TryBuildCalcHow Much Artificial Grass Do I Need? (Real Strip Layout Off a Fixed-Width Roll)
Find how much artificial grass to buy from a real strip layout, not area plus 10%.
🕒 Last updated: September 24, 2026
Inputs
Lawn Areas
Applies to every dimension on this form — lawn sizes in feet, and pile height, base depth and fastener spacing in inches. Switching converts the figures already entered rather than reinterpreting them.
ℹ️Sets a sensible starting point for the pile height, the infill type and rate, and the base depth — all of which you can then change. On a hard surface it also switches the whole installation to a bonded one, because there is nothing to nail into.
The default case: a decorative or lightly-used lawn. Published guidance puts residential infill at roughly 1-2 lb/sq ft, and a base at 3-4 in of compacted aggregate; 4 in is used here as the safer starting figure.
Area List
Add a row per rectangle. An L-shaped or curved lawn is best entered as the two or three rectangles it breaks into, measured to the widest point of each — that is how the turf gets cut anyway.
Area 1
Turf & Strip Layout
ℹ️The most important figure on this form. Turf is cut to length off a roll of fixed width, so the width decides how many strips your lawn needs and how much you pay for turf you cannot use. Check the actual roll width with your supplier before ordering.
ℹ️Most suppliers cut to length, so you pay for the linear metres or feet you need. Some sell full rolls only, in which case the order rounds up to whole rolls and the leftover is yours.
ℹ️Synthetic grass blades lean one way down the roll, so every strip in one continuous area must run the same way or the joint reads as a change of shade. That makes the running direction a single decision for the whole area — and it can change how much turf you buy by tens of percent.
Works out both directions for every area and uses the cheaper one, then tells you what the other would have cost. On an area whose width sits just over a roll width this is frequently a 15-30% difference in turf bought.
ℹ️The blade length. It sets how much infill is needed to hold the blades up, and it adds to the build-up depth you have to excavate for so the finished lawn sits flush with its edging.
ℹ️Spare length left at each end of every strip so it can be trimmed square to the edge. Added to both ends of each strip. Enter 0 to cut every strip exactly to length with nothing in hand.
ℹ️Extra on top of the strip layout, for trimming to curves, cutting around a tree or a manhole, and the piece that gets cut wrong. This is separate from the roll-width waste, which the layout already works out exactly — around 5% suits a simple rectangular lawn, 10% one with obstacles and curves.
When several areas each end in a narrow strip, those narrow pieces can be cut side by side out of one length of roll instead of one length each — they all still run with the pile, so it is a legitimate cut rather than a rotated offcut. Leave this off to keep each area on its own strips, which is simpler on site and harder to get wrong; turn it on to get the shared cut list and a smaller order.
Ground Preparation
A graded blend of crushed rock and fines — the same material used under roads. The default all-purpose choice: the fines let it lock up hard under a compactor while the coarse fraction carries the load.
ℹ️The depth AFTER compaction — the finished thickness under the turf. Published guidance puts a residential turf base at 3-4 in (75-100 mm), deeper for pets, heavy rain or vehicle loads.
ℹ️How much of its loose volume the aggregate loses under the compactor, typically 15-20%. The order is worked out by DIVIDING by what is left, not multiplying by the loss — at 20% you need 25% more loose material, not 20%.
ℹ️A thin fine layer screeded over the coarse base, because a graded sub-base cannot be levelled to the flatness a turf surface wants. Usually 0.5-1.5 in (12-40 mm). Its depth counts toward the excavation as well.
The usual position for a weed membrane: it blocks light so nothing germinates in the base, and it sits where you can still pin it down through the turf's fasteners.
ℹ️Membrane strips have to overlap rather than butt, or weeds find the joint. The overlap comes off each strip's effective width, so a 6 ft roll lapped 6 in covers 5.5 ft — which is why dividing the lawn area by the roll area comes up short.
Infill
ℹ️Infill weighs the turf down, holds the blades upright, shields the backing from UV and carries heat away. It is also the heaviest thing in the order by a wide margin, so it is bought by weight.
The default, and the cheapest by a distance. Rounded, kiln-dried grades flow between the blades instead of bridging; a sharp or unwashed sand packs and holds water. Published rates run about 1-2 lb/sq ft for a short residential pile and 2-3 lb/sq ft for a 1-2 in pile. Typical rate: 1-3 lb/sq ft.
