Concrete estimator
Circular Patio Concrete Calculator
Estimate concrete for circular patios using radius or diameter, depth, waste, bags, and cost ranges.
Country
Units
Dimensions
Enter the project measurements for this shape.
Measure the radius from the center to the edge, then measure depth at the finished slab or bed thickness.
Report Mode
Homeowner reports stay simple. Contractor reports include job details.
Materials
Buy what you need
Product suggestions are matched to this calculator material so you can compare package sizes and accessories before purchasing.
Concrete project supplies
Budget80 lb concrete mix bags
General-purpose bagged mix for slabs, patios, footings, and small repairs.
Search term: 80 lb concrete mix bag
Concrete project supplies
PremiumPortable concrete mixer
Rental-friendly mixer for larger bagged concrete pours.
Search term: portable concrete mixer
Add-ons
Common measuring and safety add-ons
Useful across measuring, setup, and cleanup.
Laser distance measure
Fast room and project measurements for length, width, height, and area.
Work gloves
General hand protection for mixing, cutting, carrying, and cleanup.
Safety glasses
Eye protection for mixing, cutting, sanding, and installation work.
How this circular patio calculator works
This calculator estimates concrete for a round patio, fire pit pad, circular landing, small equipment base, or garden feature from radius and depth. In imperial mode, enter radius in feet and depth in inches. In metric mode, enter radius in meters and depth in centimeters. The calculator converts radius to feet, calculates area with pi times radius squared, multiplies by slab depth, adds waste, and divides by the selected bag yield.
Radius is the distance from the center of the circle to the finished concrete edge. If you measured diameter instead, divide that measurement by two before entering it. For example, a 12 ft diameter patio has a 6 ft radius. At 4 inches deep, that circular slab is about 113 square feet before waste. With 10 percent waste and 80 lb bags that yield 0.6 cubic feet, the estimate rounds up to the nearest whole bag.
Circular forms can be harder to measure than rectangular forms because small radius errors affect the full area. Pull the tape from a marked center point to several locations on the form and use the largest intended finished radius if the edge is not perfectly round. When the patio includes a straight walkway, step, or square landing, estimate that piece separately with the rectangular calculator and add the quantities.
Bag yield reference table
| Package | Approximate yield | Notes for round patios |
|---|---|---|
| 40 lb concrete bag | 0.30 cu ft | Useful for edge corrections and small features |
| 50 lb concrete bag | 0.375 cu ft | Manageable weight for hand-mixed decorative pads |
| 60 lb concrete bag | 0.45 cu ft | Common choice where lifting 80 lb bags is impractical |
| 80 lb concrete bag | 0.60 cu ft | Efficient bagged option for many patio pours |
| Ready-mix concrete | 27 cu ft per cu yd | Often better for larger circular patios |
The table is a planning reference. Product labels control the final yield. Some bagged mixes are sold for high-strength, fast-setting, countertop, crack-resistant, or post-setting use and may not match the default yield or be appropriate for a patio slab. Check that the product is suitable for slab placement and finishing.
Common mistakes
The biggest circular-patio mistake is entering diameter as radius. That makes the estimate about four times too large because area depends on radius squared. The next mistake is using the planned seating diameter but forgetting the concrete border, edge form, or decorative band. Estimate the finished concrete, not just the furniture layout.
Round forms can also create waste. Flexible form boards, stakes, and curves may bow during placement. A low spot in the base near the edge can take more concrete than the neat geometry suggests. Keep the default waste unless the base is laser-flat and the form is very controlled. Increase waste when the radius is large, the edge is irregular, or the pour will be moved by wheelbarrow.
Regional pricing notes
Circular patios often involve more finish time than a simple rectangle because edging and joint layout require care. In regions with freeze-thaw cycles, contractors may recommend a compacted base, air-entrained concrete, drainage slope, and control joints that divide the round slab into manageable panels. In hot, dry regions, curing practice and shade can matter more because the surface can dry too quickly.
Bag prices should be local to the store and package size. Delivery minimums vary widely, so a project that looks small by cubic yards can still be expensive if ready-mix access is limited. For bagged jobs, include tool rental, mixer rental, and extra helpers in the budget if the bag count is high.
FAQ
Do I enter radius or diameter?
Enter radius. Radius is half the diameter. If your patio is 14 feet across, enter 7 feet as the radius.
Why is a small radius change so important?
Circle area uses radius squared. Increasing radius from 6 feet to 7 feet increases area from about 113 square feet to about 154 square feet, before depth and waste.
How much waste should I use for a circular patio?
Ten percent is a practical starting point. Use more if the form is flexible, the base is uneven, or the edge includes decorative curves and transitions.
Can I combine a round patio and walkway?
Yes. Estimate the round patio here, estimate the walkway as a rectangle, then add the bag counts and cubic yards together. Keep a little extra waste if both pours happen together.
Does the calculator include a gravel base?
No. It estimates concrete only. Base gravel, compaction, reinforcement, form materials, sealers, and tools should be budgeted separately.
When should I use ready-mix instead of bags?
When the bag count is too high for your crew to mix and place before the concrete stiffens, compare the cubic yards with ready-mix suppliers. Larger patios often favor delivery.
Sources and assumptions
Last updated 2026-05-03. The calculator uses the cited reference above, common retail package labels, and editable default assumptions for planning quantities. Confirm product coverage, package yield, price, and local requirements before purchasing materials or scheduling work.