Rebar Weight Table – kg/m, lb/ft, Bar Sizes & Stock Weights
Reference linear weights for common metric reinforcing-bar diameters and US rebar sizes, with quick stock-length weights and practical methods for converting a reinforcement takeoff from metres or feet into kilograms, pounds and tonnes.
Metric rebar weight per metre
The values below are useful for preliminary takeoff and checking. The cross-sectional area is based on the nominal diameter, and the linear mass is approximately consistent with ordinary reinforcing steel density. Product standards, rolling tolerances and manufacturer declarations can produce small differences, so use the actual product data when purchasing accuracy matters.
| Nominal diameter | Approx. area mm² | Approx. weight kg/m | 6 m bar | 12 m bar |
|---|---|---|---|---|
| 6 mm | 28.3 | 0.222 | 1.33 kg | 2.66 kg |
| 8 mm | 50.3 | 0.395 | 2.37 kg | 4.74 kg |
| 10 mm | 78.5 | 0.617 | 3.70 kg | 7.40 kg |
| 12 mm | 113.1 | 0.888 | 5.33 kg | 10.66 kg |
| 14 mm | 153.9 | 1.210 | 7.26 kg | 14.52 kg |
| 16 mm | 201.1 | 1.580 | 9.48 kg | 18.96 kg |
| 20 mm | 314.2 | 2.470 | 14.82 kg | 29.64 kg |
| 25 mm | 490.9 | 3.850 | 23.10 kg | 46.20 kg |
| 28 mm | 615.8 | 4.830 | 28.98 kg | 57.96 kg |
| 32 mm | 804.2 | 6.310 | 37.86 kg | 75.72 kg |
Planning values, rounded for quick takeoff. The available diameter series and nominal mass can differ by market and product specification.
US rebar weight per linear foot
US bar-size numbers are standardized designations rather than a request to measure the ribbed outside diameter with a tape. The nominal diameter represents a plain round bar with the same weight per linear foot. The `lb/ft` values below match common published straight-rebar data for #3 through #11.
| Bar size | Nominal diameter | Weight lb/ft | Approx. kg/m | 20 ft bar |
|---|---|---|---|---|
| #3 | 0.375 in | 0.376 | 0.560 | 7.52 lb |
| #4 | 0.500 in | 0.668 | 0.994 | 13.36 lb |
| #5 | 0.625 in | 1.043 | 1.552 | 20.86 lb |
| #6 | 0.750 in | 1.502 | 2.235 | 30.04 lb |
| #7 | 0.875 in | 2.044 | 3.042 | 40.88 lb |
| #8 | 1.000 in | 2.670 | 3.973 | 53.40 lb |
| #9 | 1.128 in | 3.400 | 5.060 | 68.00 lb |
| #10 | 1.270 in | 4.303 | 6.404 | 86.06 lb |
| #11 | 1.410 in | 5.313 | 7.907 | 106.26 lb |
For procurement, confirm the exact bar designation, grade, available stock length and published linear weight with the supplier or fabricator. Do not assume a metric diameter is a direct one-to-one replacement for a US bar number.
How to calculate rebar weight from total length
Example: a takeoff contains 268 m of Ø12 reinforcement. Using 0.888 kg/m gives approximately 238 kg. If the takeoff later increases to 295 m because laps, hooks or additional bars are added by the reinforcement schedule, the mass must be recalculated from the updated length.
For large projects, divide kilograms by 1,000 to express metric tonnes. In US units, 2,000 lb equals one short ton. Keep the original detailed quantity as well as the rounded purchasing or transport quantity so the reason for any difference remains visible.
Important: total bar length should come from a reinforcement takeoff or schedule. Weight conversion does not create missing lap lengths, anchorage, hooks, chairs, dowels or local reinforcement automatically.
Diameter-squared effect: why a slightly larger bar becomes much heavier
Rebar mass per metre increases approximately with the square of its diameter. This means doubling the diameter makes the theoretical linear mass about four times greater, not twice as great.
| Metric size | Approx. kg/m | Weight versus Ø10 | 100 m of bar | Takeoff implication |
|---|---|---|---|---|
| Ø10 | 0.617 | 1.00× | 61.7 kg | Baseline comparison. |
| Ø12 | 0.888 | 1.44× | 88.8 kg | 20% more diameter produces about 44% more mass per metre. |
| Ø16 | 1.580 | 2.56× | 158.0 kg | A moderate size change can strongly affect tonnage and handling. |
| Ø20 | 2.470 | 4.00× | 247.0 kg | Twice the diameter is approximately four times the linear mass. |
This section explains sensitivity only. It is not a reason to substitute one bar size for another: reinforcement size and spacing are structural design decisions.