ℹ️How much infill goes down per unit of lawn. Always check the turf manufacturer's own figure for your pile height — infill should sit in the bottom of the pile supporting the blades, not bury them. The result flags a rate that would do either.
Seams & Fixing
ℹ️The seam quantities come straight out of the strip layout, because a seam is exactly where two strips meet. If every area fits inside one roll width there are no seams at all and none of this is needed.
The standard, strongest method: 12 in wide tape run under the joint, adhesive troweled or gunned onto it, the two turf edges dropped on and weighted. Nothing penetrates the turf face, so the seam stays invisible.
5 in to 6 in galvanised or bright common nails (40D-60D) driven through the turf backing into the compacted base. The standard method wherever there is a base to nail into.
ℹ️The edge is where turf lifts, so this is the spacing that matters. Published guidance puts it at every 3-6 in (75-150 mm), tightening toward 3 in on an exposed edge. Counted fence-post style: one at each end of every run as well as those between.
ℹ️Most residential lawns are fastened only at the perimeter and seams, because the infill weight is what holds the middle down. A grid through the field is used on pet runs, play areas and anywhere the turf gets pulled at.
ℹ️Seam adhesive is quoted by the LINEAR foot of 12 in tape, not by area. A 5 gallon bucket covers roughly 250 linear ft, a 1 gallon pail about 50, and a 29 oz cartridge about 13.
Bends to a curve, which is what makes it the usual choice for a shaped lawn. Staked at roughly 3 ft centres.
Cost Estimation
Artificial Grass to Order
34.3 ft
10.5 m off a 15 ft (4.57 m) wide roll
Turf Area Bought
514.5 sq ft
47.8 m² / 57.2 sq yd, to cover 320 sq ft of lawn
20 ft x 16 ft lawn — 2 strips, 1 seam
16 ft (4.9 m) of seam to join, and 72 ft (22 m) of perimeter to fix down.
Strips run along the width: 2 strips of 16.33 ft off a 15 ft wide roll.
The last strip only needs 5 ft of its 15 ft width, leaving a 10 ft x 16.33 ft offcut. You still buy the whole width, because the pile has to run the same way in every strip.
Where the Extra Turf Goes
| Lawn actually covered | 320 sq ft | 29.7 m² |
| Roll width bought but not covered Pure geometry: you buy whole roll widths, and the last is usually partial. The one component a layout change can remove. | +160 sq ft | 50% of the lawn |
| End trim at each strip end An allowance you set, not waste — spare length to cut square to the edge. | +10 sq ft | 490 sq ft running total |
| Cutting and fitting allowance (5%) For curves, obstacles and the piece that gets cut wrong. | +24.5 sq ft | - |
| Turf bought | 514.5 sq ft | 60.8% over the lawn area |
An area-based turf calculator reports only the last line as a flat 10% and misses the roll-width component entirely — which on this job alone is 160 sq ft.
Strip direction changes the order
Running the strips the other way round would have needed 120 sq ft more turf (11.2 m²). The cheaper direction was chosen for each area — set it out that way on site.
Ground Preparation
Excavate to: 6.75 in (17.1 cm) — 4 in of base plus 1 in of levelling course plus 1.5 in of turf and backing, so the finished lawn sits flush with its edging
Spoil to remove: 6.7 cu yd in the ground, bulking up to roughly 8-8.7 cu yd once dug
Class II road base / crushed aggregate base, compacted volume: 4 cu yd (106.7 cu ft / 3 m³)
Order loose (+20% compaction): 4.9 cu yd = 6.9 US tons / 6.2 tonnes
Decomposed granite / crusher fines levelling course: 1.2 cu yd loose (1.7 US tons / 1.5 tonnes)
The loose volume is the compacted volume DIVIDED by (1 - 20%), not multiplied by (1 + 20%). Multiplying gives 4.7 cu yd, which is short — a mistake that leaves you a fraction of a load light at the very end of the job. Aggregate density is taken as 1.39 US tons per cubic yard loose; confirm it with your own supplier, since it varies with grading and moisture.
Infill
Kiln-dried silica sand (rounded) at 1.5 lb/sq ft (7.32 kg/m²): 480 lb / 218 kg (0.2 US tons)
That is 10 x 50 lb bag, about 4.8 cu ft of material, sitting roughly 0.18 in deep — 12% of the 1.5 in pile
Spread over the 320 sq ft of lawn, not the 514.5 sq ft of roll bought — offcuts never get infilled. Volume is estimated from a typical loose density of 100 lb/cu ft for this material; the purchase figure is always the weight.
