How much potting soil does a 12 inch pot need?

A straight-sided cylinder with a 12 inch inside diameter and 10 inch fill height holds 5π/24 cubic feet, approximately 0.65 cubic feet or 19 litres. Three such cylinders hold 5π/8 cubic feet and need 2 bags of 1.5 cubic feet; six need 3 and ten need 5. Enter a positive whole count to combine identical containers before rounding bags. These quantities do not include a plant or drainage displacement.

How much soil do the common pot sizes take?

The following are illustrative inside-diameter and fill-height pairs, not a standard pot catalogue: 6 by 5 inches gives about 0.08 cubic feet; 8 by 7 gives 0.20; 10 by 9 gives 0.41; 12 by 10 gives 0.65; 14 by 12 gives 1.07; 16 by 14 gives 1.63; 20 by 16 gives 2.91; and 24 by 20 gives 5.24. Each assumes a straight-sided cylinder. Actual containers need their measured internal geometry.

How many pots will one bag of potting mix fill?

This page calculates the bags needed for a supplied whole count of identical cylinders. It has no inverse workflow that accepts a bag quantity and returns how many containers it fills. Bag counts use the full combined volume before rounding, so a 1.5 cubic foot bag covers the combined geometric volume of two 12 by 10 inch cylinders, while three cylinders need 2 bags. Rounded displayed pot volumes must not be used for a precise inverse calculation.

Does the calculator allow for the pot tapering and for the plant?

No. The drawing and arithmetic describe straight-sided cylinders. It does not accept bottom diameter, a taper profile, plant/root-ball volume or drainage displacement. A cylinder calculation cannot establish a numerical range for an unspecified container or plant. Measure or obtain the relevant shape and displacement data for those separate jobs.

Is potting mix measured in litres or cubic feet?

The calculator displays litres, cubic feet, cubic yards and cubic metres. Choose L for a bag capacity printed in litres and type that capacity directly, such as 40 or 50. One cubic foot is exactly 28.316846592 litres, so entering a rounded 1.41 cubic foot substitute for 40 litres changes the supplied bag. Diameter and fill height can be inches or centimetres; their units are independent of bag capacity.

Potting Soil Calculator

A 12 inch pot filled with 10 inches of mix takes 0.65 cubic feet, which is about 19 litres, so one 1.5 cubic foot bag fills two of them with a little left over. This page presents Pot mode and measures identical straight-sided cylinders from an inside diameter, fill height and positive whole count. It combines their full volume before rounding bags, using the capacity you supply in cubic feet, litres or cubic metres. Cylinder decimal quantities are marked approximate; complete pi bounds and any uncertain bag range are available below. Taper, plants and drainage displacement are separate inputs this workflow does not accept.

Soil needed12 in across, 10 in mix, 1 pots

Cubic feet≈ 0.65

≈ 0.02 cu yd · ≈ 18.53 litres · ≈ 0.02 m³1 bags at 1.5 ft³, rounded up

≈ 0.07 m² combined plan area × 10 in = ≈ 0.02 m³; bag division uses the full combined volume.

Supply your measured space, chosen fill depth and the capacity printed on your bag. Pot mode measures identical straight-sided cylinders using an inside diameter and fill height; it does not model taper or a plant. The initial dimensions and 1.5 ft³ bag are editable examples. Plan, depth and bag units are independent. Unit changes preserve measurements as exact decimals or fractions. Results round to two decimal places; ≈ marks a cylinder approximation and … marks an abbreviation. Complete values are below.

