Construction Calculators

Cubic yards of concrete for a rectangular slab/footing OR a cylindrical column/sonotube — with waste factor.

Translate cubic feet of concrete into the number of pre-mix bags you need at 40, 60, or 80 lb per bag.

How many bags of mortar are needed for a given brick or block count? Uses standard mortar-per-brick consumption.

How many bricks do you need for a wall? Enter dimensions, brick size, and joint thickness.

Linear feet of rebar needed for a slab grid, given dimensions and on-center spacing.

Cubic yards and tons of gravel for a driveway, base course, or landscape area.

Cubic yards and tons of sand for a base, paver bed, or sandbox.

How many cubic yards or 2-cubic-foot bags of mulch do you need for a flowerbed or landscape area?

Cubic yards and 40-lb bags of topsoil for a lawn renovation, garden bed, or fill area.

Tons of hot-mix asphalt for a driveway or parking area, given dimensions and lift thickness.

How much water to add to a bag of cement for a target water-cement ratio (and matching aggregate volumes for a 1:2:3 mix).

How many cubic yards or tons of crushed stone for a driveway base, French drain, or landscape.

Gallons needed — enter the wall area directly OR room dimensions (calculator subtracts doors/windows).

Exterior coverage typically 250-300 ft²/gal — rougher surfaces, porous siding.

Sheets needed = wall area / sheet area (32 ft² for 4×8, 48 ft² for 4×12).

Board-feet = (thickness in × width in × length ft) / 12 × pieces.

Total = pieces × length × $/LF.

Studs needed = wall length / spacing + corners + 10% waste.

1 roofing square = 100 ft². Bundles = squares × 3 (for 3-tab) or × 4 (architectural).

Bundles = roof area / coverage per bundle (33⅓ ft² for 3-tab).

Sheets = surface area / 32 ft² (standard 4×8 sheet) + waste.

Tiles = ceiling area / tile area, plus grid-feet for the suspended grid.

Posts, panels, and rails for a wood/vinyl/chain-link fence.

Decking boards, joists, posts, and fasteners for a residential deck.

Boxes/units of flooring needed = room area / box coverage + waste.

Length × width = ft². The simplest area calc.

Two-rectangle L-shaped area = (L1×W1) + (L2×W2).

Sum of rectangles. Enter length×width pairs (one per line).

Perimeter × ceiling height − doors and windows = paintable area.

Ceiling area = floor area (for flat ceilings).

L × W = floor area in ft². For flooring orders, multiply by 1.10 (10% waste).

L × W × H = ft³. Used for air-change calculations and AC/heating sizing.

Effective attic floor area accounting for sloped roof. Useful for insulation orders.

L × W = deck area. For decking material order, see deck-material.

L × W = patio area. For paver/concrete orders.

L × W = driveway area. For asphalt, concrete, or gravel orders.

L × W = lawn area. For seed, sod, fertilizer orders.

Pool gallons = L × W × avg-depth × 7.48.

Same template as pool: L × W × avg-depth × 7.48 gallons. For garden ponds.

L × W × D = ft³ of soil needed for a raised bed or planter box.

BTU/hr needed = ft² × climate factor (20-30 BTU/ft² for typical US climates).

Heating BTU/hr = ft² × insulation factor × ΔT.

1 ton = 12,000 BTU/hr cooling. Convert sqft → tons (rule-of-thumb sizing) OR BTU → tons (direct).

Furnace BTU = ft² × climate-zone factor (30-60 BTU/ft²).

CFM (cubic feet per minute) = BTU/hr × 0.07. Used for sizing ducts.

Heat loss = U × area × ΔT for each surface, summed.

Pints/day needed based on room ft² and humidity level.

V = IR. Pick which to solve for. Residential circuit framing.

NEC ampacity: typical residential AWG sizes for current load.

Vd = (2 × K × I × L) / CM for single-phase circuits. NEC recommends ≤ 3% drop.

ROI = (post-value − pre-value − reno cost) / reno cost. Factor in regional appreciation to separate true ROI from market gains.

Kitchen remodel cost = sq ft × $/ft² (basic / mid-range / luxury) + appliance package.

Bathroom remodel cost = sq ft × $/ft² (basic / mid / luxury) + fixture package.

Deck cost = sq ft × material rate. Pressure-treated, cedar, composite, and hardwood pricing built in.

