Calculator Inputs
Enter minutes for each activity. Use multipliers for realistic field planning.
Example Data Table
| Scenario | Samples | Locations | Crew | Min/sample | Travel (min) | Efficiency | Overhead % |
|---|---|---|---|---|---|---|---|
| Concrete cylinders, single site | 12 | 1 | 2 | 15 | 25 | 0.95 | 8 |
| Soil compaction checks, multi-zone | 30 | 4 | 3 | 12 | 60 | 0.88 | 12 |
| Asphalt cores with heavy documentation | 8 | 2 | 2 | 22 | 40 | 0.85 | 15 |
Use the “Load example values” button to populate a typical scenario.
Formula Used
First, calculate total base minutes for one person:
BaseMinutes = (Samples × MinutesPerSample) + (Locations × SetupPerLocation) + TravelMinutes + SafetyMinutes + (Samples × ReportingPerSample) + QAReviewMinutes + MiscMinutes
Convert to hours and scale by crew size:
CrewHours = (BaseMinutes ÷ 60) × CrewSize
Apply planning multipliers:
TotalLaborHours = (CrewHours ÷ Efficiency) × (1+Overhead%) × (1+Contingency%) × (1+Rework%)
How to Use This Calculator
- Enter sample count, locations, and crew size.
- Add realistic minutes for sampling, setup, travel, and reporting.
- Set efficiency below 1.00 for congestion or restricted access.
- Use overhead and contingency to reflect planning allowances.
- Click Calculate labor hours to view results above the form.
- Download the CSV or PDF report for sharing and records.
Sampling scope and crew planning
Construction sampling rarely fails because of test methods; it fails because labor is underestimated. This calculator converts sampling scope into labor-hours by combining sample count, locations, and crew size. Use it for soil, asphalt, concrete, coatings, weld NDT support, or environmental grabs. Set the project name so exports remain traceable during review meetings and contract closeout weekly.
Time inputs and field realism
Minutes per sample should include collection, labeling, sealing, and basic handling. Setup per location captures access, barricades, permits, and tool staging. Travel minutes represent moving between zones or to a staging area. Reporting minutes per sample reflect chain-of-custody, photos, GPS notes, and logbook entries. QA and misc minutes capture supervision, standby, packaging, and handoff delays.
Efficiency and overhead controls
Efficiency is a practical productivity dial. Values below 1.00 model congestion, restricted access, or weather friction; values above 1.00 represent highly repeatable work with minimal interruption. Overhead adds coordination time such as briefings, mobilization, and supervisor touchpoints. Contingency protects the plan from unplanned site events, while rework allowance covers resamples and rejected runs.
Scheduling and overtime insight
Total adjusted labor-hours are converted into estimated crew-days using shift length and crew size. Regular hours per person-day set the threshold for overtime reporting. This helps planners compare alternatives: add crew members, extend shifts, or reduce travel by clustering locations. The hours-per-sample metric supports bid unit rates and quick benchmarking across similar projects.
Documentation and audit readiness
Exports provide a simple evidence trail for cost control. CSV supports spreadsheet review, while the PDF summary packages inputs, assumptions, and outcomes for approvals. When stakeholders ask why labor increased, the breakdown table shows where time is consumed. Keep inputs aligned with site procedures, safety rules, and client reporting requirements to avoid surprises.
FAQs
1) What does “total adjusted labor-hours” represent?
Total adjusted labor-hours are crew person-hours after applying efficiency, overhead, contingency, and rework. It is the best single estimate for planning, staffing, and budgeting the full sampling effort.
2) How should I choose an efficiency factor?
Start at 1.00 for smooth access and repeatable tasks. Use 0.85–0.95 for busy sites, long walks, permit delays, or weather impacts. Calibrate using your last two similar jobs.
3) Does crew size reduce the total labor-hours?
No. Person-hours usually rise with added coordination, but this tool treats crew size as scaling work. More crew typically reduces calendar days, not total person-hours, unless you also improve efficiency or cut travel.
4) What is included in overhead and contingency?
Overhead covers coordination time: briefings, mobilization, supervision, and meetings. Contingency is a buffer for unpredictable events like access restrictions, equipment downtime, or re-sequencing. Keep both transparent for stakeholder approvals.
5) How is overtime estimated?
Overtime is calculated as hours above regular hours per person-day, multiplied by crew size and estimated crew-days. Adjust regular hours and shift length to match your labor agreement and site policy.
6) Can I use this for laboratory work?
Yes, if you translate lab steps into minutes. Enter setup as bench preparation, sampling as test runs, reporting as documentation, and QA as review. For complex labs, separate workflows and calculate each as its own scenario.