How to use the gravel calculator
This online gravel calculator works out how much gravel you need from three things: the area, the depth and the type of stone. It gives the answer in tons (or tonnes), cubic yards (or m³) and bags, so you can order by weight, by volume or off the shelf.
Leave Add 10% for compaction and waste ticked for driveways and bases that you will compact. Bags are always rounded up to whole bags.
How do I choose gravel?
Gravel covers everything from smooth pea stones to angular crushed rock. The shape decides how well it stays put.
Crushed gravel
Angular pieces that lock together under tyres and feet.
Best for driveways
Pea gravel
Small and round. Comfortable to walk on but moves around.
Best for paths and patios
Road base
Crushed stone with fine dust that packs down hard.
Best as a base layer
Decorative gravel
Coloured or polished stone for show.
Best for borders and beds
Gravel sizes and local names
Suppliers sell the same few kinds of stone under many names and sizes. Use this guide to pick the closest Material setting in the calculator.
For smooth, rounded stone see the River rock calculator, and for larger decorative stone the Landscape rock calculator.
Planning the rest of the job? Use the Pea gravel calculator and the Stone calculator too.
How deep should gravel be?
These are compacted depths. Lay thick layers in stages of 3 to 4 in (7.5 to 10 cm) and compact each one before adding the next.
Working out the depth from what you have
If you already have gravel, turn the formula around: depth (in) = cubic yards × 324 ÷ area (sq ft). For example, 2 cubic yards spread over 200 sq ft gives a layer about 3.2 in deep. In metric, depth (cm) = m³ × 100 ÷ area (m²).
How does the calculation work?
Tons = area × depth × density
Cubic yards = area (sq ft) × depth (in) ÷ 324
Tons = cubic yards × density (about 1.35 for gravel)
Cubic metres = area (m²) × depth (cm) ÷ 100
Tonnes = m³ × density (about 1.6 for gravel)
The calculator adds 10% on top for compaction and waste unless you untick it.
Driveway, 40 ft by 10 ft, 3 in deep: 400 sq ft × 3 ÷ 324 = 3.7 cubic yards. At 1.35 tons per cubic yard that is 5 tons, or 5.5 tons with the 10% allowance.
Drive in metric, 12 m by 3 m, 7.5 cm deep: 36 m² × 7.5 ÷ 100 = 2.7 m³. At 1.6 tonnes per m³ that is 4.3 tonnes, or 4.75 tonnes with the 10% allowance.
Step by step: gravel for a patio base
Circles and odd shapes
For a circle, area = 3.14 × radius × radius. A round fire pit area 10 ft across has a radius of 5 ft, so 3.14 × 5 × 5 = 78.5 sq ft. For an L shape or a curved border, split it into rectangles and circles, work out each area and enter the total in Total area.
Square feet, square yards and square metres
The calculator takes square feet or square metres. Square yards × 9 = square feet, and square metres × 10.76 = square feet. As a quick check, every square foot at 1 in deep needs about 8.3 lb of gravel, and every square metre at 5 cm deep needs about 80 kg.
Gravel coverage: how far does a ton or a yard go?
Coverage depends only on the depth. These figures use 1.35 tons per cubic yard, which is typical for dry crushed or pea gravel and works out to about 100 lb per cubic foot.
Coverage for larger orders
At 3 in deep, 2 tons covers about 160 sq ft, 5 tons about 400 sq ft, 10 tons about 800 sq ft and 20 tons about 1,600 sq ft. By volume, 5 cubic yards covers about 540 sq ft and 10 cubic yards about 1,080 sq ft.
Bags and bulk bags
A 50 lb bag holds about half a cubic foot and covers about 3 sq ft at 2 in deep. A 40 lb bag covers about 2.4 sq ft. In metric, a 20 kg bag covers about 0.25 m² at 5 cm and a 25 kg bag about 0.3 m².
One tonne of gravel covers about 12.5 m² at 5 cm deep, whether it is 10 mm or 20 mm stone. Bulk bags sold as tonne bags often hold less than a full tonne, commonly 800 to 900 kg, so check the weight on the bag before you work out how many to order.
Gravel conversions: tons, yards, cubic feet and m³
Two quick rules for typical gravel: cubic yards = sq ft × depth (in) ÷ 324, and tons = sq ft × depth (in) ÷ 240. So 20 tons of gravel is about 14.8 cubic yards, and 2 cubic yards weigh about 2.7 tons (5,400 lb).
