This article covers Concrete Planning on Mobile, with practical UK guidance, examples and key points to consider before planning or ordering materials.
How to Use This Concrete Guide
This free mobile concrete guide helps UK tradespeople, self-builders, and groundwork contractors accurately estimate concrete volumes on site — before calling a supplier for a quote. All working follow standard UK ready mix ordering conventions.
Choose the Pour Type
Choose from Slab, Strip Foundation, Pad Foundation, Column, Steps, or Circular Base for the project shape you are planning.
Measure the Dimensions
Use your measured dimensions in millimetres (mm) or metres (m) in millimetres or metres. Include quantity if pouring multiple identical elements.
Choose Grade & Waste
Select the BS 8500 concrete grade for your application and a wastage factor — 10% standard, 15% for complex or remote pours.
Get Your Volume
Your result shows net volume, volume with waste, mix materials breakdown, and an estimated cost range for UK ready mix pricing in 2026.
Round Up to 0.25m³
Always round your final order up to the nearest 0.25m³ increment — running short mid-pour is costly and structurally problematic.
Get Three Quotes
Take your determined volume to at least three suppliers from our National Concrete Suppliers Directory before placing your order.
working method
All volumes are determined using standard geometric formulas: Length × Width × Depth for rectangular elements; π × r² × Depth for circular elements; and a stepped triangular prism formula for stairs. Net volume is multiplied by your chosen wastage factor. Results are rounded to the nearest 0.01m³.
BS 8500 Concrete Grade Guide — UK 2026
Always specify concrete by BS 8500 designated mix, not by C-value alone. The designated mix ensures correct strength, durability, cement content, water-cement ratio, and aggregate size for your specific exposure class and application.
- Grade: C10; BS 8500 Mix: GEN1; Strength: 10 N/mm²; Typical Application: Blinding, lean mix, non-structural fill; Key Note: Non-structural only
- Grade: C15; BS 8500 Mix: GEN2; Strength: 15 N/mm²; Typical Application: Trench fill foundations — normal ground; Key Note: Domestic structural
- Grade: C20; BS 8500 Mix: GEN3; Strength: 20 N/mm²; Typical Application: Domestic strip & pad foundations, normal ground; Key Note: Standard domestic
- Grade: C25 PAV1; BS 8500 Mix: PAV1; Strength: 25 N/mm²; Typical Application: External paving, driveways (cars), patios, steps; Key Note: Air-entrained
- Grade: C25 RC; BS 8500 Mix: RC25/30; Strength: 25 N/mm²; Typical Application: Internal floor slabs, general RC structures; Key Note: Standard structural
- Grade: C30 PAV2; BS 8500 Mix: PAV2; Strength: 30 N/mm²; Typical Application: HGV driveways, industrial yards, bus standings; Key Note: Heavy duty paving
- Grade: C35; BS 8500 Mix: RC35/45; Strength: 35 N/mm²; Typical Application: Structural beams/columns, coastal/contaminated ground; Key Note: Engineer required
- Grade: C40; BS 8500 Mix: RC40/50; Strength: 40 N/mm²; Typical Application: High load columns, post-tensioned, precast; Key Note: Engineer required
Always Confirm Grade in Writing
When ordering ready mix concrete, always confirm your BS 8500 designated mix grade in writing with your supplier before the pour. A verbal order for “C25” may result in a non-air-entrained mix being delivered when PAV1 (air-entrained C25) was required for an external driveway. Written confirmation protects both parties.
Ready to Order? Use Our National Concrete Suppliers Directory
Once you have your determined volume, visit our National Concrete Suppliers Directory 2026 to find Hanson, Tarmac, CEMEX, Aggregate Industries, Breedon, and local volumetric operators near you. Always get at least three quotes before placing your order.
On-Site Ordering Tips — UK 2026
Using the working method correctly before calling a supplier can save significant money and time. Here are the key rules experienced UK groundwork contractors follow on every pour.
