Repair Café Waste Diversion Impact Calculator

Introduction

This Repair Café Waste Diversion Impact Calculator helps you estimate how much waste your events keep out of landfill, how much embodied carbon you avoid, and how many volunteer hours and specialist follow-ups you are likely to need. It is designed for repair café organizers, circular economy nonprofits, and municipal waste teams who want quick, order-of-magnitude impact numbers for planning and reporting.

How to use

Enter your event cadence, item volume, repair success rate, average item weight, embodied carbon factor, volunteer roster, diagnostic time, parts budget, and specialist follow-up rate. The calculator turns those event assumptions into monthly and annual waste diversion, carbon savings, staffing coverage, and triage needs.

Start with recent sign-in sheets or intake logs when possible. If you do not have measured weights or carbon factors yet, run conservative low, expected, and high scenarios so your grant report or municipal dashboard does not depend on a single optimistic assumption.

How this repair café impact calculator works

The tool takes your typical repair café cadence (events per month), item flow (items brought and successfully repaired), and staffing pattern (volunteers and shift length). It then scales those monthly inputs to show approximate annual diversion, carbon savings, and labor needs.

At a high level, the calculator follows these steps:

1. Estimate items successfully repaired per event.
2. Convert successful repairs into diverted weight and avoided embodied carbon.
3. Scale results from per event to monthly and annual totals.
4. Estimate volunteer hours available and typical diagnosis capacity.
5. Approximate how many items will require specialist follow-up.

Key formulas

Let:

• E = repair café events per month
• I = average items brought per event
• R = successful repair rate (percent)
• W = average weight per item (kg)
• C = embodied carbon per item (kg CO₂e)
• V = volunteers per event
• H = volunteer shift length (hours)
• D = average diagnosis time per item (minutes)
• T = percentage of items needing specialist follow-up (percent)

A core calculation is the number of items successfully repaired per event:

From this, the calculator derives monthly and annual landfill diversion (by weight) and carbon savings:

• Items repaired per month = Items_repaired,event × E
• Items repaired per year = Items_repaired,event × E × 12
• Landfill diversion per month (kg) = Items_repaired,event × E × W
• Landfill diversion per year (kg) = Items_repaired,event × E × W × 12
• Carbon savings per month (kg CO₂e) = Items_repaired,event × E × C
• Carbon savings per year (kg CO₂e) = Items_repaired,event × E × C × 12

Volunteer hours and triage capacity are based on simple time estimates:

• Volunteer hours per event = V × H
• Volunteer hours per month = V × H × E
• Diagnosis capacity per event (items) ≈ (V × H × 60) ÷ D
• Items needing specialist follow-up per event = I × (T ÷ 100)

Understanding landfill diversion and embodied carbon

Landfill diversion in this context means the total weight of items you keep in use through repair rather than sending to disposal. It is a proxy for avoided waste and can be reported in kilograms or tonnes per year.

Embodied carbon (kg CO₂e) is the greenhouse gas impact associated with producing and distributing an item, expressed as kilograms of carbon dioxide equivalent. When you extend the life of a product, you delay or avoid the need for a replacement, which effectively “saves” part of that embodied carbon. This calculator uses your input for embodied carbon per item and scales it by the number of successful repairs.

How to interpret your results

The output panels typically show:

• Monthly and annual diverted weight – useful for waste reports and circular economy dashboards.
• Monthly and annual carbon savings – indicative climate impact, often used in funding or CSR reporting.
• Total volunteer hours – helps with scheduling, volunteer recruitment, and recognizing contributions.
• Diagnosis capacity – checks whether your volunteers can realistically assess all incoming items.
• Specialist follow-ups – a rough count of items that may need external repair partners or follow-up clinics.

In broad terms, for a neighborhood-scale repair café:

• Diverting a few hundred kilograms per year is a solid start and shows that your events are working.
• Crossing 1,000–2,000 kg/year suggests a mature, well-attended program with strong community engagement.
• Above 5,000 kg/year often indicates a larger city-wide network or frequent events with high throughput.

Worked example

Suppose a community group runs:

• 3 repair café events per month (E = 3)
• 48 items brought per event (I = 48)
• 62% successful repair rate (R = 62)
• Average weight 3.2 kg per item (W = 3.2)
• Embodied carbon 45 kg CO₂e per item (C = 45)
• 22 volunteers per event, 4-hour shifts (V = 22, H = 4)
• Average diagnosis time 18 minutes per item (D = 18)
• 22% of items need specialist follow-up (T = 22)

Items successfully repaired per event:

Items_repaired,event = 48 × (62 ÷ 100) ≈ 29.8 ≈ 30 items

Diversion and carbon savings per year:

• Items repaired per year ≈ 30 × 3 × 12 = 1,080 items
• Landfill diversion per year ≈ 30 × 3 × 3.2 × 12 ≈ 3,456 kg (about 3.5 tonnes)
• Carbon savings per year ≈ 30 × 3 × 45 × 12 = 48,600 kg CO₂e (about 48.6 tonnes CO₂e)

Volunteer effort and capacity:

• Volunteer hours per event = 22 × 4 = 88 hours
• Volunteer hours per month = 88 × 3 = 264 hours
• Theoretical diagnosis capacity per event ≈ (22 × 4 × 60) ÷ 18 ≈ 293 items, comfortably above the 48 items expected.

Items needing specialist follow-up per event:

Specialist items,event = 48 × (22 ÷ 100) ≈ 10.6 ≈ 11 items

Over a year, this is around 11 × 3 × 12 ≈ 396 items where you may want partnerships with specialist repairers or follow-up sessions.

Example scenarios and typical ranges

The table below compares three stylized scenarios to give you a feel for scale. These are not presets in the calculator, just illustrative benchmarks.

Use this table as a sense check. If your inputs suggest much higher or lower diversion than expected for your scale, revisit your assumptions around item weights, repair success rate, or embodied carbon per item.

Assumptions, limitations, and data sources

This calculator is intentionally simple and makes several assumptions:

• Average item weight and carbon – You provide a single average weight and embodied carbon value per item. In reality, a mix of textiles, electronics, and furniture will have very different profiles. If you have better category-level data, adjust your averages accordingly.
• Repair success is independent per item – The calculation assumes each item has the same probability of being successfully repaired, which may not hold if you specialize in a few repair types.
• Linear scaling over 12 months – Monthly activity is simply multiplied by 12 to produce annual figures. Seasonal variations, special events, or one-off campaigns are not explicitly modeled.
• Embodied carbon attribution – The tool treats each successful repair as if it “saves” the full embodied carbon of a replacement item. In practice, life cycle assessments often allocate only a portion of embodied carbon to life extension, depending on how much additional life you add.
• Diagnosis time and capacity – The diagnosis capacity is a rough theoretical upper bound and does not account for breaks, complex jobs, or time spent on education and conversation.

For embodied carbon and typical weights, many programs draw on published life cycle assessment (LCA) databases, academic studies, or manufacturer environmental product declarations. If your municipality or organization has its own factors for common product categories, you can substitute those values for more accurate reporting.

Using this tool alongside other resources

This calculator is best used as a planning and communication aid rather than a formal inventory. For detailed greenhouse gas accounting, you may also want to reference broader carbon footprint or waste diversion tools, and, where available, local guidance on reporting reuse and repair outcomes.

Pairing these quick estimates with qualitative stories from volunteers and participants can help make a stronger case to funders, policymakers, and community stakeholders for sustaining and scaling your repair café work.