MixDesignCalc Complete IS 10262:2019 Guide 2026 — All 5 Steps Explained with Worked Examples. Figure 1 (W/C Curves), Table 2 (Water Content), Table 1 (Standard Deviation), Annex A (FA%). IS 456:2000 Interaction. Full Interactive IS 10262 Calculator for M20–M60.
Run IS 10262 DesignIS 10262:2019 "Concrete Mix Proportioning — Guidelines (Second Revision)" is the Bureau of Indian Standards document that governs concrete mix design in India. It is the mandatory reference for all design mix concrete under IS 456:2000 and supersedes IS 10262:2009 (First Revision) and the original IS 10262:1982. Understanding IS 10262:2019 is foundational to using MixDesignCalc and to any engineering work involving concrete proportioning in India.
Click each step to expand the full explanation, key formulas, table references, and design decisions.
The target mean compressive strength (f'cr) is the mean strength a mix must actually achieve so that the probability of any individual test result falling below fck (characteristic strength) is no more than 5%. It is always higher than fck.
Important: For a new mix design without production history, IS 10262:2019 Clause 4.2 allows using S from Table 1. Once 30+ results are available, compute actual SD and update the mix design annually or when the SD changes by more than 0.5 MPa.
The free water-cement ratio is determined from two sources simultaneously — strength (IS 10262 Figure 1) and durability (IS 456:2000 Table 5). The lower of the two is adopted.
The Figure 1 curves were developed from tests on Indian cements. Since cement quality has improved between 2009 and 2019, the curves were slightly revised in IS 10262:2019. For practical use, the curves are available digitised in MixDesignCalc — you never need to read the chart graphically.
The free water content is the mass of water per cubic metre of concrete, not counting water absorbed by aggregates (aggregates are on SSD basis in IS 10262). It is determined from IS 10262:2019 Table 2 based on slump, maximum aggregate size, and aggregate type, with corrections for M-Sand and admixtures.
Cement content follows directly from the adopted W/C and the selected free water:
Step 5 is the absolute volume method — the fundamental identity that the volumes of all ingredients must sum to exactly 1.000 m³:
Complete IS 10262:2019 procedure — all five steps with IS 456:2000 durability checks, SCM support, SP correction, M-Sand correction, FM correction, and full volume balance. Use this for any grade M20 to M60.
| Ingredient | Mass (kg/m³) | SG | Volume (m³) | % Total |
|---|
| Control Level | Standard Deviation S (MPa) | When Applicable | f'cr Increase (M30) |
|---|---|---|---|
| Excellent | ≤ 2.5 | Specialist precast, highly controlled RMC; rare in India | +4.1 MPa |
| Very Good M40+ Mandatory | ≤ 3.5 | Well-run RMC plant with QC; required for M40+ | +5.8 MPa |
| Good Standard | ≤ 4.0 | Typical RMC plant; default for new mix without history | +6.6 MPa |
| Fair | ≤ 5.0 | Variable production; on-site batching with limited QC | +8.3 MPa |
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| Max Agg Size | Type | Slump 25–50mm | Slump 75–100mm Standard | Slump 150–175mm | Correction — M-Sand | Correction — SF per 1% |
|---|---|---|---|---|---|---|
| 10 mm | Crushed | 208 | 228 | 250 | +7 kg/m³ | +2 kg/m³ |
| Rounded | 180 | 200 | 220 | |||
| 20 mm Standard | Crushed | 186 | 204 | 222 | ||
| Rounded | 160 | 180 | 195 | |||
| 40 mm | Crushed | 165 | 182 | 199 | ||
| Rounded | 145 | 160 | 175 |
| W/C Ratio | Zone I (Coarse) | Zone II Preferred | Zone III | Zone IV (Fine) | Notes |
|---|---|---|---|---|---|
| 0.35 | 36–40% | 30–34% | 26–30% | 22–26% | Lower FA% at low w/c |
| 0.40 | 38–42% | 32–36% | 28–32% | 24–28% | |
| 0.45 | 40–44% | 34–38% | 30–34% | 26–30% | |
| 0.50 Common | 42–46% | 36–40% | 32–36% | 28–32% | Use midpoint of range |
| 0.55 | 44–48% | 38–42% | 34–38% | 30–34% | |
| 0.60+ | 46–50% | 40–44% | 36–40% | 32–36% | High w/c — PCC grade |
Q: Is IS 10262:2019 mandatory or can I use IS 10262:2009?
IS 10262:2019 supersedes IS 10262:2009, which in turn superseded IS 10262:1982. In regulatory terms, the latest published IS standard takes precedence. For projects under IS 456:2000 (all Indian RCC construction), the current reference is IS 10262:2019. In practice, many NABL laboratories and engineers still follow IS 10262:2009 procedures — the results differ slightly (primarily in SCM guidance, M-Sand correction, and SD table clarity) but are broadly comparable for grades M20–M40 with OPC and no SCM. For any formal mix design report submitted to a government agency (CPWD, PWD, Railways, NHAI), specify IS 10262:2019 explicitly and ensure the laboratory report cites the 2019 edition.
Q: How do I read IS 10262 Figure 1 (W/C vs strength curve)?
IS 10262:2019 Figure 1 is a chart with W/C ratio on the X-axis (0.20 to 0.80) and compressive strength on the Y-axis (10 to 70 MPa). There are separate curves for OPC 53, OPC 43, PPC, and PSC cement types. To use it: (1) Compute f'cr from Step 1; (2) Find f'cr on the Y-axis; (3) Read horizontally to the correct cement type curve; (4) Drop vertically to the X-axis to read W/C. This read is digitised in MixDesignCalc — you input cement type and f'cr and get the W/C directly from the same mathematical relationships that underlie the chart. Note that the chart represents mean expected behaviour — actual performance varies with cement source, so trial mix verification is mandatory.
Q: What is the IS 10262 Annex A FM correction rule and when does it apply?
IS 10262:2019 Annex A provides FA% values in Table A-1 for specific FM values (typically the midpoint of each zone). When your actual FA has a different FM from the design FM: for every 0.1 increase in FM from the design FM, increase FA% by 1.5%; for every 0.1 decrease, reduce FA% by 1.5%. This correction applies whenever the actual FM of the sand differs by more than 0.2 from the design FM. It is mandatory to apply if sand is sourced from a different quarry lot with a different FM. Example: design FM = 2.70 (Zone II midpoint), actual FM = 2.90 → ΔFA% = (2.90−2.70)/0.1 × 1.5% = +3%. If designed FA% was 36%, adjusted FA% = 39%.
Q: Can the IS 10262 procedure be used for SCM blends like OPC + fly ash?
Yes — IS 10262:2019 Annexes A, B, and C specifically address fly ash, GGBS, and silica fume respectively. For OPC + fly ash: the cement content calculation gives total binder; fly ash replaces a portion of OPC (IS 1489 PPC already has FA blended, but when adding FA separately to OPC 53: FA = 15–35% of total binder). The k-value method in IS 10262:2019 Annex B provides an "effective w/c" for fly ash and GGBS — k_FA = 0.4–0.5; k_GGBS = 0.8–1.0 — allowing the effective binder contribution to be calculated. For silica fume (Annex C): apply the +2 kg/m³ water correction per 1% SF, and compute OPC fraction separately from the SF fraction as shown in the IS 10262:2019 HPC examples.