Volume Working Rules
- Always round UP:Round your final order up to the nearest 0.25m³ — never round down. Running short mid-pour is catastrophically expensive
- Add 10% minimum waste:For flat slabs in controlled conditions; 15% for complex shapes, steps, and raking pours; 20% for remote or difficult access sites
- Deduct openings only if large:Ignore openings under 0.1m² in slabs — the effort and risk of under-ordering outweighs the saving
- Multiple elements:Work out each element separately then sum them — never attempt a combined shorthand estimate for foundations + slab in one working
Short Load & Minimum Order Rules
- Under 1m³:Use a volumetric concrete supplier — short load fees from a drum mixer (£120–£280) are almost never worth it on orders under 1m³
- 1–3m³:Consider volumetric vs. drum mixer with short load — get quotes for both and compare total delivered cost
- Over 3m³:Ready mix drum truck is almost always the most economical option — single load, fastest delivery
- Very small repairs (under 0.2m³):Use 25kg or 20kg bagged concrete — Rapid Set or Postcrete for post holes, Fastcast for structural repairs
Site Preparation Before Delivery
- Access width:Confirm minimum 3m clear width for mixer trucks, 3.5m for larger boom-mounted drums
- Access height:Minimum 4m clearance on all approach routes — check bridges, overhead cables, and canopies
- Ground bearing:Mixer trucks fully loaded weigh 26–32 tonnes — confirm your drive, path, or verge can bear the load
- Pump readiness:If using a concrete pump, have it positioned and primed before the first drum arrives
- Labour ready:Have all finishing labour on site and ready before the truck arrives — concrete waits for nobody
- Formwork check:Inspect all formwork immediately before the pour — a failed shutter during pouring is a major hazard and cost
The Golden Rule — Confirm Everything in Writing
Before every concrete pour: confirm mix grade, volume in m³, delivery date and time window, site address, access details, and price per m³ — all in writing by email or WhatsApp. This single habit prevents the majority of disputes between contractors and concrete suppliers.
Concrete Guide — Frequently Asked Questions
Common questions about working out concrete volumes and ordering ready mix in the UK in 2026.
- Formula:Volume (m³) = Length (m) × Width (m) × Depth (m)
- Example:A 5m × 4m slab at 150mm thick = 5 × 4 × 0.150 = 3.0m³ net
- Add waste:3.0 × 1.10 (10% waste) = 3.3m³
- Round up:Round 3.3 up to 3.5m³ (nearest 0.25m³) for your order
- Minimum depth:Internal domestic slabs — 100mm minimum; garage floor — 125mm minimum; driveways — 150mm minimum
- Grade for slabs:Internal slab — RC25/30 (C25); external driveway — PAV1 (air-entrained C25); HGV driveway — PAV2 (C30)
- Strip foundation minimum depth:750mm to underside on sand, gravel, and chalk soils
- Clay soils (most of UK):900mm minimum — 1000mm+ strongly recommended due to shrink/swell movement
- Trees nearby on clay:1.5m–2.5m+ depth may be required — structural engineer must work out
- Made ground or contaminated ground:Piled foundations may be required — structural engineer required
- Strip foundation minimum width:600mm for a single-storey wall; 750mm for two-storey — structural engineer to confirm for any load-bearing wall
- Foundation concrete grade:GEN3 (C20) minimum for normal ground; RC35 with SRPC or GGBS for sulphate-bearing ground
- Scotland:Scottish Building Standards equivalent — consult your local authority verifier before designing foundations
- Coverage per 25kg bag:approximately 0.012m³ when mixed to standard consistency
- Coverage per 20kg bag:approximately 0.009m³
- Bags needed formula:Divide your net volume (m³) by 0.012 for 25kg bags — then add 10% waste
- Fence post (1 post):Approximately 2–3 × 25kg bags per post (Postcrete / fast-setting preferred)
- 1m³ equivalent:84 × 25kg bags — at this volume, a volumetric supplier is almost always cheaper and faster
- Break-even:For volumes over 0.5m³, a volumetric concrete truck delivery is typically more cost-effective than bags including mixing labour
