Free tools
Free calculators for materials testing labs
Free calculators for concrete and soils testing, built on the same tested calculation library as ProofGrit. Instant results in the units each test uses, nothing to sign up for.
Concrete
- 01Concrete strength calculatorCylinder strength from two diameters and the maximum load, with L/D correction and the set average.Strength (psi) = max load (lbf) ÷ (π × D² ÷ 4), with D the average of two diameters, corrected when L/D ≤ 1.75.
- 02ACI 318 acceptance calculatorCheck strength tests against both ACI 318 acceptance criteria: running average of three and the single-test limit.Pass when every average of 3 consecutive tests ≥ f'c, and no test is below f'c − 500 psi (f'c ≤ 5,000) or 0.90 × f'c (f'c > 5,000).
- 03Flexural strength calculatorModulus of rupture of a concrete beam from third-point (C78, both fracture cases) or center-point (C293) loading, to the nearest 5 psi.C78 inside the middle third: R = P × L ÷ (b × d²). C78 outside (≤ 5 % of span): R = 3 × P × a ÷ (b × d²). C293: R = 3 × P × L ÷ (2 × b × d²).
- 04Concrete unit weight calculatorFresh concrete density from a filled measure, plus yield, relative yield and gravimetric air content from the batch ticket and mix design.D = (Mc − Mm) ÷ Vm; Y = W ÷ D; relative yield = Y ÷ design volume; A = (T − D) ÷ T × 100.
Soils and aggregates
- 01Proctor curve calculatorWet and dry density per point, a fitted moisture-density curve with zero air voids line, MDD and OMC.Wet density = (net wet mass g ÷ 453.592) ÷ mold volume ft³; dry density = wet ÷ (1 + w/100); ZAV = Gs × 62.4 ÷ (1 + w/100 × Gs).
- 02Nuclear density calculatorDry density, percent compaction, moisture status and the daily standard count check for nuclear gauge tests.Dry density = wet × 100 ÷ (w + 100); % compaction = dry ÷ MDD × 100. Standard counts within 1 % (DS) and 2 % (MS) of the previous 4.
- 03Sand cone calculatorSand in the hole, hole volume, wet and dry density and percent compaction for the sand cone test.Sand in hole = (initial − final) − cone; hole volume = sand in hole ÷ sand density; wet = soil ÷ volume; dry = wet ÷ (1 + w/100).
- 04Sieve analysis calculatorPercent retained, cumulative retained and percent passing for each sieve, a log-scale gradation chart and fineness modulus.% retained = mass retained ÷ total dry mass × 100; cumulative = running sum; % passing = 100 − cumulative; FM = Σ cumulative % on the standard series ÷ 100.
- 05Aggregate specific gravity calculatorBulk specific gravity (OD and SSD), apparent specific gravity and absorption for coarse (C127) or fine (C128) aggregate.C127: bulk OD = A ÷ (B − C), bulk SSD = B ÷ (B − C), apparent = A ÷ (A − C), absorption = (B − A) ÷ A × 100.
- 06CBR calculatorCBR at 0.1 in and 0.2 in penetration from test unit loads, the value to report, and when to repeat the test.CBR = test unit load ÷ standard unit load × 100, with 1,000 psi at 0.1 in and 1,500 psi at 0.2 in.
Soil classification
- 01USCS classification calculatorGroup symbol, basic group name and the decision path from gradation and Atterberg limits, with a plasticity chart.Coarse if more than 50 % is retained on No. 200; Cu = D60 ÷ D10, Cc = D30² ÷ (D10 × D60); A-line PI = 0.73 × (LL − 20).
- 02Atterberg limits calculatorMultipoint liquid limit from a least-squares flow curve, plastic limit from trials, plasticity index or NP, and a plasticity chart.LL = water content at 25 blows on the least-squares line of w vs log10(blows); PL = average of trials; PI = LL − PL, or NP.
- 03Soil moisture content calculatorWater mass, dry soil mass and moisture content from container, wet and dry weighings.w = (container + wet − container + dry) ÷ (container + dry − container) × 100.
Looking for the standard behind a calculator? See the standards index. These calculators show the arithmetic only. Always follow the current standard and your project specifications. Have a question about a calculation? Contact the team.