Why wet gravel weighs more
Water fills the gaps between the stones, so a cubic yard of wet gravel can weigh about 1.6 tons. If gravel is weighed straight after rain, you get slightly less stone for each ton you pay for. Choose Wet gravel in the calculator to see the difference.
How much gravel do I need for a driveway?
A gravel driveway is built in layers. A compacted base of crusher run or road base carries the weight of the car, and a top layer of 3/4 in crushed stone gives a firm surface that drains. Work out each layer separately in the calculator, using the same area and a different depth and material.
Example: a driveway 12 ft wide and 50 ft long
Gravel driveway cost
Prices vary a lot between regions and types of stone, so the calculator does not assume one. Ask local suppliers for a price per ton or per cubic yard, including delivery, and enter it under Price to see the total. The same method works for a gravel parking area or a farm road: use the larger area and a deeper base.
Gravel for other projects
Patio and paver base
Most patios need a compacted base of 4 in (10 cm) under the pavers, and more on soft ground or where cars will park. Enter the patio area and choose Base layer under pavers. The Paver calculator counts the pavers.
Shed base
Make the gravel pad about 1 ft (30 cm) bigger than the shed on every side and 4 in (10 cm) deep. A 10 × 12 ft shed needs a 12 × 14 ft pad: 168 sq ft × 4 ÷ 324 = 2.1 cubic yards, about 2.8 tons.
French drains and trenches
Use trench length × width as the area and the trench depth as the depth. A trench 50 ft long, 1 ft wide and 18 in deep holds 50 × 18 ÷ 324 = 2.8 cubic yards of stone, about 3.8 tons, before the pipe goes in. The French drain calculator is set up for drains.
Retaining wall backfill
Most block walls need a band of clean drainage gravel about 12 in (30 cm) wide behind them. Use wall length × 1 ft as the area and the wall height as the depth. A wall 30 ft long and 3 ft high needs 30 × 36 ÷ 324 = 3.3 cubic yards, about 4.5 tons. Plan the wall itself with the Retaining wall calculator.
Fence post holes
Many fencers put about 6 in (15 cm) of gravel in the bottom of each post hole for drainage. For a hole 10 in wide, that is about a quarter of a cubic foot, or roughly 27 lb, per hole. Multiply by the number of posts.
Aquarium gravel
The calculator works for a fish tank too. Choose Length × width and enter the inside base of the tank in feet, set the depth, choose Pea gravel and untick the 10% allowance. A tank base of 30 × 12 in is 2.5 × 1 ft. At 2 in deep that is about 0.42 cubic feet, or roughly 42 lb of gravel.
Gravel for concrete
This calculator is for loose gravel. To mix concrete by hand, a common mix is 1 part cement, 2 parts sand and 3 parts gravel by volume. For the gravel base under a slab, enter the slab area and a base depth of about 4 in (10 cm). For sand, use the Sand calculator.
Ordering gravel: bulk or bags
Gravel is sold by the ton or by the cubic yard. Bags of 40 or 50 lb suit small repairs. For a driveway, order bulk and ask your supplier how much one truck carries so you can order full loads.
Compare prices on the same basis. A cubic yard of gravel fills about 54 bags of 50 lb or 68 bags of 40 lb, so bagged gravel usually costs much more per ton than bulk. Bags make sense for small jobs, top-ups and places a truck cannot reach.
Quarries and builders merchants often sell by the ton, while landscape yards often sell by the cubic yard. Use the conversions above to compare quotes. Many suppliers have a minimum delivery, so if you are close to a full load, round up.
Laying tips
Gravel calculator questions
How many tons of gravel do I need?
Multiply the area in square feet by the depth in inches and divide by 240. A 10 × 20 ft area at 3 in deep needs 200 × 3 ÷ 240 = 2.5 tons of typical crushed or pea gravel.
How many square feet does a yard of gravel cover?
About 162 sq ft at 2 in deep, 108 sq ft at 3 in and 81 sq ft at 4 in.
Does the calculator add extra for compaction?
Yes, when Add 10% for compaction and waste is ticked, which it is by default. Untick it if you want the exact volume, for example for a loose decorative layer.
Can I use it for crushed rock, crusher run or landscape rock?
Yes. Choose Crushed gravel for clean crushed rock and Road base with fines for crusher run, crush and run and other base mixes. For larger decorative stone, the Landscape rock calculator is set up for bigger stone.
Is this the same as other online gravel calculators?
Most online gravel calculators, including the Omni gravel calculator and the estimators on store websites, use the same method: area × depth × density. Results can differ slightly because each one assumes its own density. This calculator shows the density it uses, lets you change it, and gives tons, cubic yards, bags and cost together, in US or metric units.