How Much Concrete for a 16x16x48 Footing?
Materials and measurements for a 16" x 16" x 48" square footing: cubic feet, cubic yards, and bag counts
Quickly find how much concrete a 16" × 16" × 48" footing uses, the cubic feet and yards, plus how many 40-, 60-, or 80-lb bags you'll need with a standard 10% waste allowance.
A 16" × 16" × 48" square footing is a compact, deep footing that works for a single heavy post or a concentrated column where depth is important. Because this footing is 48" (4 ft) deep, it often appears in projects that need extra bearing depth or frost consideration.
Material-first planning helps here: a single footing contains 7.1111 cubic feet of concrete (0.2634 cubic yards), and when you include a 10% waste allowance plan for 7.8222 cu ft (0.2897 yd³). That makes bagged concrete a practical option for one or a few footings, while multiple footings may push you toward ready-mix.
Quick Answer
Exact volume: 7.1111 cubic feet (0.2634 cubic yards). With a 10% waste allowance plan for 7.8222 cubic feet (0.2897 cubic yards).
Bag planning (with 10% waste): 27 40-lb bags, 18 60-lb bags, or 14 80-lb bags. The exact bag counts without waste are 24 40-lb, 16 60-lb, or 12 80-lb.
Need a custom estimate? Use the Footing Calculator. Browse footing size pages. All project pages.
How to Use This Footing Estimate
Steps to prepare and pour a single 16" × 16" × 48" footing.
- Measure and mark the location, confirming the planned size is 16" × 16" and 48" deep.
- Excavate the hole to depth and check sides for stability; shore up if needed.
- Set forms or tamp the sides; ensure the footing is square and at the correct depth.
- Add reinforcement if required by design—typically rebar or a wire cage placed off the bottom and centered in the depth.
- Mix bagged concrete or arrange ready-mix delivery; pour until the form or excavation is filled to the specified level.
- Screed and finish the top, then protect and cure the concrete for several days per mix instructions.
Formula
The basic formula is area × depth = volume. Convert dimensions to feet first: length 1.3333 ft, width 1.3333 ft, depth 4 ft.
Area = 1.3333 ft × 1.3333 ft = 1.7778 square feet. Volume in cubic feet = area × depth = 1.7778 ft² × 4 ft = 7.1111 cubic feet.
To get cubic yards divide cubic feet by 27: 7.1111 cu ft ÷ 27 = 0.2634 cubic yards. Add your waste percentage (10% here) by multiplying by 1.10: 7.1111 cu ft × 1.10 = 7.8222 cu ft, or 0.2634 yd³ × 1.10 = 0.2897 yd³.
Worked Example
Single-post footing: one 16" × 16" × 48" footing requires 7.1111 cu ft of concrete, which is 0.2634 yd³. For ordering or buying bags, plan for 7.8222 cu ft (0.2897 yd³) which equates to 27 40-lb bags (or 18 60-lb, or 14 80-lb) including waste.
Three footings for a small porch: total volume = 3 × 7.1111 cu ft = 21.3333 cu ft, which converts to about 0.7902 cubic yards. With 10% waste plan for 3 × 7.8222 cu ft = 23.4666 cu ft (0.8691 yd³). Bag planning for three footings with waste would be 81 40-lb bags, 54 60-lb bags, or 42 80-lb bags, so compare that to ready-mix delivery options.
Bag Count Estimate
- 14 bags of 80 lb concrete mix
- 18 bags of 60 lb concrete mix
- 27 bags of 40 lb concrete mix
Always verify the actual yield on the product label before buying materials.
Bag Counts by Waste Buffer for 16" x 16" x 48"
Pick a buffer based on site conditions: clean forms and accurate measurements can run leaner; rough subgrade or hard-to-reach pours need more cushion.
| Buffer | Volume (ft³) | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|
| No buffer | 7.11 | 12 | 16 | 24 |
| +5% typical DIY | 7.47 | 13 | 17 | 25 |
| +10% recommended | 7.82 | 14 | 18 | 27 |
| +15% rough conditions | 8.18 | 14 | 19 | 28 |
When Bagged Concrete vs Ready-Mix Makes Sense
For a single 16" × 16" × 48" footing the planned volume with waste is only 0.2897 yd³, so buying bags of concrete mix is often the most convenient approach—you can purchase exactly the number of bags you need and mix on site. The planning bag counts are 27 40-lb, 18 60-lb, or 14 80-lb bags for one footing with 10% waste.
If you're pouring several footings, add the planning volumes. Three footings with waste come to about 0.8691 yd³; that approaches a yard of concrete and may make a ready-mix truck more efficient, especially when factoring labor, consistent slump, and faster placement. For small numbers of footings, bagged concrete gives flexibility; for larger counts or tight schedules, ready-mix can save time and ensure uniform quality.
Common Uses for This Footing Size
A 16x16x48 footing is commonly used for supporting deck posts, pergola posts, fence posts, and small porch columns. Its size fits well for single-point supports where the load isn’t very heavy. This footing can help keep posts stable in typical residential settings, especially for outdoor structures that don’t carry large amounts of weight.
Whether this footing size will work depends on several factors like how much weight the post needs to hold, the type of soil, how deep the frost line is in your area, and if reinforcement is necessary. Local building codes may also have specific requirements, so it’s important to consider these details before deciding on footing dimensions.
Common Mistakes to Avoid
Common pitfalls to avoid when planning and pouring this footing size.
- Underordering concrete by using exact volume and not adding at least 10% waste for spillage and over-excavation.
- Relying on the exact bag counts without accounting for on-site waste or partial bags.
- Skipping reinforcement or not following engineered rebar spacing when the load or soil requires it.
- Failing to verify local frost depth, bearing capacity, or permit requirements before digging.
- Pouring without proper form support or bracing; forms can bulge and change footing dimensions.
- Not planning curing time or protecting the pour from rapid drying, rain, or freezing temperatures.
Frequently Asked Questions
How much concrete volume does one 16" x 16" x 48" footing need?
One footing needs 7.1111 cubic feet of concrete, which is 0.2634 cubic yards. With a 10% waste allowance plan for 7.8222 cubic feet (0.2897 cubic yards).
How many bags of concrete mix should I buy for this footing?
With a 10% waste allowance, plan on 27 40-lb bags, 18 60-lb bags, or 14 80-lb bags for a single footing. The exact counts without waste are 24 40-lb, 16 60-lb, or 12 80-lb.
Why should I add 10% waste when ordering concrete?
A waste allowance covers minor over-excavation, spillage, uneven subgrade, and the extra needed to top off forms. For this footing 10% raises the volume from 7.1111 cu ft to 7.8222 cu ft.
Is this footing size suitable for a deck post?
It depends on the post load, soil bearing capacity, frost depth, and local code. This 16" × 16" × 48" footing provides 7.1111 cu ft of concrete, but you should confirm loads and have a structural review or follow building department guidance before relying on it for a deck post.
Keep Planning Your Concrete Project
Use the calculator, compare footing pages, and keep your estimate practical before you buy materials.
Disclaimer: This page provides planning estimates only. Actual concrete needs vary with excavation accuracy, site conditions, local code requirements, bag yield, and supplier guidance. Always verify measurements before buying materials, and consult a qualified professional for structural or code-sensitive work.