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Concrete Patio Calculator

Calculate the ready-mix volume (cubic yards) or 60/80 lb bags required for backyard concrete patios. Automatically computes the necessary 1/4" per foot drainage pitch away from your home’s foundation to prevent water pooling.

Interactive Patio Calculator

ENGINEERING SCHEMATIC
Backyard Patio Slab with Slope
Length (L) Width (W) Thickness (T: 4"–6") Surface Area = L × W
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Pro Contractor Recommendation: Slope patio slabs away from the home foundation at 1/4 inch per foot (2%) for positive rainwater drainage.
Quick Presets:
Patio Dimensions & Shape
Concrete Volume Required
4.00 cu yds
(108.0 cu ft / 3.06 m³)
Patio Surface Area
300 sq ft
(27.9 m²)
Drainage Slope Fall
5.0 inches
1/4" per ft slope away from house
Subbase Crushed Stone
6.0 tons
Compacted 4-inch gravel base
Pre-Mixed Bags (80 lb)
180 bags
or 240 bags (60 lb)
Interactive 2D Blueprint

Rebar Grid & Control Joint Visualizer

Real-time scaled layout calibrated to ACI 318 structural concrete standards.

SCALE: DYNAMIC TO FIT ASPECT: 1:1 COVER: 3.0" PER ACI 318 JOINT DEPTH: T/4 = 1.0"
Slab Perimeter
Rebar Grid
Saw-Cut Control Joint
Tie Intersection
Slab Surface Area
100 sq ft
10.0' × 10.0' × 4"
Rebar Grid Counts
14 total bars
7 Long. • 7 Trans.
Total Rebar Linear Footage
146 linear ft
~98 lbs of #4 rebar (+10% lap)
Crack Control Joints
0 cuts needed
Max 10.0' spacing • 1.0" deep
Site Prep & Subgrade

Ground Excavation & Gravel Subbase

Concrete flatwork requires excavating native soil to accommodate both the compacted gravel base and slab thickness.

Concrete Slab Layer 4.0" Thickness
Compacted Crushed Stone Subbase 4.0" Base Depth
Geotextile Separation Fabric Underlayment
Undisturbed Native Soil Subgrade Tamped & Level
TOTAL DIG DEPTH
8.0"
(4" slab + 4" gravel)
Soil to Excavate & Haul
2.96 cu yds
~3.7 tons loose dirt • 1 dump truck load
Compacted Crushed Stone Base
2.1 tons
~1.5 cu yds (+15% mechanical compaction)
Geotextile Fabric Needed
110 sq ft
Prevents gravel sinking into native clay/subgrade
Ready-Mix Dispatch Helper

Call-a-Batch-Plant Order Cheat Sheet

Concrete dispatchers move fast. Have these exact technical answers ready when placing your ready-mix delivery call.

Copied to clipboard!
1. Volume to Request Rounded to 0.25 yd
1.50 cu yds

Includes +10% waste buffer. Plants meter in 1/4-yard increments.

Under 4.0 cu yds usually incurs a ~$75–$120 short-load fee.
2. Mix Design & Strength Structural Grade
3000 PSI

Standard residential flatwork mix for patios and walkways.

3. Slump & Aggregate Chute Pour
4" Slump • 3/4" Stone

Standard workability for direct chute pours. If using a line pump, specify 3/8" pea gravel mix.

4. Estimated Unload Time No Standby Fee
~30 Mins

Suppliers typically include 5–7 mins/yard free unloading. Additional truck standby costs ~$2.50–$3.50/minute.

Before the Truck Arrives — Site Readiness Checklist:
✓ 10' Clearance: Ensure 10-foot wide driveway and 14-foot overhead branch/wire clearance.
✓ Truck Weight: Fully loaded mixer weighs 60,000+ lbs. Never drive over septic tanks or soft ground.
✓ Washout Station: Prepare a designated dirt hole or tarped bin for driver chute washout.
✓ Crew Ready: Have wheelbarrows, screeds, bull floats, and crew on site 15 mins before scheduled pour.
Contractor Bid & Material Takeoff Sheet

Export or print an executive 1-page PDF job estimate with material checklist.

CONCRETECALCPRO STRUCTURAL ESTIMATION & JOB TAKEOFF
Document: Project Material Takeoff
Date:
Type: Concrete Patio Project

1. Project Dimensions & Area Specifications

Length Width Thickness Surface Area

2. Concrete Volume & Batch Order Requirements

Net Calculated Volume Recommended Order (+10% Waste) 80-lb Pre-Mix Bags 60-lb Pre-Mix Bags

3. Steel Reinforcement & Crack-Control Joint Schedule

Rebar Specification Grid Spacing Bar Count Linear Footage Total Steel Weight Control Saw Cuts

4. Jobsite Material Checklist

Ready-Mix Concrete Truck or Pre-mixed Bags
Deformed Steel Rebar / Welded Wire Mesh
Concrete Dobie Chairs (to suspend rebar at 2" depth)
16-Gauge Tie Wire & Rebar Safety Caps
Formwork Lumber (2×4 or 2×6) & Wooden/Steel Stakes
6-mil or 10-mil Polyethylene Vapor Barrier
1/2" Expansion Joint Filler Strips (at walls/slabs)
Compacted Crushed Stone Subbase (2.1 tons • 4" depth)
Soil Excavation & Hauling (3.0 cu yds loose dirt)
Project / Jobsite Address:
Contractor / Estimator Name:
Client Approval Signature:
Target Pour Date:

Engineering Disclaimer: This takeoff sheet provides estimation guidelines in accordance with ACI 318 & 360R standard residential flatwork practices. Subgrade deflection, form expansion, ground slope, and contractor placing practices will affect final concrete volume. Always confirm structural requirements with local building authorities and structural plans prior to placing orders.

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Why Drainage Slope Matters for Patios

A flat patio will trap rain and melted snow against your home's foundation wall, causing basement water leaks and freeze-thaw surface spalling. Concrete flatwork guidelines specify a minimum slope of 1/4 inch per linear foot (approx. 2% grade) away from the house structure.