// INTERACTIVE TOOL
Concrete Strength Predictor
Got 7-day cube results? Predict 28-day strength and flag potential failures early. Save 21 days of guessing.
20 sec
// Live Tool
Inputs
7d/65%
7d/60%
7d/50%
7d/45%
7d/80%
×1
×0.95
×0.85
×0.7
Live Output
Predicted 28-Day Strength
36.5N/mm²
vs design fck = 30 N/mm²122% — PASS
14-Day PredictedGOOD
32.0N/mm²
Roughly 87.5% of 28-day prediction.
56-Day PredictedGOOD
37.3N/mm²
Minimal additional gain after 28-day.
IS 456 AcceptanceGOOD
PASS
Above fck + margin.
// Interpretation
What this means
// DO · Likely PASS
Based on the 7-day cube result, your concrete should pass acceptance at 28-day testing. Continue normal curing protocol.
// NOTE · When to investigate
Even one outlier 7-day result deserves attention. IS 456 requires investigation if an individual sample is >3 N/mm² below characteristic strength. Don't wait for 28-day.
// Context
When to use this
// What is this
Concrete strength gain follows a known curve. By measuring 7-day strength, you can predict 28-day strength with reasonable accuracy. This lets you take corrective action 21 days earlier if there's a problem.
// When to use it
Use immediately after 7-day cube test. If predicted 28-day is below acceptance, investigate now — don't wait 21 more days.
// Next Step
Move from numbers to a pour
// FAQ
Questions, answered
// Related Tools