Seams, Fixings & Accessories
Seam tape: 1 x 12 in x 328 ft (100 m) roll for 16 ft of seam
Adhesive: 1 x 5 gallon bucket at 250 linear ft of seam per pack
Galvanised turf nails / spikes: 217 (1 pack of 250) — 217 around the perimeter at 4 in centres
Weed barrier: 1 roll of 6 ft x 300 ft — 60 ft of strip, over the base, directly under the turf
A 6 ft roll lapped 6 in covers only 5.5 ft per strip, which is why dividing the lawn area by the roll area comes up short — that method would have given 1 roll.
Bender board (flexible plastic or composite): 4 x 20 ft for 72 ft of perimeter, plus about 25 stakes
Assumptions Used
Each area is laid out as whole strips cut off a 15 ft wide roll, with every strip in an area running the same way, because synthetic grass blades lean one way down the roll and a rotated strip reads as a different shade of green. That is why a partial last strip still costs a full roll width, and why offcuts are never rotated to fit. Each area's running direction was chosen to buy the least turf, with less seam breaking a tie. Seam length is taken as the full length of every joint between strips, which is where the tape, adhesive and seam-fastener quantities come from. Base aggregate, infill and any barrier or shock pad are sized on the 320 sq ft of lawn actually covered; turf is sized and priced on the 514.5 sq ft of roll bought. Base aggregate is ordered loose, as the compacted volume divided by (1 - 20%), and converted to weight at a typical loose density rather than an exact one. Every whole-unit count — strips, rolls, bags, packs, boards — rounds up from unrounded values. This calculator estimates material quantity only. It does not design a drainage scheme, certify a playground fall height, assess subgrade bearing, or account for tree roots, service runs or existing structures.
Bill of Materials
Main material: 34.3 linear ft + recommended tools
+−
Bill of Materials
Main material: 34.3 linear ft + recommended tools
Computed quantities come from your own areas, roll width and material settings above; the consumables below are general recommendations, filtered to this installation — actual needs vary by product, ground conditions and site access.
For Your Job
Artificial grass
Base aggregate — Class II road base / crushed aggregate base
Levelling course — Decomposed granite / crusher fines
Weed barrier / geotextile
Infill — Kiln-dried silica sand (rounded)
Seam tape
Turf adhesive
Galvanised turf nails / spikes
Perimeter edging — Bender board (flexible plastic or composite)
General Tools & Consumables
Utility knife and plenty of spare blades
Chalk line or marking paint
Tape measure (long, 100 ft / 30 m)
Stiff broom, or a power broom for anything sizeable
Wheelbarrow
Gloves and knee pads
Groundwork & Base
Plate compactor (hire)
Spade, shovel and landscaping rake
Screed bar or straight timber, plus a level
Skip, grab lorry or spoil removal
Drainage aggregate, channel or French drain
Seaming
Notched trowel or caulking gun
Seam roller or weights (sandbags, boards)
Disposable gloves and a solvent wipe
Fixing Down
Claw hammer or rubber mallet
Carpet kicker or turf stretcher
Infill
Drop spreader
Plan drawn to the proportions of the dimensions entered, divided into the actual strips the layout needs; arrows show the pile direction every strip has to share, dashes mark the seams, and hatching marks roll width bought beyond the lawn edge. End trim at each strip end is included in the order but not drawn. Section layers are proportional to their real depths, with a minimum thickness so thin layers stay legible.
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Artificial Grass / Synthetic Turf Calculator.
Turf is bought by the strip, not by the square foot
The reason a turf order surprises people is that artificial grass is not a bulk material. It is a manufactured sheet of fixed width — most commonly 15 ft, with 12 ft, 4 m and 2 m also stocked — cut to length off a roll. You buy whole roll widths, so a lawn 16 ft across a 15 ft roll needs a second strip and you pay for the other 14 ft of that strip too. A 20 ft by 16 ft lawn is 320 sq ft of grass, but laid as two 20 ft strips it takes 600 sq ft of roll: 87% over, not 10%.
Which way the strips run changes it again. The same lawn laid as two 16 ft strips running the other way takes 480 sq ft — 120 sq ft less turf for exactly the same lawn. What you cannot do is mix the two, because synthetic grass blades lean one way down the roll and a rotated strip reads as a different shade of green. This calculator plans the strips both ways round, keeps every strip in one area running the same way, and tells you which direction is cheaper and by how much.
