SPECIFICATION: Front Entry Walkway, Side Yard Path, Garden Sidewalk

4×20 Concrete Sidewalk & Walkway Calculator

Q: How many bags of concrete for a 4x20 sidewalk at 3.5 inches?

You will need approximately 43 bags of 80 lb concrete (or 57 bags of 60 lb concrete) including 10% waste.

Q: How far apart should control joints be on a 4-foot wide sidewalk?

Control contraction joints should be spaced at intervals equal to the width of the walkway, so every 4 to 5 feet apart, cut to a depth of at least 1 inch.

A 4×20 sidewalk covers 80 square feet. At 3.5 inches thick (standard 2x4 screed depth), it requires 0.86 net cubic yards (0.95 cubic yards with 10% waste). Requiring 43 bags of 80 lb concrete, this is a very manageable 1-day DIY pour with two people.

SLAB DIMENSIONS80 SQ FT

LENGTH (FT)

WIDTH (FT)

THICKNESS (INCHES)3.5" Depth

Waste / Spillage Tolerance:+10%

Sub-Base Stone

Rebar Spacing

DIY Retail Bag Weight:

Live Structural Cross-Section

20' × 4' Slab (3.5" Depth)

Net Volume:0.86 cu yds

Order (+Waste):0.95 cu yds

Base Prep:2" Crushed Base

Reinforcement:Unreinforced

Yield Comparison (20' × 4')

DIY RETAIL STORE PICKUP

43 Bags

80 lb bags (~2 full pallets)

Dry Weight:3,440 lbs

Est. Bag Cost:$280

COMMERCIAL READY-MIX

0.95 cu yds

1 mixer truck (3500 PSI)

Delivery Scale:Short-Load Fee (<3 yds)

Est. Ready-Mix:$300

Frequently Asked Questions: 4×20 Concrete Sidewalk & Walkway Calculator

How many bags of concrete for a 4x20 sidewalk at 3.5 inches?

You will need approximately 43 bags of 80 lb concrete (or 57 bags of 60 lb concrete) including 10% waste.

How far apart should control joints be on a 4-foot wide sidewalk?

Control contraction joints should be spaced at intervals equal to the width of the walkway, so every 4 to 5 feet apart, cut to a depth of at least 1 inch.