Fence cost = linear feet × $/LF. Wood, vinyl, chain-link, aluminum rates.

Painting cost = (wall + ceiling) ft² × $/ft² labor & materials. Interior or exterior.

HVAC replacement cost = base price by tonnage × system type multiplier (AC, heat pump, furnace+AC).

Roof replacement = squares × $/square (asphalt / metal / tile) + tear-off & disposal.

Flooring cost = sq ft × $/ft² (hardwood / tile / vinyl / carpet) + removal of existing.

Invoice = (material + labor) × (1 + markup %). Standard residential markup is 15-25%; remodeling 20-30%.

Home equity line of credit payment — interest-only during draw, amortizing during repayment.

Construction loan: interest-only on disbursed balance during build, then converts to permanent mortgage.

Side-by-side: secured renovation loan (lower rate, longer term) vs. unsecured personal loan (higher rate, shorter term).

Distribute total contract across milestones (deposit / start / mid / completion) by % allocation.

Monthly cash flow = inflows (loan draws, owner contributions) − outflows (labor, materials) over project duration.

Revised total = base contract + change orders + contingency. Track scope creep against budget.

Holdback = total contract × holdback % (typically 10%). Released after lien period and punch list complete.

Safe budget = base × (1 + contingency %). New construction 5%, remodels 10-15%, gut renos 20%+.

Rental cost = best of (daily × days) vs. (weekly × weeks) vs. (monthly × months) — picks the cheapest tier.

Days = remaining budget / daily burn rate. Works backward from spend to project schedule.

Required breaker amps = load watts × 1.25 / volts. NEC 80% derate rule.

Cost = W × hr/day × 30 / 1000 × $/kWh.

Panels = daily kWh need / (panel-W × sun-hours × derate / 1000).

NEC 40% fill (3+ wires). Find conduit size that holds N wires of given gauge.

PSI = ft of head × 0.433. Or 1 PSI = 2.31 ft of water column.

D = 2 × √(GPM / (velocity × π × 144 × 7.481 / 60)). Find pipe size to deliver target GPM.

Slope (in per ft) × run length = total drop. Standard ¼" per ft.

IPC table: 750-1500 gal by bedroom count. State codes vary.

GPH = (BTU/hr × efficiency) / (8.33 × ΔT). Hot water output rate.

HP = (GPM × ft head) / (3960 × pump efficiency).

Add up areas from up to 4 rectangles, triangles, and circles, then size the flooring order with waste + cost.

Convert between rise/run (X/12), degrees, and % slope — all three representations of the same roof angle.

Tiles needed = (room area / tile area) × pattern-waste factor. Auto-rounds to whole tiles + box count.

Standard double-roll coverage = 56 ft² (random match) / 50 ft² (straight match) / 38 ft² (drop match). Subtracts doors + windows.

From total rise + tread depth, compute riser count, individual rise, stringer length (Pythagorean), and IRC compliance check.

Estimate the cooling BTU/h needed for a room from its area, occupancy, sun exposure, insulation, and climate, following ENERGY STAR sizing guidance.

Size a storage water heater by peak-hour hot-water demand (First Hour Rating) or size a tankless unit by peak simultaneous flow, using DOE worksheet values.

Wall area + scratch/brown/finish coat thickness → bags of stucco mix needed (3-coat system).

Number of drywall sheets → joint-compound buckets and feet of tape for taping/finishing.

Tile area + tile size + joint width + tile thickness → grout pounds needed.

Room area + padding type → padding rolls and total weight needed.

Room area + plank dimensions → plank count, boxes, and waste-adjusted purchase quantity.

Room area + plank or sheet size → plank/sheet count, boxes, and waste-inflated purchase quantity.

House perimeter + roof overhang → linear feet of fascia and ft² of soffit material needed.

US DOE climate zone + location (attic / wall / floor) → recommended R-value with cost-benefit context.

Deck size + board width + gap + joist spacing → deck boards, joists, beams, and screws/fasteners.

Roof area + shingle type → bundles, nails, and starter strip with 10% waste built in.

Water + cement weights → w/c ratio and estimated 28-day compressive strength (Abrams' law).

Mortar volume + ASTM C270 type → Portland cement, hydrated lime, and sand quantities by proportion.