Last checked
May 12, 2026
We checked the page logic, support notes, and related links on this page.
Aggregate and Base Estimating
How much sub-base should you order for a patio, path, or drive?
A better sub-base order starts with the real paved footprint and compacted depth, then checks whether bulk bags or loose tonnes make more sense for the site.
How to use it
Planning before buying
Use this guide for a planning check, then confirm the final order or quote against live product data and site conditions.
Why trust it
See how the site is maintained
Read the calculator methodology and editorial policy for the standards behind these pages.
Quick answer
Work out how much sub-base you need, then sense-check tonnes, compaction, and merchant delivery options.
When this guide helps
Turn the paved footprint and compacted layer depth into a safer sub-base order before the merchant quantity is locked in.
Watch most
Compacted depth, density, edge thickening, and formation corrections usually move the final sub-base order most.
Best next move
Pressure-test the compacted build-up first, then compare whether MOT Type 1, hardcore, bulk bags, or loose tonnes suit the job best.
Use the calculator first
Start with Sub-Base Calculator for the first number, then use this page to pressure-test pack sizes, spare stock, linked materials, and the parts of the order that usually get missed.
What this page adds after the maths
It moves from the neat measured result into the real buying decision: pack size, stock length, spare allowance, linked materials, and what should still be checked before ordering.
Buying assumption to keep straight
Sub-base estimates work best when the footprint, compacted layer depth, and the intended base specification are clear before the order is placed.
Common buying miss
The common misses are underestimating the depth needed for the build, ignoring soft spots or level corrections, and confusing loose-delivered tonnage with the compacted finished layer.
Buying decisions after the maths
These are the choices that usually change the real order once the first quantity is roughly right.
Type 1 route vs general fill route
A cheaper fill layer is not always the right choice once load, compaction, and the final paved surface are taken seriously.
Bulk bag route vs loose route
Bulk bags can simplify domestic access, while loose tonnes can make more sense once the footprint grows and spreading is straightforward.
Tight maths vs corrected formation
Straight footprint maths is useful, but weak spots and level corrections often justify a more conservative order.
Where buying totals usually move
Use these examples to see where pack size, spare stock, or linked materials push the final order.
Simple patio or path
Straight footprints usually give the cleanest sub-base estimate, but the compacted depth and edge detail still need checking.
Driveway or heavy-use base
Larger, deeper builds can move quickly once the footprint, compaction, and chosen grade are pressure-tested together.
Build-up check
Sub-base often sits alongside membrane, bedding sand, and edging, so the base quantity is rarely the only material decision in play.
Practical checks before you buy or brief
Use these prompts to move from a neat guide answer into a cleaner real-world decision.
- Confirm the footprint, compacted sub-base depth, and the actual base material or grade being specified.
- Check whether soft spots, edge thickening, or level corrections change the neat rectangular volume.
- Compare bulk bags, loose tonnes, and whether membrane or bedding layers still need separate quantity checks.
If you want to pressure-test the maths
Open the paired measurement guide when you want to check the core area, volume, or run before you change the buying decision.
Sub-Base Calculator by Volume
Work out sub-base volume for patios, paths, and driveways before you order tonnes, bulk bags, or loose aggregate.
Next step links
Open the full Aggregate and Base Estimating project hub or go straight to the Sub-Base Calculator.
Ready to turn this guide into a quote request?
Once you understand the assumptions and buying choices, send builders or merchants the same measured scope so the prices are easier to compare fairly.
- Confirm what the quote should include: materials only, labour only, or both.
- State access, finish level, timing, and any unknowns clearly.
- Ask each supplier or installer to price the same scope and exclusions.
You can also open the wider Aggregate and Base Estimating project hub if the quote depends on more than one material.
How should I use Sub-Base Quantity Guide?
Use it with the Sub-Base Calculator to pressure-test the compacted build-up, density, and merchant delivery route before you order.
What usually changes the Sub-Base Quantity Guide answer most?
Compacted depth, density, formation corrections, and whether the supplier prices by bulk bag or loose tonne usually move the result most.
Should I round up the result?
Usually yes. Weak spots, edge thickening, and delivery minimums can justify a modest spare rather than landing exactly on the theoretical total.