Mulch Calculator
A good layer of mulch suppresses weeds, locks in soil moisture through dry spells, and gives borders and beds a neat, finished look — whether you choose bark, woodchip, or compost mulch depends on whether you want a long-lasting decorative layer or something that feeds the soil as it rots down. Getting the depth right matters too: too thin and weeds push through, too thick and you risk smothering plants. Enter the area you want to cover below and we'll work out how many bags you need.
Work out how much mulch you need
Enter the area you want to cover and choose a mulch depth.
Topping up an established border
Enter an area above to see how much mulch you need.
Recommended products
A few well-reviewed options to help you prepare and maintain your beds.
£129.99
Pros
- Three-stage composting chambers
- Click-together assembly, no tools required
- Large 466L capacity suits big gardens
Cons
- Bulky — needs a dedicated corner
£219.00
Pros
- Rotating drum speeds up decomposition
- Elevated design deters pests and rodents
- No digging or turning by hand
Cons
- 190L capacity may be tight for larger households
£24.99
Pros
- Large 220L capacity at a low price
- Front hatch for easy compost access
- Lockable, air-tight lid
Cons
- Basic single-chamber design
- No aeration vents
Frequently asked questions
How often should I mulch?
Most UK gardens benefit from a fresh layer of mulch once a year, typically in spring after the soil has warmed up or in autumn to protect roots over winter. Bark and woodchip break down slowly, so topping up an existing layer to your target depth is usually enough rather than removing and replacing it entirely.
What is the best mulch for a UK garden?
Bark chippings are a popular all-rounder for borders and pathways, offering good weed suppression and a neat finish that lasts a couple of years. Woodchip is cheaper and great for informal areas but breaks down faster. Compost or well-rotted manure feeds the soil as it breaks down, making it a good choice around hungry plants, though it needs topping up more often.
Why does mulch depth matter?
Too thin a layer (under 5cm) lets light through and weeds still germinate. Too thick a layer (over 10cm) can smother plant roots, encourage rot around stems, and stop water reaching the soil properly. Sticking to 5-10cm depending on the job gives the best balance of weed suppression and moisture retention without harming plants.
Should I mulch right up to plant stems and tree trunks?
No — leave a small gap of a few centimetres around stems and trunks. Piling mulch directly against them traps moisture against the bark, which can lead to rot and encourages pests to shelter there.