Quick theoretical formula for metric bars
For a nominal round cross-section and ordinary steel density, a convenient estimating shortcut is:
For Ø12: 12² ÷ 162 ≈ 0.889 kg/m, close to the rounded 0.888 kg/m table value. For Ø20: 20² ÷ 162 ≈ 2.47 kg/m.
The shortcut is useful for checking a takeoff, but a published product mass is better when the actual reinforcing bar is known.
Why ribs do not mean “measure the outside and use πd²/4”
Deformed reinforcing bars have ribs designed for bond with concrete. The nominal diameter or standardized bar designation is therefore the correct basis for a weight table, not an improvised measurement over the ribs with calipers or a tape.
For US bars, the nominal diameter is specifically related to the weight-equivalent plain round bar. For metric products, use the designation and nominal mass stated by the applicable product documentation.
When checking delivered steel, compare tags, mill documentation and supplier data rather than trying to reverse-engineer mass from an outside rib dimension.
From one bar to project tonnage: a practical workflow
- Read the design input. Identify bar size, spacing, layers, zones, laps, hooks and special reinforcement from the project documents.
- Calculate or schedule the total length. Keep different bar sizes separate. A single combined metre total is not useful if it contains Ø10, Ø12 and Ø16 together.
- Multiply each size by its unit weight. Convert metres to kilograms or feet to pounds separately for each bar size.
- Add the masses. This gives a theoretical takeoff mass for the reinforcement included in the schedule.
- Separate fabrication/purchasing effects. Stock lengths, cutting, couplers, laps, fabrication waste and bundle quantities may change the ordered amount.
- Check supplier data. Confirm the exact product, grade and delivered mass basis before using the result for a purchase order, crane lift or vehicle payload.
Worked example: slab grid weight
Assume a reinforcement takeoff has already calculated 269.28 m of Ø12 bar, including the project's chosen length allowance. The table gives approximately 0.888 kg/m.
If the same total length were Ø16 instead, the approximate mass would be:
This illustrates why bar size has a large effect on handling and tonnage. It does not imply that Ø12 and Ø16 are interchangeable. The structural schedule decides which size is required.
Use the Rebar Calculator when you need to estimate a simple rectangular slab grid from dimensions and spacing, then use this table to verify the linear-weight conversion.
Does your rebar weight result look realistic?
- If increasing bar diameter appears to increase total weight only slightly, check whether the correct unit weight was selected.
- If the mass is thousands of kilograms for a very small slab, check whether millimetres, metres, inches or feet were mixed in the length takeoff.
- If the number of stock bars looks reasonable but total mass does not, confirm whether weight was calculated from used length or from purchased stock length. Those are different questions.
- If a bar schedule contains several diameters, calculate each diameter separately before adding the masses.
- If the result controls lifting or transport, use the supplier/fabricator's actual bundle and product information rather than a generic approximate table.
Common rebar weight-table mistakes
| Mistake | Why it causes trouble | Better approach |
|---|---|---|
| Using one unit weight for mixed bar sizes | Larger diameters are disproportionately heavier. | Keep separate length totals for every diameter or bar designation. |
| Treating #4 as exactly 4/8 in outside diameter everywhere | US designations use nominal dimensions and standardized weights; ribs are not the measurement basis. | Use the published bar-size table. |
| Forgetting laps, hooks or extra reinforcement | The weight conversion can be correct while the input length is incomplete. | Take length from the detailed reinforcement schedule. |
| Confusing used length with purchased stock | Cutting and stock-length rounding can increase purchased steel. | Track theoretical installed length and procurement quantity separately. |
| Using approximate weight for a lifting plan | Operational safety needs actual load information and an appropriate safety process. | Use bundle tags, supplier documents and the approved lifting/transport plan. |
For construction students and apprentices
Rebar weight is a useful exercise because it connects geometry, units and structural drawings. First calculate or read the total bar length. Then multiply by the published mass per unit length. The structural design problem and the quantity-conversion problem are separate.
Exercise: a schedule contains 180 m of Ø12 and 95 m of Ø16 reinforcement. Using this table:
Check question: why can you not add 180 m + 95 m first and multiply by one average kg/m value? Because the two diameters have different linear masses, and an arbitrary average can distort the result.
Advanced question: if the ordered stock length is greater than the installed/cut length, which mass belongs in the purchase estimate? The purchased-stock mass. Keep the installed theoretical mass separately so the procurement difference is visible.
Continue from reinforcement length to a checked material takeoff
Use the weight table after the design inputs are known, then continue with the related concrete and takeoff workflow.