py-concrete-calc

Concrete volume, bag, material, and cost calculations for construction projects.

A Python library for estimating concrete quantities — from simple slab volumes to full project takeoffs with rebar, wire mesh, formwork, and regional pricing. Built by SlabCalc.co, the free online concrete calculator.

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Installation

pip install py-concrete-calc

For pandas DataFrame support:

pip install py-concrete-calc[pandas]

Quick Start

from concrete_calc import estimate, inches_to_feet

# 20 ft × 10 ft slab, 4 inches thick
result = estimate(length=20, width=10, thickness=inches_to_feet(4))

print(f"Volume: {result.cubic_yards} cubic yards")
print(f"80 lb bags needed: {result.bags}")
print(f"Ready-mix cost: ${result.ready_mix_cost_total}")
print(f"Bag cost: ${result.bag_cost_total}")

Full project estimate with materials

from concrete_calc import estimate, inches_to_feet

result = estimate(
    length=20,
    width=10,
    thickness=inches_to_feet(4),
    waste_factor=1.10,       # 10% extra for waste
    include_materials=True,  # adds rebar, wire mesh, forms
    rebar_spacing_in=12,     # 12" on-center
    rebar_bar_size=4,        # #4 rebar
)

print(f"Concrete: {result.cubic_yards} yd³")
print(f"Rebar: {result.rebar['pieces_20ft']} pieces (20 ft bars)")
print(f"Wire mesh: {result.wire_mesh['sheets_5x10']} sheets")
print(f"Form boards: {result.forms['boards_8ft']} boards (8 ft)")

Using the ConcreteCalculator class

from concrete_calc import ConcreteCalculator

calc = ConcreteCalculator()

# Volumes for different shapes
print(calc.slab(20, 10, 0.333))          # rectangular slab
print(calc.cylinder(diameter=2, height=4)) # sonotube column
print(calc.footing(30, 1.5, 1))           # continuous footing
print(calc.stairs(0.75, 1.0, 3.0, 5))     # 5-step staircase
print(calc.wall(20, 8, 0.5))              # concrete wall
print(calc.circular_slab(10, 0.333))       # round pad

Shape Calculators

All shape functions accept dimensions in consistent units (feet or meters) and return volume in cubic units.

Function	Description	Online Calculator
slab(l, w, t)	Rectangular slab	Slab Calculator
cylinder(d, h)	Round column / sonotube	Column Calculator
footing(l, w, d)	Continuous footing	Footing Calculator
stairs(rise, run, w, n)	Staircase	Stairs Calculator
curb(l, w, h)	Curb / barrier	Curb Calculator
wall(l, h, t)	Concrete wall	Wall Calculator
hollow_cylinder(od, id, h)	Hollow column	—
circular_slab(d, t)	Round pad / fire pit	—
triangular_prism(b, h, l)	Ramp / tapered edge	—
grade_beam(l, w, d, n)	Grade beam	—

Bag Estimation

from concrete_calc import bag_estimate, bags_from_yards

bags = bag_estimate(cubic_feet=27, bag_size=80)  # 45 bags
bags = bags_from_yards(cubic_yards=1, bag_size=60)  # 60 bags

Supports 40, 50, 60, and 80 lb bags. For a visual breakdown, see How Many Bags of Concrete Do I Need?

Cost Estimation

from concrete_calc import ready_mix_cost, bag_cost

# Ready-mix truck delivery
r = ready_mix_cost(cubic_yards=5, price_per_yard=160)
print(f"${r['cost']}")  # $800.00

# Bagged concrete from the hardware store
b = bag_cost(cubic_feet=27, bag_size=80, price_per_bag=6.50)
print(f"{b['bags']} bags = ${b['cost']}")  # 45 bags = $292.50

For current pricing in your area, check the Concrete Cost Calculator.

