Rebar Calculator

ACI 318 Table 20.5.1.3.1 gives the minimum cover for the exposure; 3 in is the value for concrete cast against ground.
From the drawing or an ACI 318 Ch. 25 calculation - it is not a fixed number. Leave at 0 for no splices.
Used with the lap length to work out how many splices each run needs. Leave at 0 to ignore splicing.
Total bars
40
Rebar Calculator
Bars running the length
20
Bars running the width
20
Total bar length
780.00 ft
Total bar length
237.74 m
Total weight
521.0 lb
Total weight
236.3 kg
Nominal bar diameter
0.500 in
Nominal bar area
0.200 in2
Weight of the bar
0.668 lb/ft
Steel area per foot of slab width
0.2000 in2/ft
Lap splices in each run
0
Cost of the steel
0.00 USD
Intersections to tie
400
Worked out from ASTM A615/A615M, Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement, Table 1 (nominal diameter, area and mass) and 2 other sources.
Bar counts assume bars run the full clear dimension in one piece unless a stock length and lap were given. Corner bars, dowels, chairs, bolsters and tie wire are not included.
This is a quantity take-off, not a reinforcement design. Bar size, spacing, cover, lap length and where the steel sits in the section must come from a design by a licensed engineer working to ACI 318 (or the code adopted where you build). Nothing here checks whether the reinforcement you entered is adequate.

How this is worked out

5 steps
  1. Clear dimensions: 19.5 x 19.5 ft after 3 in of cover at each edge.
  2. Bars running the length: floor(234 / 12) + 1 = 20 per mat, x 1 mat(s) = 20.
  3. Bars running the width: floor(234 / 12) + 1 = 20 per mat, x 1 mat(s) = 20.
  4. Total length = 780 ft; at 0.994 kg/m that is 236.3 kg (521 lb).
  5. Steel area provided: 0.2 sq in per bar at 12 in o.c. = 0.2 sq in per foot of width.

Results are general information, not financial, tax, legal, medical or engineering advice.