How much mulch do I need?
Fresh mulch is the fastest before-and-after there is. Fill in your room, watch the answer move, then take the open math with you to the store.
How to tell if you are being overcharged
Mulch has a consumer protection rule behind it that almost nobody knows, and it is the single most useful thing on this page.
- NIST Handbook 130 requires all mulch to be sold by volume, in cubic yards or cubic feet. Nobody may lawfully sell it to you by the ton. That means a bag and a bulk yard are always directly comparable, and anybody quoting mulch by weight is either confused or hoping you are.
- The same handbook requires peat labeled in compressed cubic measure to declare the quantity in the compressed state. A bale expands after you open it and no published figure says how much, so a compressed bale and a loose bag are not the same purchase even at the same number.
- University of Illinois Extension puts the recommended depth at 2 to 4 inches and says outright that too much is harmful. Deeper is not better, it is just more money and worse drainage.
- Spreading mulch has no cut waste. There is nothing to cut. If somebody adds 10 percent for waste here, they are padding the order.
- Twenty seven cubic feet is a cubic yard, exactly. That is the only conversion this page needs and it comes from NIST Handbook 44.
The arithmetic, and the only number anybody can move on you
Bed length times bed width times depth. Depth arrives in inches, so divide it by twelve first. The twenty by four bed this page opens with, at three inches, is 80 square feet times 0.25 feet, which is 20 cubic feet. In two cubic foot bags that is ten bags. In cubic yards, using the 27 cubic feet to the yard printed in NIST Handbook 44, it is 0.74 of a yard.
Length and width you can measure and nobody can argue with. Depth is the only variable in the whole calculation, and it is the one that quietly doubles an order.
How much waste is technical here? None.
This is the shortest answer on the whole site. Spreading mulch has no cut waste. There is nothing to cut, nothing to trim, nothing that comes out of the bag unusable. The extra percentage field on this page starts at zero and it starts there on purpose.
If somebody adds ten percent for waste to a mulch order, ask what is being wasted. There is no answer that survives the question. The one honest reason to buy slightly over is that you would rather not drive back for a single bag, and that is a decision about your Saturday, not a technical allowance.
The point where a mulch quote stops adding up
Reverse it into depth, because depth is where the padding hides. Take the cubic feet quoted, divide by your bed's square footage, and multiply by twelve. You now have the depth in inches that person planned to lay.
University of Illinois Extension puts the recommended depth at two to four inches, splits it further as two to three inches for composted materials and three to four for coarse mulches, and says outright that adding too much mulch can be harmful. So the test is simple. If your quote implies five or six inches, you are not being sold generosity, you are being sold a problem: thick layers mat down and reduce water and oxygen reaching the soil, hold excess moisture in the root zone, cause decay, delay dormancy or bud break, and give rodents somewhere to live. That is the Extension's list, not an opinion.
The second test takes one sentence. If anybody quotes you mulch by the ton, something is wrong before you have looked at the price.
There is a regulation on your side at the register
NIST Handbook 130 carries the Uniform Regulation for the Method of Sale of Commodities, and section 2.18.2 says all mulch shall be sold, offered or exposed for sale in terms of volume measure: cubic meters or liters in metric, cubic yards or cubic feet in United States customary units. Not pounds. Not tons.
That single line is the most useful thing on this page, because it means a bag and a bulk yard are always directly comparable, and the comparison is arithmetic rather than negotiation. It also means the quantity on the bag is a legal declaration rather than marketing.
One boundary worth knowing. The same handbook defines mulch, in 2.18.1.1, as any product or material except peat or peat moss sold primarily as an aboveground horticultural dressing for decoration, moisture control, weed control, erosion control or temperature control. Peat has its own rule in section 2.5, and a bagged garden soil or bed mix is not mulch under this definition at all. So the volume rule you are leaning on here covers the bark and the wood chips. It does not automatically cover the bag of soil sitting next to them.
Bags against bulk, worked with your two prices
Twenty seven cubic feet is a cubic yard, exactly. Divide 27 by the cubic feet printed on your bag and you get the number of bags a yard replaces. For a two cubic foot bag that is 13.5. For a three cubic foot bag it is 9. For a one and a half it is 18.
Now the crossover, which is the question everybody actually has. Bulk is cheaper per cubic foot and arrives with a delivery fee, so the fee is what you are paying to avoid the bags. The break even is:
| Step | What you do |
|---|---|
| 1 | Work out bags per yard: 27 divided by the cubic feet on your bag |
| 2 | Multiply that by the bag price. This is what one yard costs you in bags |
| 3 | Subtract the bulk price of one yard from it. This is what you save per yard |
| 4 | Divide the delivery fee by that saving. That is how many yards you must be ordering before bulk wins |
If the saving per yard comes out at zero or negative, bulk never wins at that supplier and you can stop there. The fields above take both prices and the fee, so the page runs this on your numbers instead of on an average, and the answer changes by town, which is exactly why no site should print one.
