Pavers and patio base calculator

How to estimate pavers and a patio base in five steps

1. Type the size of the area. Choose a rectangle, a circle or a triangle with three sides, in feet or in meters. If you have several matching areas, such as two pads, type that number and the calculator multiplies for you.
2. Pick the paver and the joint. Choose a common face size or type your own. Type the joint width from your paver's installation guide, then pick the laying pattern. The pattern fills in a waste percentage you can change.
3. Read the number of pavers. You get the area, the area with waste and the number of pavers, rounded up. If you type the coverage of a pallet from the maker's label, you also get the number of pallets.
4. Add the base, the sand and the edging if you want them. Type a depth for the gravel base and for the bedding sand, a joint sand rate and bag weight from the bag label, and a spike spacing. Each box you leave empty is skipped. You get cubic yards, tons as a low to high range, bags and spikes.
5. Add your own prices if you like. Type a price for each material and a low to high range appears. Compare up to a few bids per square foot, then print a bilingual sheet to bring to your supplier or contractor.

What this calculator does, and what it does not

This page turns the size of an area and the size of a paver into quantities: how many pavers, how many pallets, how much gravel and sand for the layers underneath, how much joint sand and how long the edge restraint is. It handles a rectangle, a circle and a triangle, in feet and inches or in meters.

It is an estimate, not a quote and not a plan. It does not know your soil, your slope, how water moves across your yard or how the paving will be used. It gives no advice on how deep a base should be, what kind of gravel or sand to use, how to edge the paving or whether a permit is needed. Your paver's installation guide, your supplier, your building department and your contractor answer those questions.

How the area is worked out

A rectangle is length times width. A circle is pi times the radius squared, where the radius is half the diameter you type. A triangle is worked out from its three sides, and the calculator tells you if the three sides cannot make a triangle. Metric lengths are converted with the standard definitions, so one foot is 0.3048 meters and one inch is 2.54 centimeters.

How the number of pavers is worked out

Pavers are laid with a small joint between them, so each paver uses up a little more than its own face. The calculator adds the joint width to the length and to the width, then multiplies them. A 6 by 9 inch paver with a one eighth inch joint takes up 6.125 by 9.125 inches, which is 55.8906 square inches.

It then divides the area, with waste added, by that figure and rounds up to a whole paver. If you type the coverage of a pallet from the maker's label, it divides the same area by that to show pallets. Rounding is done after trimming the tiny errors a computer leaves in long decimals, so a job that comes out to a whole 300 pavers shows 300 and not 301.

A worked example: a 12 by 10 foot patio

Say a patio is 12 feet by 10 feet, which is 120 square feet. The pavers are 6 by 9 inches with a one eighth inch joint, laid in a straight pattern with 5 percent waste. The area with waste is 126 square feet, which is 18,144 square inches. Divide by 55.8906 and you get 324.63, so the calculator shows 325 pavers.

Now add the layers underneath. Type a base gravel depth of 4 inches and the volume is 120 times 4 divided by 12, which is 40 cubic feet or 1.4815 cubic yards. With the 20 percent compaction extra, that becomes 1.7778 cubic yards to order, and at 1.4, 1.55 and 1.7 tons per cubic yard it is about 2.49, 2.76 and 3.02 tons. Bedding sand at 1 inch is 0.3704 cubic yards, or about 0.48, 0.52 and 0.56 tons.

If a bag label says 80 pounds of joint sand for every 100 square feet, the 120 square feet take 96 pounds, which is 2 bags of 50 pounds. The edge is 2 times 12 plus 10, which is 44 linear feet, and with a spike every 12 inches that is 44 spikes. The depths and the label rate in this example are only numbers to show the arithmetic.

Why waste is added, and how the pattern changes it

Cut pavers and chipped ones mean you order more than the area calls for. The calculator starts with 5 percent for a straight or running bond layout, 15 percent for a 45-degree herringbone or a diagonal layout, and 20 percent for curves or a complex shape. These are typical assumptions, not a maker's figures, so they are labeled that way and you can type your own number. Ask your supplier what they suggest for your layout and your cutting.

Base gravel and bedding sand

Under the pavers there is usually a layer of compacted gravel and a thin layer of sand to set them in. This page only does the arithmetic for the depths you type: area times depth gives the volume, and 27 cubic feet make one cubic yard.

Loose gravel settles when it is compacted, so you order more than the finished volume. The compaction extra box starts at 20 percent as a typical assumption and you can change it. The sand layer is leveled rather than packed, so it gets no extra.

Suppliers often sell by the ton, and a cubic yard of loose material weighs a range. The calculator shows tons as a low, a middle and a high figure, using 1.4 to 1.7 tons per cubic yard for gravel and crushed stone and 1.3 to 1.5 for dry sand. Those weights come from calculator tables, not from a maker, and wet material weighs more, so ask your supplier.

As an example only, one maker's installation guide shows 4 to 6 inches of compacted gravel under its pavers for pedestrian areas, and many guides show about 1 inch of bedding sand. Those are examples of what is printed, not a recommendation for your site. Your paver's guide and your supplier decide your depths.

Joint sand and edge restraint

Joint sand is swept into the joints after the pavers are down. Bags of it print a rate, such as pounds per 100 square feet at a given joint width. Type the rate and the weight of one bag and the calculator multiplies, divides and rounds up to whole bags. There is no built-in rate, because it depends on your product and your joint.

Edge restraint is a strip or border that holds the outer pavers in place, fixed with spikes. The calculator gives its length from the edge of your shape. If you type a spike spacing from the restraint's instructions, it counts the spikes too. Where the restraint is needed and how it is fixed are questions for the product's instructions.

How to read a contractor's quote

Compare quotes for the same work. A low number can leave out things another quote includes. The bid comparison on this page shows each bid per square foot so a small patio and a large one can be compared on the same footing. Use the questions below as a starting point.

• How many square feet does the quote cover, and how was the area measured?
• What base material and depth are included, and how is it compacted?
• Is edge restraint included, and is joint sand included?
• Who arranges the permit, if one is needed, and what is in writing about the work?

What an estimate cannot know

A calculator works only from the numbers you type, and cannot see soft ground, roots or a slope. Before you dig, call 811. It is the free number for having buried utility lines marked, and it is a pointer only. For depths, materials, edging and permits, ask your building department, your supplier and your contractor. This page does not decide any of them.

Metric units

Switch to metric and type meters for the area, centimeters for the paver and the depths, and millimeters for the joint. The ready-made sizes in the list are in inches because that is how they are sold, so use the custom size if you have centimeters. As an example, a 4 by 3 meter area is 12 square meters. With paving stones of 20 by 10 centimeters, a 3 millimeter joint and 5 percent waste, the calculator shows 603 pavers.

Frequently asked questions