Cu yd for 100 sq ft at 4 in?
About 1.23 cubic yards before buffer.
Concrete volume is **footprint area × depth**, converted to cubic yards for ready-mix orders or bags for small pours.
**Formula:**
Cu ft = sq ft × (depth in ÷ 12)
Cu yd = cu ft ÷ 27
Bags = ceil(cu ft ÷ yield per bag)
**Example — 10×10 ft slab, 4 in deep:**
100 × (4÷12) = 33.33 cu ft = **1.23 yd³**
≈ **75** sixty-pound bags (0.45 cu ft each)
Add **5–10% buffer** for uneven subgrade and spill.
Concise answers for common searches — definitions, steps, and comparisons.
About 1.23 cubic yards before buffer.
Rectangle, circle, or area footprint times depth, with optional order buffer.
Formula
cu_yd = (sq_ft × depth_ft) / 27; bags = ceil(cu_ft / bag_yield)Tap 10×10 patio, sidewalk, or post hole on the main form.
Rectangle L×W, total sq ft, or round pad diameter.
4 in for patios, 6–8 in for driveways and footings — use depth chips.
Results show cubic yards, bag counts by size, and ready-mix note.
Compact crushed stone under the slab — see Gravel Calculator.
Input
100 sq ft patioOutput
1.23 yd³ · 75×60 lb bags33.33 cu ft ÷ 27 = 1.23 yd³.
Input
240 sq ft drive padOutput
2.96 yd³80 cu ft — ready-mix territory.
Input
Round padOutput
≈ 1.4 yd³113 sq ft footprint × 4 in depth.
Common real-world scenarios where this tool saves time.
4 in slab ≈ 1.23 yd³ — bag mix or short-load ready-mix.
4 in × 80 sq ft ≈ 1 yd³ — common walk pour.
24 in deep — circle mode for fence posts.
Step-by-step chains that connect related tools for common tasks.
| Use | Depth |
|---|---|
| Patio / sidewalk | 4 in |
| Driveway | 6–8 in |
| Footings | 8 in+ |
| Bag size | Approx. yield |
|---|---|
| 40 lb | 0.30 cu ft |
| 60 lb | 0.45 cu ft |
| 80 lb | 0.60 cu ft |
Spill, over-dig, and uneven subgrade consume volume — enable the buffer.
Cold joints weaken slabs — schedule enough help for the calculated volume.
Compact gravel base **before** final depth measurement — subsidence changes volume.
Driveways need **6–8 in** depth — 4 in patio math will crack under vehicle load.
Under 1 yd³ ready-mix often costs more per yard — compare bag mix.
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At 4 inches thick: about 1.23 cubic yards or roughly 75 sixty-pound bags. Add 10% buffer for spill.
Divide total cu ft by bag yield (60 lb ≈ 0.45 cu ft) and round up. The calculator shows 40/60/80 lb counts.
Cu yd = (sq ft × depth in feet) ÷ 27. Example: 100 sq ft × 0.333 ft ÷ 27 = 1.23 yd³.
4 in for patios and walks. Driveways and garage slabs need 6–8 in — change depth on the form.
Under ~1 yd³, bag mix avoids short-load fees. Above 1 yd³, ready-mix delivery is usually cheaper per yard.
Gravel Calculator estimates compacted base under the slab. Concrete Calculator estimates the pour on top.
Use circle mode — enter diameter and depth for cu yd and bags.
Switch to metric — enter m² and depth in cm for m³ and liters.
5–10% buffer for uneven subgrade and spill — enable on the main form.
Use the post hole preset — 12 in diameter circle mode with your bury depth.
Dimensions stay on your device.
Estimates only — structural footings and PSI mix require engineered plans.
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Reviewed on 2026-06-27.
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What are you pouring?
Patios, sidewalks, driveways
Concrete depth presets
4 in for patios and walks, 6–8 in for driveways and footings. Measure after compacted base.
60 lb bag ≈ 0.45 cu ft yield. Leave blank to skip bag count.
1 cubic yard covers
| Depth | Sq ft |
|---|---|
| 1 in | 324 |
| 2 in | 162 |
| 3 in | 108 |
| 4 in | 81 |
Bag coverage at 4 in depth
| Bag | Covers | Per cu yd |
|---|---|---|
| 1 cu ft bag | 3 sq ft | 27 bags |
| 1.5 cu ft (40 L) | 5 sq ft | 18 bags |
| 2 cu ft bag | 6 sq ft | 14 bags |
| 3 cu ft bag | 9 sq ft | 9 bags |