The other half of the bulk decision is not money. A yard of mulch is dumped in one pile on your driveway and it is yours to move, whereas bags arrive in units a person can carry and store closed until next weekend. That is worth real money to some people and nothing to others.
How far one yard actually goes
Since a yard is 27 cubic feet, its coverage is just 27 divided by the depth in feet:
| Depth | One cubic yard covers | Extension guidance |
|---|---|---|
| 2 in | about 162 sq ft | bottom of the 2 to 4 range, and where composted material sits |
| 3 in | about 108 sq ft | inside the range for composted and for coarse |
| 4 in | about 81 sq ft | top of the range, and where coarse mulch sits |
Read that table sideways and you can see the whole economics of this page. Moving from three inches to four adds a third to your order and buys you nothing the Extension recommends.
The order that is often smaller than you think
Before you buy anything, the Extension's guidance says to check what is already there. If mulch is already present, check the depth, and if enough is present, refresh the appearance with a rake and break up the matted layers. That is a job with a rake and no receipt, and on an established bed it is frequently the correct answer.
The rest of the guidance is about placement rather than quantity, and it is worth having in your head while you spread:
- Apply mulch near but not touching the trunk, and keep it at least four inches away from it.
- If mulch is already piled against a trunk, pull it back several inches and expose the base. Mulch against the tree softens the bark and leads to insects, disease and girdling roots.
- Extend the layer out to the dripline or as far as you can. A three foot radius ring is the maximum for most trees, which is also a useful sanity check on how much area you are actually covering.
- Check under existing mulch to make sure rodents and other pests have not moved in.
What this page does not judge is quality. Dyed material, ground pallet wood and properly aged bark occupy the same cubic feet at very different prices and very different lifespans, and there is no public document comparing them that could honestly be cited here.
Questions people ask in the driveway
How many bags is a yard?
Thirteen and a half, if your bags are two cubic feet. Divide 27 by whatever your bag says.
Is bulk always cheaper?
Per cubic foot, usually. Delivered, only past the number of yards the four step calculation above gives you. For one small bed, bags frequently win.
How deep should it go?
Two to four inches, with composted materials at two to three and coarse mulches at three to four, per the Extension sheet. Deeper is not better.
Do I have to remove the old mulch first?
Not necessarily. Check the depth of what is there first. The guidance is to wait to replenish until it has decomposed, and to rake matted layers open rather than pile new material on top of them.
Why is my price quoted by weight?
It should not be. The uniform regulation requires volume. Ask for cubic yards or cubic feet and you are back on comparable ground.
The bag price above, and the one number this page still will not print
Volume is regulated and published. Depth is published by a land grant university. The bag price is read a third way, off product pages at Sutherlands, a home improvement and lumber chain out of Kansas City, Missouri whose pages publish a price for every one of its stores instead of one national number. Two bags were read on 2026-08-23:
- Sutherlands brown wood mulch, 2 cubic feet, item 7549918: 3.45 to 4.19 dollars across the 42 stores with it in stock. Open the product page.
- Sutherlands cedar mulch, 2 cubic feet, item 3759909: 3.45 to 4.95 dollars across the 35 stores with it in stock. Open the product page.
Read the caveat on this one twice, because mulch has the most seasonal price on the site. It swings with the season, the region and how far the material travelled, and it moves inside a single spring. One chain on one day in August is a starting point and nothing more. Type the tag in front of you into the price field and the whole page, the bags against bulk comparison included, reruns on your number.
And there is still one figure this page refuses to print, which is the price per cubic yard delivered in bulk. That is a quote from a yard, it depends on your address and the size of the load, and nobody publishes it anywhere a person could cite. The bulk field stays empty and yours, which is why the comparison above only appears once you have filled it in.
Sources. NIST Handbook 130 (2026), Uniform Regulation for the Method of Sale of Commodities, sections 2.18.1.1 and 2.18.2, doi.org/10.6028/NIST.HB.130-2026, opened 2026-08-23. NIST Handbook 44 (2026), Appendix C, nvlpubs.nist.gov, opened 2026-08-23. University of Illinois Extension, Proper Mulching Techniques, extension.illinois.edu, opened 2026-08-23. Sutherlands, the two product pages linked above, read 2026-08-23, for the bag price range.
The other calculators
Or start from the room instead
Nobody wakes up needing mulch and soil. Each room below opens with its own drawing, its own starting size and only the calculators that room needs.
What this page does not count. This page counts volume, and that is genuinely all mulch estimating is. What it does not do is tell you whether the mulch is any good. Dyed, ground pallet wood and properly aged bark chips occupy the same cubic feet at very different prices and very different lifespans, and nobody publishes a comparison you could cite.
An estimate, not a quote. Everything above is arithmetic on the measurements you typed and on figures printed in the documents cited on this page. The label on the product in your hand outranks all of it, which is why every one of those fields stays editable.