Regional Pricing Database

from concrete_calc import get_regional_price, list_regions

print(list_regions())
# ['midwest', 'national', 'northeast', 'southeast', 'southwest', 'west']

ne = get_regional_price("northeast")
print(f"Northeast: ${ne['price_per_yard']}/yd³")  # $175.00/yd³

Material Quantities

from concrete_calc import rebar_estimate, wire_mesh_estimate, form_lumber_estimate

# Rebar grid for a 20×10 ft slab
rebar = rebar_estimate(20, 10, spacing_in=12, bar_size=4)
print(f"{rebar['pieces_20ft']} bars, {rebar['weight_lbs']} lbs")

# Welded wire mesh
mesh = wire_mesh_estimate(20, 10)
print(f"{mesh['sheets_5x10']} sheets (5×10 ft)")

# Perimeter forms
forms = form_lumber_estimate(20, 10)
print(f"{forms['boards_8ft']} boards, {forms['stakes']} stakes")

Unit Conversions

from concrete_calc import (
    cubic_feet_to_yards,
    cubic_yards_to_cubic_feet,
    cubic_feet_to_meters,
    cubic_meters_to_yards,
    inches_to_feet,
    cm_to_meters,
)

cubic_feet_to_yards(27)       # 1.0
inches_to_feet(4)             # 0.333...
cm_to_meters(10)              # 0.1

Export Results

from concrete_calc import estimate, inches_to_feet, to_json, to_csv

r = estimate(20, 10, inches_to_feet(4))

# JSON
print(to_json(r))

# CSV (multiple estimates)
projects = [
    estimate(20, 10, inches_to_feet(4)),
    estimate(30, 12, inches_to_feet(6)),
]
print(to_csv(projects))

Pandas Integration

from concrete_calc import estimate, inches_to_feet
from concrete_calc.export import to_dataframe

projects = [
    estimate(20, 10, inches_to_feet(4)),
    estimate(30, 12, inches_to_feet(6)),
    estimate(15, 15, inches_to_feet(4)),
]

df = to_dataframe(projects)
print(df[["cubic_yards", "bags", "ready_mix_cost_total"]])

Jupyter Notebook Example

# Cell 1: Install
# !pip install py-concrete-calc

# Cell 2: Quick slab estimate
from concrete_calc import ConcreteCalculator, inches_to_feet

calc = ConcreteCalculator()

# Garage slab: 24 ft × 24 ft × 4 in
thickness = inches_to_feet(4)
result = calc.estimate(24, 24, thickness, include_materials=True)

print("=== Garage Slab Estimate ===")
print(f"Concrete: {result.cubic_yards} cubic yards")
print(f"80 lb bags: {result.bags}")
print(f"Ready-mix cost: ${result.ready_mix_cost_total:,.2f}")
print(f"Bag cost: ${result.bag_cost_total:,.2f}")
print(f"Rebar (20ft bars): {result.rebar['pieces_20ft']}")
print(f"Wire mesh sheets: {result.wire_mesh['sheets_5x10']}")
print(f"Form boards (8ft): {result.forms['boards_8ft']}")

# Cell 3: Compare multiple projects
from concrete_calc.export import to_dataframe

projects = [
    calc.estimate(10, 10, inches_to_feet(4), include_materials=True),
    calc.estimate(20, 10, inches_to_feet(4), include_materials=True),
    calc.estimate(24, 24, inches_to_feet(4), include_materials=True),
    calc.estimate(30, 30, inches_to_feet(6), include_materials=True),
]

df = to_dataframe(projects)
df.index = ["Small patio", "Walkway", "Garage", "Large slab"]
print(df[["cubic_yards", "bags", "bag_cost_total", "ready_mix_cost_total"]])

Common Projects Reference

Project	Typical Size	Calculator
Sidewalk	4 ft × 20 ft × 4 in	Slab Calculator
Patio	12 ft × 12 ft × 4 in	Slab Calculator
Garage floor	24 ft × 24 ft × 4 in	Slab Calculator
Driveway	10 ft × 20 ft × 5 in	Slab Calculator
Deck footing	12 in dia × 48 in deep	Column Calculator
Fence post	8 in dia × 24 in deep	Column Calculator
House footing	20 ft × 18 in × 12 in	Footing Calculator
Retaining wall	20 ft × 4 ft × 8 in	Wall Calculator

API Reference

Full API documentation is available inline via docstrings. Use help(function_name) in Python or your IDE's autocomplete.

For interactive calculators with visual breakdowns, visit SlabCalc.co.

License

MIT — Built by SlabCalc.co