Complete selectable calculation

Soil Calculator - supplied quantity estimate
Mode: pot; 12 in inside diameter at 10 in of mix, 1 identical cylinders
Supplied bag capacity: 1.5 ft³
Combined cylinder plan area: π × 145161/6250000 m²
Combined cylinder volume: π × 18435447/3125000000 m³
Combined plan area: between 4560367311877479762884757761602359181729453071826897360785439319639949373529123844498441632814870556934319/62500000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 and 114009182796936994072118944040058979543236326795672434019635982990998734338228096112461040820371763926987/1562500000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 m²; approximate ≈ 0.07 m²
cubicMetres: between 579166648608439929886364235723499616079640540122015964819750793594273570438198728251302087367488560730658513/31250000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 and 14479166215210998247159105893087490401991013503050399120493769839856839260954968206282552184187214018727349/781250000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 m³; approximate ≈ 0.02 m³
cubicFeet: between 10471975511965977461542144610931676280657231331250352736583148641026054687620696662093449417807056893/16000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 and 785398163397448309615660845819875721049292349843776455243736148076954101571552249657008706335529267/1200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ft³; approximate ≈ 0.65 ft³
cubicYards: between 10471975511965977461542144610931676280657231331250352736583148641026054687620696662093449417807056893/432000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 and 785398163397448309615660845819875721049292349843776455243736148076954101571552249657008706335529267/32400000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 yd³; approximate ≈ 0.02 yd³
Litres: between 579166648608439929886364235723499616079640540122015964819750793594273570438198728251302087367488560730658513/31250000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 and 14479166215210998247159105893087490401991013503050399120493769839856839260954968206282552184187214018727349/781250000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 L; approximate ≈ 18.53 L
Whole bags: 1
A supplied rectangular space or known area and chosen fill depth, or identical straight-sided cylindrical containers with an inside diameter, fill height and exact positive whole count. Defaults are editable examples, not suitable depths or product recommendations.
Rectangle and known-area arithmetic and unit conversions are exact. Cylinders are π times the stated coefficient; decimal displays use a 100-place bound for π and are approximate. A bag range means that bound straddles a whole-bag boundary.
Bag counts round up from the full combined volume before display rounding. Large previews are abbreviated; this report retains complete values. Litres are exactly 1000 times cubic metres.
No taper, root-ball displacement, drainage, settling, compaction, weight, soil mix, material suitability, supplier, delivery or price is inferred. Separately rounded bag counts do not establish the ceiling for a combined job.

A 4 by 8 raised bed10 in of mix
26.67 cu ft · 18 bags at 1.5 ft³
A hole to fill3 ft by 3 ft, 2 ft deep
18.00 cu ft · 12 bags at 1.5 ft³
A 12 in round pot10 in of mix
≈ 0.65 cu ft · 1 bags at 1.5 ft³

Supplied quantities and complete working. Exact arithmetic for length by width by depth or known area by depth, with quantities converted without rounding until the last step. The cylinder formula for a pot uses a bounded approximation of pi; a bag-count range marks an uncertain boundary. It cannot know how far soil settles after its first watering, how much room root balls take, or what a brand actually puts in a bag. Open the complete calculation for exact quantities, cylinder bounds and the assumptions used.

Common questions

How much potting soil does a 12 inch pot need?: A straight-sided cylinder with a 12 inch inside diameter and 10 inch fill height holds 5π/24 cubic feet, approximately 0.65 cubic feet or 19 litres. Three such cylinders hold 5π/8 cubic feet and need 2 bags of 1.5 cubic feet; six need 3 and ten need 5. Enter a positive whole count to combine identical containers before rounding bags. These quantities do not include a plant or drainage displacement.
How much soil do the common pot sizes take?: The following are illustrative inside-diameter and fill-height pairs, not a standard pot catalogue: 6 by 5 inches gives about 0.08 cubic feet; 8 by 7 gives 0.20; 10 by 9 gives 0.41; 12 by 10 gives 0.65; 14 by 12 gives 1.07; 16 by 14 gives 1.63; 20 by 16 gives 2.91; and 24 by 20 gives 5.24. Each assumes a straight-sided cylinder. Actual containers need their measured internal geometry.
How many pots will one bag of potting mix fill?: This page calculates the bags needed for a supplied whole count of identical cylinders. It has no inverse workflow that accepts a bag quantity and returns how many containers it fills. Bag counts use the full combined volume before rounding, so a 1.5 cubic foot bag covers the combined geometric volume of two 12 by 10 inch cylinders, while three cylinders need 2 bags. Rounded displayed pot volumes must not be used for a precise inverse calculation.
Does the calculator allow for the pot tapering and for the plant?: No. The drawing and arithmetic describe straight-sided cylinders. It does not accept bottom diameter, a taper profile, plant/root-ball volume or drainage displacement. A cylinder calculation cannot establish a numerical range for an unspecified container or plant. Measure or obtain the relevant shape and displacement data for those separate jobs.
Is potting mix measured in litres or cubic feet?: The calculator displays litres, cubic feet, cubic yards and cubic metres. Choose L for a bag capacity printed in litres and type that capacity directly, such as 40 or 50. One cubic foot is exactly 28.316846592 litres, so entering a rounded 1.41 cubic foot substitute for 40 litres changes the supplied bag. Diameter and fill height can be inches or centimetres; their units are independent of bag capacity.

Exact arithmetic for length by width by depth or known area by depth, with quantities converted without rounding until the last step. The cylinder formula for a pot uses a bounded approximation of pi; a bag-count range marks an uncertain boundary. It cannot know how far soil settles after its first watering, how much room root balls take, or what a brand actually puts in a bag.