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May 12, 2026
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Project Hub
Drainage Estimating
Drainage work usually needs more than one material at once. You may need pipe length, bedding material, gravel surround, and membrane coverage, so this hub is designed to help you move through those linked trench decisions without missing a part of the order.
Drainage5 calculatorsGuides and quote prep included
How to use it
Planning before buying
Use this project hub for a planning check, then confirm the final order or quote against live product data and site conditions.
Why trust it
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Read the calculator methodology and editorial policy for the standards behind these pages.
Plan the trench build-up in the order you buy it
Drainage work usually needs more than one material at once. You may need pipe length, bedding material, gravel surround, and membrane coverage, so this hub is designed to help you move through those linked trench decisions without missing a part of the order.
Pipe Bedding Calculator
Estimate pipe bedding volume, tonnes, and bulk-bag buying quantities for drainage trenches before you order sand or gravel.
Drainage Pipe Calculator
Estimate drainage pipe lengths, stock pieces, waste allowance, and practical buying totals for trench runs before you order fittings and chambers.
French Drain Gravel Calculator
Estimate french drain gravel volume, tonnes, bulk bags, and practical trench-fill buying totals before you order aggregate for the run.
Geotextile Membrane Calculator
Estimate geotextile membrane rolls, overlaps, and covered area for driveways, french drains, trenches, and separating aggregate layers.
Best route through a drainage trench brief
Use the hub like a trench checklist so pipe, bedding, surround, and membrane all make it into the same supplier or installer request.
1. Measure the trench route first
Start with the full run, likely chamber points, widened sections, and the pipe length so the rest of the trench materials have the right baseline.
2. Split the trench into buying layers
Estimate pipe bedding, gravel surround, and membrane separately rather than letting one bulk-material total hide what each layer actually needs.
3. Send one joined-up drainage request
Package the trench layers, fittings, and access notes together so the supplier or installer is pricing one drainage build-up rather than several disconnected numbers.
More calculators in this hub
Use these related pages when the same project includes extra materials, linked layers, or a different buying format.
Ducting Calculator
Estimate ducting lengths and rough cost for service runs.
Related base-layer calculators
Use these linked tools when the drainage estimate also depends on hardcore, sub-base, or Type 1 below and around the trench build-up.
Hardcore Calculator
Estimate hardcore volume, tonnes, and bulk-bag buying quantities for driveways, patio bases, shed bases, and general fill work.
Sub-Base Calculator
Estimate sub-base volume, tonnes, and delivered quantity for paving, patios, paths, and driveway foundations before you order.
MOT Type 1 Calculator
Estimate MOT Type 1 volume, tonnage, bulk-bag buying quantities, and rough delivery needs for driveways, paths, and compacted sub-base layers.
What changes drainage quantities most
Trench width, bedding depth, gravel surround, fittings, and the total run length usually matter more than the pipe diameter alone.
Where people under-order
Pipe runs are often estimated without enough bedding, gravel surround, or spare pipe, especially where trench width grows around chambers, corners, and outlet points.
Before you order
Check whether fittings, chambers, connectors, membrane overlaps, and the base layers around the trench need to be costed separately from the core trench materials.
Common drainage quantity checks
Use these pages to estimate the main trench materials before you compare pipe sizes, fittings, outlets, and supplier pack options.
Drainage Pipe Length Calculator
Work out drainage pipe lengths from trench run, stock size, and a realistic allowance for bends, cuts, and spare pipe.
Drainage Pipe Buying Guide
Work out how much drainage pipe you need, then sense-check stock lengths, fittings, chambers, and spare allowance.
Ducting Length Calculator
Work out how much Ducting you need from total run length, stock size, and a practical cut allowance.
Ducting Buying Guide
Turn the measured run into a sensible order for Ducting before you buy stock lengths.
Geotextile Membrane Calculator by Area
Work out geotextile membrane rolls from covered area, effective roll coverage, and practical overlap waste.
Geotextile Membrane Buying Guide
Work out how much geotextile membrane you need, then sense-check overlaps, roll coverage, and groundwork use cases.
French Drain Gravel Calculator by Volume
Work out french drain gravel volume from trench length, width, depth, and realistic trench overage before you order.
French Drain Gravel Quantity Guide
Work out how much french drain gravel you need, then sense-check trench width, gravel depth, delivery route, and spare allowance.
Pipe Bedding Calculator by Volume
Estimate pipe bedding volume for drainage trenches, including practical depth, tonnes, and bulk-bag thinking.
Pipe Bedding Quantity Guide
Work out how much pipe bedding you need for a drainage trench, then sense-check tonnes, bulk bags, and surround assumptions.
Best pages to include in a drainage quote request
These are the pages most worth attaching when you want one cleaner trench brief instead of separate notes for pipe, bedding, and surround.
Pipe Bedding Calculator
Calculator: Estimate pipe bedding volume, tonnes, and bulk-bag buying quantities for drainage trenches before you order sand or gravel.
Drainage Pipe Calculator
Calculator: Estimate drainage pipe lengths, stock pieces, waste allowance, and practical buying totals for trench runs before you order fittings and chambers.
French Drain Gravel Calculator
Calculator: Estimate french drain gravel volume, tonnes, bulk bags, and practical trench-fill buying totals before you order aggregate for the run.
Geotextile Membrane Calculator
Calculator: Estimate geotextile membrane rolls, overlaps, and covered area for driveways, french drains, trenches, and separating aggregate layers.
Pipe Bedding Quantity Guide
Guide: Work out how much pipe bedding you need for a drainage trench, then sense-check tonnes, bulk bags, and surround assumptions.
Drainage Pipe Buying Guide
Guide: Work out how much drainage pipe you need, then sense-check stock lengths, fittings, chambers, and spare allowance.
French Drain Gravel Quantity Guide
Guide: Work out how much french drain gravel you need, then sense-check trench width, gravel depth, delivery route, and spare allowance.
Turn the trench estimate into one cleaner drainage brief
Send one request that covers the trench route, the pipe run, and the supporting bedding, surround, and membrane layers so the reply is easier to compare and harder to misread.
- State the trench run, pipe diameter, stock length, and whether fittings, chambers, or branch connections should be included.
- Separate bedding, gravel surround, membrane coverage, and any linked base layer so the quote does not bury missing trench materials inside one vague aggregate line.
- Flag access, delivery limits, outlet details, and whether you want loose tonnes, bulk bags, or merchant stock lengths priced side by side.
You can also open the wider Drainage Estimating project hub if the quote depends on more than one material.