How to use this calculator
- Enter or choose pour date.
- Enter or choose curing period.
- Enter or choose strike side formwork after.
- Enter or choose remove soffit props after.
- Enter or choose strength test age.
- The curing ends updates as you type. Use Copy result or Share to keep it.
Method
Event date = Pour date + n calendar days
- n
- days after pouring for each event, from your specification
Worked example
- Pour on Monday 2 November 2026.
- Strike sides at +2 days = 4 Nov; curing ends at +7 = 9 Nov; props out at +14 = 16 Nov.
- The 28-day test falls on 30 November.
For a pour on 2 November 2026, curing ends on 9 November and the 28-day test is on 30 November.
What the result means
Dates are calendar days. In cold weather concrete gains strength more slowly, so the same strength takes longer; follow your engineer’s instructions or test results over the calendar.
Assumptions and limits
- Periods are counted in calendar days from the day of the pour.
- Does not predict strength gain; striking and prop removal must follow the engineer’s criteria or test results.
Questions
Why is 28 days used for testing?
Specified strengths are commonly defined at 28 days, so test specimens are crushed at that age to check compliance.
Can I strike formwork sooner in hot weather?
Sometimes, but only on the engineer’s say-so, ideally backed by early-age strength tests.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.