#4 rebar weighs 0.668 lb per foot (0.994 kg/m). That’s the exact theoretical unit weight: a 20-ft stick weighs 13.36 lb, a 40-ft stick weighs 26.72 lb, and 100 feet of #4 bar totals 66.8 lb. #4 bar is 1/2 inch (12.7 mm) in nominal diameter.
Need a different length or quantity? The Rebar Weight Calculator gives you the exact weight for any bar size, length, and number of bars.
#4 rebar weight: the direct answer
The weight of #4 rebar comes straight from the standard formula: (bar number ÷ 8)² × 2.67 = (4 ÷ 8)² × 2.67 = (0.5)² × 2.67 = 0.25 × 2.67 = 0.668 lb/ft. In metric: 12.7² ÷ 162.2 = 161.29 ÷ 162.2 = 0.994 kg/m. Both values are theoretical unit weights based on the nominal 1/2-inch diameter.
Here are the weights you’ll actually order and haul:
| Length of #4 bar | Weight (lb) | Weight (kg) |
|---|---|---|
| 1 ft | 0.668 | 0.304 |
| 10 ft | 6.68 | 3.03 |
| 20 ft | 13.36 | 6.06 |
| 40 ft | 26.72 | 12.12 |
| 100 ft | 66.8 | 30.3 |
Verifying the 0.668 lb/ft figure
You don’t have to take the number on faith — it cross-checks three ways. First, the imperial formula: (4 ÷ 8)² × 2.67 = 0.25 × 2.67 = 0.6675, which rounds to 0.668. Second, the metric route: a #4 bar is 12.7 mm in diameter, so 12.7² ÷ 162.2 = 161.29 ÷ 162.2 = 0.994 kg/m, and converting back gives 0.994 ÷ 1.4882 = 0.668 lb/ft — the two systems agree. Third, the tonnage check: 2,000 lb ÷ 0.668 = 2,994 ft per short ton, matching the industry rule of thumb of roughly 3,000 feet of #4 per ton.
These independent checks all land on the same value, which is why 0.668 lb/ft is the standard theoretical weight quoted on mill certs and supplier cut sheets.
Where #4 rebar is commonly used
#4 bar is the workhorse of residential concrete work. You’ll find it specified for slab-on-grade reinforcement, footings, foundation walls, and driveways. It’s light enough to handle by hand — a 20-ft stick at 13.36 lb is a one-person lift — yet heavy enough to provide real tensile strength in low-to-moderate load applications.
That said, bar size and spacing must always come from engineered plans or local building code. This article covers estimating weight, not structural design. Anything load-bearing should be sized by a licensed structural engineer and approved by your local authority having jurisdiction (AHJ).
Key variables that change the answer
Length of stick. Rebar is commonly sold in 20-ft and 40-ft lengths. A 40-ft stick of #4 weighs 26.72 lb — still manageable for two people, but awkward. Cutting and hauling losses depend on the lengths your supplier stocks.
Quantity. Total weight = 0.668 × total feet. A small slab job can easily reach several hundred feet of #4, putting the order in the hundreds of pounds — relevant for vehicle loading and delivery.
Mill tolerance. The 0.668 lb/ft figure is theoretical. Real bars vary slightly with manufacturing tolerance, so expect a percent or two of difference from weighed deliveries. Suppliers quote and sell by theoretical weight, so this is normal.
Common mistakes to avoid
Rounding 0.668 to 0.5. Using 0.67 instead of 0.668 is perfectly fine — the difference is negligible on real orders. But some people mentally round to 0.5 lb/ft (“about half a pound”), which understates the weight by 25% and can throw off a materials budget badly.
Buying by count without checking total weight. “I need 50 sticks” sounds small until you do the math: 50 × 20 ft × 0.668 = 668 lb. Check the total weight before deciding you can haul it in a pickup.
Forgetting lap splices and waste. When bars must overlap to continue a run (lap splices), you need extra length beyond the simple run total. Add roughly 10% for laps and cutting waste when estimating an order.
Is #4 rebar 1/2 inch?
Yes — #4 bar has a nominal diameter of 4/8″, i.e., 1/2 inch (12.7 mm). The bar number always equals the diameter in eighths of an inch.
How many feet of #4 rebar are in a ton?
2,000 lb ÷ 0.668 lb/ft = 2,994 feet per short ton (roughly 3,000 ft). Using metric tonnes: 1,000 kg ÷ 0.994 kg/m = 1,006 metres per tonne.
How much does a bundle of #4 rebar weigh?
Bundles vary by supplier, but a common bundle is fifty 20-ft sticks: 50 × 13.36 lb = 668 lb. Always confirm the stick count and length with your supplier — that’s what determines the bundle weight.
Can I just use 0.67 lb/ft for estimates?
Yes. Rounding 0.668 to 0.67 changes totals by less than half a percent — fine for budgeting and ordering. Just don’t round to 0.5 or 0.7, where the error becomes meaningful at scale.
Get the exact weight for your project with the Rebar Weight Calculator, then read the complete guide and the formula explained walkthrough for the full picture.