Artificial Grass Formula & Method
Every figure is computed in feet, square feet, cubic feet and pounds, and converted only for display. Feet is the natural working unit because the governing quantity — roll width — is a fixed manufactured dimension, and because the layout is an integer count of those widths across a measured area.
Step 1 — Strip layout, per area
For strips running along dimension A, across dimension B:
strips = ROUNDUP( B / roll width )
strip length = A + 2 x end trim
roll length = strips x strip length
turf area = roll length x roll width
lawn area = A x B
seams = strips - 1
seam length = seams x A
width waste = (strips x roll width - B) x A
The ROUNDUP is the whole point. You buy whole roll widths, so a 16 ft wide lawn off a 15 ft roll takes two strips and you pay for the other 14 ft of the second strip. That is not a waste allowance, it is geometry — and it is reported separately from the cutting allowance for exactly that reason. Note that the seam runs the length of the AREA, not of the over-long strip.
Step 2 — Which way the strips run
Option 1: strips along the length
A = length, B = width
Option 2: strips along the width
A = width, B = length
Choose the option with the smaller turf area;
if equal, the one with less seam.
CONSTRAINT: every strip in one continuous area
must run the SAME way (pile direction).
Synthetic grass blades lean one way down the roll, so a strip laid at ninety degrees to its neighbour reads as a different shade of green from most angles — the same effect as nap on a carpet. That constraint is what makes the running direction a single decision for the whole area, and it is why the usual offcut-rotating tricks from tiling and flooring are unavailable here. On a lawn whose width sits just past a roll width, swapping the direction frequently changes the turf bought by 15-30%.
Step 3 — The whole job, and the allowances
roll length = sum over areas of
(strips x strip length x count)
order length = roll length x (1 + cutting% / 100)
order area = order length x roll width
whole rolls = ROUNDUP( order length / roll length )
Over-purchase, split into its three causes:
width waste — geometry, removable by layout
end trim — an allowance you set
cutting % — curves, obstacles, mistakes
Splitting the over-purchase matters because only the first component can be designed out. A single blended waste percentage hides the fact that a lawn a foot over a roll width is paying for a whole extra strip, which a small change to the layout would delete entirely. The cutting allowance is genuinely separate: around 5% for a simple rectangle, nearer 10% with curves and obstacles.
Step 4 — Base aggregate and excavation
compacted volume = lawn area x compacted depth
loose volume = compacted volume
-------------------------
(1 - compaction% / 100)
weight = loose volume x loose density
excavation depth = base depth
+ levelling course depth
+ pile height + backing
spoil (bulked) = in-situ volume x 1.20 to 1.30
The division is the part published turf calculators get backwards. At 20% compaction the loose volume needed is 25% more than the compacted volume, not 20% more — multiplying leaves the order about 4% short, which is enough to stop the job at the final lift. Excavation is the full build-up, not just the base: getting that wrong is the commonest reason a finished artificial lawn stands proud of its own edging. Dug soil bulks up, so size the skip on the bulked figure, not the hole.
Step 5 — Weed barrier, in overlapping strips
effective width = roll width - overlap
strips = ROUNDUP( area width / effective width )
length = strips x area length x layers
rolls = ROUNDUP( length / roll length )
layers = 2 for a separation layer below the base
AND a weed membrane above it
A membrane is also a fixed-width roll laid in strips, with one difference: the strips must overlap rather than butt, or weeds find the joint. So a 6 ft roll lapped 6 in contributes only 5.5 ft per strip, and dividing the lawn area by the roll's nominal area comes up short. Unlike turf, a membrane has no pile direction, so its strips are always run whichever way needs fewer of them.
Step 6 — Infill, seams and fixings
infill weight = LAWN area x rate (lb/sq ft)
infill bags = ROUNDUP( weight / bag weight )
infill depth = (weight / density) / lawn area
tape rolls = ROUNDUP( seam length / roll length )
adhesive = ROUNDUP( seam length / linear ft per pack )
or, glued down:
= ROUNDUP( area / sq ft per pack
+ perimeter / linear ft per pack )
perimeter fasteners = ROUNDUP( perimeter / spacing ) + 1
per area
field fasteners = ROUNDUP( area / spacing² )
edging pieces = ROUNDUP( perimeter / piece length )
Infill goes on the lawn area, never the roll area — offcuts are never infilled, and on a job with heavy layout waste the difference is a whole pallet. Adhesive is the one line with two different bases: a seam bead is quoted per linear foot of 12 in tape, a full glue-down per square foot of surface, and using one for the other is out by an order of magnitude. Perimeter fasteners are counted fence-post style, one at each end of a run as well as those between, applied per area because each lawn is its own closed loop.
