the compaction factor that makes delivered soil arrive short. Sod calculatorSod quantity from area, with roll and pallet counts, an allowance for cutting around edges, and the installation window that decides whether it survives. Retaining wall calculatorSegment blocks, caps and base gravel for a block retaining wall, with the height limit above which a wall needs an engineer rather than a calculator. Fire pit calculatorBlocks or bricks for a round fire pit, the inner diameter you actually get, and the clearance to combustibles that decides whether it is safe where you put it. Patio base calculatorCrushed aggregate and bedding sand for a paver patio, with loose-versus-compacted depths and the excavation volume that has to be removed first. Pergola shade calculatorHow much shade a pergola actually provides, from rafter width, spacing and sun angle. Includes why the noon number is not the number that matters. Gravel calculatorCubic yards and tons of gravel for a driveway, path or drainage bed, with density by aggregate type and the waste allowance to order with. Fence picket calculatorPicket, post and rail counts for a fence run, with the gap width that decides the picket count and the post spacing that decides everything else. Fence costInstalled fence cost per linear foot for wood, vinyl, aluminium and chain link, with the site factors that move a quote by 50% and the line items to check.

What this section does not do

Structural design of a pergola. Rafter sizing, beam sizing and post embedment are span-table questions like any other frame. The calculator counts and measures; it does not approve.
Electrical code. Low-voltage landscape wiring still has rules about burial depth, connections and transformers. The voltage-drop arithmetic is physics; the installation is code.
Fence law. Height limits, setback from the property line and which side faces the neighbour are local ordinances, not arithmetic.

Questions people actually ask

Which should I build first, the deck or the pergola?

The deck, always. Pergola posts either sit on the deck frame — which means blocking and a post base designed for it — or they bear on their own footings beside the deck. Both decisions depend on the deck layout, so the deck has to exist as a plan first.

Can pavers go directly on soil?

Not successfully. Without a compacted aggregate base and edge restraint, pavers settle unevenly, migrate outward and grow weeds within a season. The base is the structure; the paver is the wearing surface.

How deep do fence posts go?

Below frost depth in cold climates, and typically one third of the post's above-ground height as a rule of thumb elsewhere — a 6 ft post in a 2 ft hole. Local code or the fence manufacturer governs, and both should be checked before digging.

Do deck lights need an electrician?

Low-voltage (12 V) systems fed by a listed transformer are commonly a homeowner task, but the rules vary by jurisdiction and by whether the circuit is new. Anything touching 120 V — the transformer's supply — is electrician territory in most places.

Is a privacy screen the same as a fence?

No. A fence is a boundary structure and is usually regulated by height and setback. A screen attached to a deck or pergola is part of the structure, and a slatted screen behaves very differently in wind from a solid one — which matters for how it is fixed.

Deck material guideChoosing the surface material before the surrounds. Deck cost estimatorBudget the deck itself before adding structures. Deck code checklistGuard and stair dimensions that apply to the whole build.