Calculator Inputs
Example Data Table
| Scenario | Model | Days | Workers | Visitors/week | Loss% | Buffer% | Typical units to order |
|---|---|---|---|---|---|---|---|
| Small interior fit-out | Disposable | 30 | 15 (peak) | 2 | 3 | 10 | ~520 |
| Concrete & rebar phase | Disposable | 60 | 55 (peak) | 8 | 6 | 12 | ~4,600 |
| Steel erection crew | Reusable | 90 | 40 (peak) | 6 | 5 | 15 | ~175 |
| High dust demolition | Disposable | 21 | 28 (peak) | 4 | 8 | 20 | ~1,150 |
| Mixed trades, long schedule | Reusable | 180 | 65 (peak) | 10 | 7 | 15 | ~520 |
Formula Used
base_units = daily_units × project_days
total_units = ceil(base_units × (1+loss%) × (1+buffer%))
initial_stock = ceil((sets_needed + sets_needed×turnaround_days) × (1+buffer%))
life_cycles = ceil(project_days ÷ service_life_days)
total_units = ceil((initial_stock × life_cycles) × (1+loss%))
How to Use This Calculator
- Choose the protection type and the usage model.
- Enter duration, headcount, and expected compliance level.
- Add weekly visitor volume and working days schedule.
- For disposable items, set daily usage per person.
- For reusable items, set turnaround and service life.
- Adjust loss and buffer rates to match your site.
- Set pack size and rounding if ordering by boxes.
- Press Calculate, then export CSV or PDF.
Professional Guide: Planning Eye Protection on Construction Sites
1) Why accurate counts reduce downtime
Construction schedules rely on continuous access control and PPE issuance. When eye protection runs short, crews pause, supervisors reassign tasks, and productivity drops. A simple count based only on worker headcount often misses visitors, audits, and short-term trades. This calculator converts those variables into a repeatable procurement plan.
2) Key drivers: headcount, visitors, and compliance
Daily demand starts with planning workers (average or peak) and then applies an adjustable compliance rate. For example, a 50-person peak at 95% compliance results in 47.5 effective users. Visitors per week are distributed across workdays, adding fractional daily demand that becomes meaningful on longer projects.
3) Disposable vs reusable: different stock behavior
Disposable items follow a consumption model: units per person per day multiplied by project days. Reusable items behave like circulating assets: you need enough sets for issuance, plus extra sets while cleaning or inspection occurs. Service life controls replacement cycles, while loss and damage add realistic overage.
4) Buffer, loss, and pack rounding in procurement
A buffer typically ranges from 5% to 20% depending on supplier lead time and site criticality. Loss and damage rates capture scratches, broken frames, and unreturned items. If suppliers sell full boxes, rounding to pack multiples prevents partial-box ordering errors and makes the purchase order cleaner.
5) Cost visibility and reporting
With a unit cost and currency code, the calculator provides an estimated total cost that can be compared against budget allowances. Exporting results supports daily toolbox briefings, safety documentation, and client reporting. Update inputs when project phases change, especially during peak staffing weeks.
FAQs
1) Should I plan with average or peak headcount?
Use peak headcount when shortages could stop work. Use average for steady, low-variability projects, then re-run weekly when staffing changes or new trades mobilize.
2) What compliance rate should I enter?
Enter the expected percentage of people who must wear eye protection in your work zones. If the whole site is mandatory, use 100%. If some areas are excluded, lower the rate.
3) How do visitors affect the count?
Visitors are converted from weekly volume to a daily average using workdays per week. This prevents under-ordering when inspections, client tours, or deliveries happen regularly.
4) How do I choose disposable usage per person per day?
Use 1 for a standard daily issue. Increase to 1.5–3 for dusty demolition, frequent lens scratching, or multiple shifts. Use site observations to refine the value.
5) What does cleaning turnaround mean for reusable items?
Turnaround is the time a set is unavailable due to cleaning, inspection, or drying. Longer turnaround requires more spare sets to keep issuance uninterrupted during busy periods.
6) Why are loss and buffer separate?
Loss/damage covers items that disappear or become unusable. Buffer covers extra stock for uncertainty such as delayed deliveries, unexpected staffing increases, or urgent replacement needs.
7) Does the PDF export save my data?
The PDF is generated in your browser from the most recent results shown on the page. For repeatable reporting, export CSV as well and store it with your safety documentation.