- Formwork imprecision:Even accurately built shuttering has small dimensional variations — actual volume is always slightly larger than determined
- Ground irregularity:Subgrades are never perfectly flat — extra concrete fills low points below the design level
- Drum residuals:A small amount remains in the mixing drum and chutes — typically 0.02–0.05m³ per load
- Spillage:Especially on awkward pours, difficult access, or pump-assisted delivery
- Sample cubes:Structural pours require test cube samples taken at the point of discharge
- Running short mid-pour:The most expensive scenario — a cold joint in structural concrete causes a defect requiring cut-out and re-pour
- Method:Each step is determined as a rectangular block. The first step (from the bottom) = Width × Tread × (Total Height). The second step = Width × Tread × (Total Height minus 1 riser). Continue for each step upward
- Simplified formula:Total Volume = Width × Tread Depth × Riser Height × (n × (n+1) / 2) — where n = number of steps
- Waste factor:Use 15% minimum for steps — the stepped profile creates more formwork complexity and spillage risk than a flat slab
- Grade:Exterior steps — PAV1 (air-entrained C25) minimum for freeze-thaw resistance; C30 for exposed coastal locations
- Our guide:The Steps section above handles all this automatically — just enter step width, tread depth, riser height, and quantity
- Garden path (pedestrian only):PAV1 (C25, air-entrained) — 100mm minimum depth
- Driveway — cars only:PAV1 (C25, air-entrained) — 150mm minimum depth on compacted sub-base
- Driveway — vans, light commercial:PAV2 (C30, air-entrained) — 150–200mm minimum depth
- Driveway — HGVs, lorries:PAV2 (C30) — 200–250mm depth on 150mm compacted Type 1 sub-base minimum
- Patio / terrace:PAV1 (C25, air-entrained) — 100mm minimum; 125mm recommended for longevity
- Why air-entrained (PAV designation)?The air-entraining admixture creates micro-bubbles that accommodate ice crystal expansion, preventing surface scaling in freeze-thaw cycles — critical for all UK external paving
- Works offline:Once the page has loaded in your browser, all six guides work entirely in your browser without any server connection — so they work in areas with no signal
- Save to home screen:On iPhone: tap Share → Add to Home Screen. On Android: tap the browser menu → Add to Home Screen. This creates an app-like shortcut
- No account needed:There is no login, registration, or app download required — 100% free and anonymous
- Mobile optimised:All measurements are finger-friendly with large tap targets — designed for use in muddy gloves on a building site
- Print results:Use your browser’s Print function to print or save a PDF of your determined result for site records or quotes
- Ready mix pricing:Based on indicative UK regional ready mix prices for 2026 — C25 ranges from approximately £62/m³ (Midlands/North) to £115/m³ (Central London)
- Volumetric pricing:Typically 10–20% higher per m³ than equivalent drum-mixer ready mix, but with no short-load fee and no minimum order
- Bagged concrete pricing:Based on 25kg bags at approximately £5.50–£7.50 per bag from UK builders merchants in 2026
- What’s not included:Delivery charge (typically free within 10 miles, £2–£5/m³ per mile beyond), concrete pump hire (£180–£600), short load fees, ULEZ surcharges in London, and out-of-hours premiums
- Purpose:The cost estimate helps you understand budget magnitude — always get actual written quotes before committing to your project budget
Related UK Construction Resources & Directories 2026
Free companion resources and supplier directories to use alongside this concrete guide on site and in the office.
Guide Disclaimer — Always Verify Before Ordering
This guide provides indicative estimates only. Always verify determined volumes on-site before ordering. For structural concrete pours on commercial or public buildings, engage a qualified structural engineer to specify mix design, volume, and pour sequence. TheConcrete Centreprovides free BS 8500 specification guides for all common UK applications.
For additional concrete quantity and estimating resources, you can also visit ConcreteCalcs.com.