Worked Example
This example walks through your current inputs above, using the same steps as the Formula section.
Input Values Used
| Input | Value |
|---|---|
| Back lawn | 20 ft x 16 ft (6.1 m x 4.88 m) |
| Application | Lawn / general landscaping |
| Roll Width | 15 ft (4.57 m) |
| Strip Direction | Whichever wastes less (recommended) |
| Pile Height | 1.5 in (3.8 cm) |
| Allowances | 2 in end trim per strip end, plus 5% for cutting |
| Base | Class II road base / crushed aggregate base, 4 in compacted, 20% compaction |
| Infill | Kiln-dried silica sand (rounded) at 1.5 lb/sq ft (7.32 kg/m²) |
| Seam Method | Seam tape + turf adhesive |
Step 1 & 2 — Strip Layout, Both Directions
| Area | Calculation | Result |
|---|---|---|
| Back lawn | ROUNDUP(20 / 15) = 2 strips of 16 + 2 x 0.17 = 16.33 ftThe other way round: 2 strips, 610 sq ft of turf | 490 sq ft of roll, strips along the width last strip uses 5 ft of its 15 ft width |
| Whole job | 2 strips across 1 area | 32.7 ft of roll = 490 sq ft |
Step 3 — Turf to Order, and Where the Extra Goes
| Calculation | Result |
|---|---|
| Lawn actually covered | 320 sq ft (29.7 m²) |
| (2 strips x 15 ft of width) less the lawn width, over the run | +160 sq ft roll-width waste (50%) |
| 2 strips x 2 x 2 in of end trim x 15 ft | +10 sq ft end trim |
| 32.7 ft x (1 + 5% cutting allowance) | 34.3 ft of roll |
| Order | 34.3 linear ft (10.5 m) = 514.5 sq ft bought, 60.8% over the lawn |
Step 4 — Base Aggregate and Excavation
| Calculation | Result |
|---|---|
| 320 sq ft x 4 in / 12 | 106.7 cu ft compacted (4 cu yd) |
| 106.7 / (1 - 20%) | 4.9 cu yd loose to order multiplying instead of dividing would have given 4.7 cu yd — short |
| 133.3 cu ft x 103 lb/cu ft | 6.9 US tons (6.2 tonnes) |
| 320 sq ft x 1 in / 12, then / (1 - 20%) | 1.2 cu yd of decomposed granite / crusher fines (1.7 US tons) |
| 4 in base + 1 in levelling + 1.5 in pile + 0.25 in backing | excavate 6.75 in (17.1 cm) |
| Spoil, bulked 20-30% once dug | 8-8.7 cu yd to cart away |
Step 5 & 6 — Infill, Seams and Fixings
| Calculation | Result |
|---|---|
| 320 sq ft x 1.5 lb/sq ft | 480 lb (218 kg / 0.2 US tons) of kiln-dried silica sand (rounded) |
| ROUNDUP(480 / 50) | 10 x 50 lb bag |
| (480 lb / 100 lb/cu ft) / 320 sq ft | 0.18 in deep — 12% of the 1.5 in pile |
| 1 seam x their strip runs | 16 ft of seam (4.9 m) |
| ROUNDUP(16 / 328) | 1 x 12 in x 328 ft (100 m) roll |
| ROUNDUP(16 / 250) | 1 x 5 gallon bucket of adhesive |
| ROUNDUP(72 ft / 0.33 ft) + 1 per area | 217 galvanised turf nails / spikes — 1 pack of 250 |
| Strips at (6 - 0.5) = 5.5 ft effective width, then ROUNDUP(60 / 300) | 1 roll of barrier (60 ft of strip) |
| ROUNDUP(72 / 20) | 4 x 20 ft of bender board (flexible plastic or composite), about 25 stakes |
Figures above are rounded for display; the real quantities are always calculated from full, unrounded values.
Therefore, covering 320 sq ft of lawn (29.7 m²) takes 34.3 linear ft of 15 ft wide turf — 514.5 sq ft bought, 60.8% over the lawn area — laid as 2 strips with 1 seam, over 6.9 US tons of base, with 10 bags of infill.
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.