How Much Concrete for a 16x24x48 Footing?
Concrete for a 16" x 24" x 48" footing — cubic feet, cubic yards, and bag estimates with waste.
Exact volume and planning totals for a 16" x 24" x 48" rectangular footing. Includes cubic feet, cubic yards, and bag counts adjusted for 10% waste for 40-, 60-, and 80-lb bags.
This 16" x 24" x 48" rectangular footing is sized to support things like a deck or pergola post where a deeper footing helps resist frost and lateral forces. It’s a practical option when you need a stout point bearing below grade for a single post or light structure.
Before you pour, check site-specific requirements: soil bearing capacity, frost depth, permits, and reinforcement expectations from your local building department. Those conditions determine whether this depth and width are appropriate or if a structural design is required.
Quick Answer
The footing holds 10.6667 cubic feet of concrete, which is 0.3951 cubic yards per footing. For planning, include 10% waste, giving 11.7334 cubic feet or 0.4346 cubic yards.
Bagged concrete planning counts (with 10% waste) are: 40 of the 40-lb bags, 27 of the 60-lb bags, or 20 of the 80-lb bags. Exact bag counts before waste are 36 (40-lb), 24 (60-lb), and 18 (80-lb).
Need a custom estimate? Use the Footing Calculator. Browse footing size pages. All project pages.
How to Use This Footing Estimate
Quick steps to go from measurement to pour for a single 16" x 24" x 48" footing:
- Confirm footing location and any required setbacks or depths with your local building department.
- Excavate to the 48" depth and size the hole to 16" × 24", keeping sides fairly vertical.
- Compact the bottom, place any required gravel base, and set reinforcement per plan.
- Mix or stage bagged concrete or schedule ready-mix to the planned volume.
- Place concrete, consolidate to remove voids, and finish the top; keep it moist for proper curing.
- Protect the fresh concrete from rapid drying and follow cure times before loading.
Formula
Calculate footing volume by multiplying length × width × depth in feet. Use the provided decimal-foot dimensions: 1.3333 ft × 2 ft × 4 ft.
Applying the numbers: 1.3333 × 2 × 4 = 10.6667 cubic feet of concrete required for one footing. To convert to cubic yards, divide cubic feet by 27.
So 10.6667 ÷ 27 = 0.3951 cubic yards. To plan for waste and small variations, multiply by 1.10 (10%): 10.6667 × 1.10 = 11.7334 cubic feet (0.4346 cubic yards).
Worked Example
Single-footing example: one 16" × 24" × 48" footing needs 10.6667 cubic feet (0.3951 cubic yards). With 10% waste plan for 11.7334 cubic feet (0.4346 cubic yards), equal to about 40 40-lb bags or 27 60-lb bags or 20 80-lb bags.
Multiple-footing example: three identical footings for three pergola posts equal 3 × 10.6667 = 32.0001 cubic feet. Convert that total: 32.0001 ÷ 27 = 1.1852 cubic yards. If you include 10% waste, plan for 3 × 11.7334 = 35.2002 cubic feet (about 1.3037 cubic yards) and roughly 120 40-lb bags total.
Bag Count Estimate
- 20 bags of 80 lb concrete mix
- 27 bags of 60 lb concrete mix
- 40 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 24" 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 | 10.67 | 18 | 24 | 36 |
| +5% typical DIY | 11.2 | 19 | 25 | 38 |
| +10% recommended | 11.73 | 20 | 27 | 40 |
| +15% rough conditions | 12.27 | 21 | 28 | 41 |
When Bagged Concrete vs Ready-Mix Makes Sense
For a single 16" × 24" × 48" footing the total planned volume with waste is only 0.4346 cubic yards. Bagged concrete is often the most practical choice because it lets you buy exactly what you need in manageable packages and avoid minimum truck orders.
Ready-mix offers faster placement and consistent mix quality, but suppliers commonly set minimums near 1 cubic yard or charge for small loads—so for this footing a short ready-mix delivery may cost more than bagged mix. If you have several footings or other concrete needs on the same day, ready-mix can become economical.
Common Uses for This Footing Size
A 16x24x48 footing is commonly used for supporting posts in residential projects. You might see it under deck posts, pergola supports, fence posts, or small porch columns. Its rectangular shape and size help spread the load over a decent area, which can be useful for these kinds of single-point supports. This footing size fits well when you need something a bit larger than a typical post base but don’t want to go too big for light structures.
Keep in mind that whether this footing size is right depends on several factors. The weight it needs to hold, the type of soil, how deep frost lines go in your area, and if any reinforcement is necessary all play a role. Local building codes also influence what footing dimensions are acceptable for your project.
Common Mistakes to Avoid
Watch out for these common pitfalls when planning and pouring a 16" × 24" × 48" footing:
- Underordering concrete by forgetting waste or slight over-excavation.
- Not checking local depth and permit requirements before digging.
- Failing to compact the footing bottom or provide a small gravel leveling pad.
- Omitting required reinforcement or misplacing rebar per the plan.
- Poor mixing consistency when using bagged concrete or not following bag instructions.
- Neglecting proper curing, which reduces long-term strength.
Frequently Asked Questions
How much concrete do I need for a 16x24x48 footing?
One 16" × 24" × 48" footing requires 10.6667 cubic feet of concrete, which equals 0.3951 cubic yards. With 10% waste included, plan for 11.7334 cubic feet (0.4346 cubic yards).
How many bags of concrete mix should I buy for this footing?
Exact bag counts (no waste) are 36 of the 40-lb bags, 24 of the 60-lb bags, or 18 of the 80-lb bags. With 10% planning allowance, buy about 40 40-lb bags, 27 60-lb bags, or 20 80-lb bags.
How much extra should I add for waste when ordering concrete?
A 10% allowance for waste is standard for small footings and was used here. That increases the volume from 10.6667 cu ft to 11.7334 cu ft (0.3951 yd3 to 0.4346 yd3) per footing to cover spillage and slight over-excavation.
Is a 16x24x48 footing big enough for a deck post?
It depends on the post load, soil bearing capacity, frost depth, and local building code. A 48" depth may be suitable where that aligns with local frost-depth requirements, but check with your local building department or a structural engineer for a final determination.
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.