Topdressing Calculator
Topdressing Calculator UK
Work out exactly how much topdressing you need
For levelling, smoothing out bumps and hollows, or a light dressing after scarifying and overseeding. Draw your lawn on the map or enter your area manually.
Built with 30+ years of professional turf experience
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Topdressing Calculator
Based on your lawn measurements
Your Lawn Area
0
square metres
How Deep Are You Dressing?
Light Dressing
After scarifying or overseeding
3 mm
Standard Dressing
The usual once-a-year job
5 mm
Levelling
Bumps, hollows and uneven ground
8 mm
mm
You need
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—
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cubic metres
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25kg bags
(approx)
(approx)
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bulk bags
(approx)
(approx)
Cost Estimator
£
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£
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Change the prices to match your supplier. For anything over about 15 bags, a bulk bag is normally the cheaper way to buy it.
Topdressing and Seed Go Together
Most people topdress right after scarifying and overseeding. The dressing holds moisture around the seed and gives it something to root into. Feed the seed properly and the whole job comes together.
Seed & Establish Pro
Pre-seeder fertiliser — high phosphorus drives root development in new seedlings. Apply before or at sowing, then dress over the top.
Seaweed Lawn Booster
8% Ascophyllum nodosum — feeds the soil life in your new dressing and helps roots move into it faster. Feeding the soil, not just the lawn.
Topdressing Depth Guide
1mm of dressing over 1 square metre is 1 litre. That's the whole sum. Here's what the common depths look like in practice.
| Job | Depth | Litres per m² | When |
|---|---|---|---|
| Light dressing after scarifying / overseeding Most Common |
2–3 mm | 2–3 L | Spring or early autumn, straight after seeding |
| Standard annual dressing | 4–5 mm | 4–5 L | Once a year, when the grass is growing strongly |
| Levelling bumps and hollows | 6–10 mm | 6–10 L | Split into two or three goes if it's deeper than 10mm |
| Golf and bowling greens | 1–2 mm | 1–2 L | Little and often through the growing season |
Never bury the grass. If the leaf tips are covered, you've gone too deep — brush it in until the grass is showing through again.
Topdressing Questions, Answered
A 70/30 sand and soil mix is the safe bet for most lawns — it drains well and levels easily. Pure sharp sand is fine on sandy, free-draining lawns but can leave a hard, dry layer on heavy clay if you overdo it. Avoid builder's sand and anything with lumps in it.
When the grass is growing hard enough to push up through it — mid-spring to early autumn. September is the sweet spot if you're doing it with a scarify and overseed. Don't topdress a dormant lawn in winter; the dressing just sits on top and smothers it.
No more than about 10mm at a time, and the grass must still be showing through when you're done. Bigger hollows get filled in two or three visits a few weeks apart, so the grass grows up through each layer.
Tip small piles across the lawn, then work it in with the back of a rake, a lute or a stiff brush. Go in two directions. It's far easier on a dry day with the grass cut short first.
Yes, and it's the best way to do it. Scarify, apply Seed & Establish Pro, sow the seed, then a light 2–3mm dressing over the top. The dressing keeps moisture around the seed and gets it in contact with soil.
The volume is simple maths and it's spot on. Bag counts are approximate, because topdressing density varies with how sandy and how wet it is. Uneven lawns with plenty of hollows will need more. Always order a little extra.
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