Rebar Weight Calculator (kg & Tonnes) – UK & Ireland
This rebar weight calculator is designed for UK and Ireland construction jobs including house extensions, RC frames and civil works such as foundations, slabs and retaining walls.
It helps you convert bar schedules and cutting lists into accurate kg and tonne totals so you can:
Order steel correctly
Check supplier weights
Plan lifts and deliveries
Based on standard UK & Ireland D²/162 formula
Calculate your rebar weight in seconds
🧠 How rebar weight is calculated
To calculate rebar weight, you need the following:"
Bar diameter (e.g. T10, T12, T16)
Length of each bar (including laps and bends)
Number of bars
📏 Quick example
Example – T16 foundation bars (UK strip foundation)
Diameter: 16mm
Weight per metre: 1.58 kg/m
Length: 24m
Quantity: 3
👉 Total weight = 113.8 kg (0.11 tonnes)
🏗️ Where this is used
House extension foundations
RC frame slabs, beams and columns
Retaining walls and civil structures
⚠️ Common mistakes
1. Missing laps and bends
Not including lap lengths or hooks will understate weight.
2. Mixing bar sizes
Small changes (T12 → T16) can significantly affect weight.
3. Wrong units
Always use metres (not mm or ft)
4. No allowance for waste
Allow 5–10% extra for offcuts and site adjustments.
📊 Typical bar sizes
Common rebar sizes in the UK & Ireland:
T10
T12
T16
T20
T25
T32
👉Larger bars are significantly heavier due to the squared formula (D²).
❓ FAQs
How do I calculate rebar weight for a concrete slab?
Multiply total bar length by kg/m for each bar size, then sum.
Can I use this for civils and RC frames?
Yes — same formula applies to all reinforced concrete jobs.
How do I check supplier weights?
Compare your calculated tonnes against delivery notes.
Do I need shape codes?
No — the calculator only needs total bar length. Shape codes are only required when generating cutting lists.
Weight per metre (kg/m) = D² / 162
The standard formula used is:
Total weight = kg/m × length × quantity
Then:
Or use our rebar calculator to get your totals instantly.
You can calculate similar values instantly using our rebar calculator
Ready to calculate your rebar weight in seconds?