How this calculator works (and what it assumes)
The model treats your weekly trash weight as the baseline amount of material your household would otherwise send to the landfill. You then choose a percent diverted—the share you expect to keep out of the landfill by composting, recycling, and switching to reusables. The calculator converts that diversion into dollars by applying your disposal cost per pound and adding any rebate per pound you receive for diverted material (for example, bottle deposits or scrap metal).
To keep the estimate realistic, the calculator also subtracts two common costs: an upfront reusable investment (containers, refillable bottles, cloth towels, etc.) and any recurring monthly program fees (for example, compost pickup). If your net savings per month are positive and you entered an investment, the calculator shows a payback period in months.
Inputs and units
- Weekly Trash Weight (lbs): the amount you currently throw away in a typical week. If you do not weigh it, estimate by counting bags and using an average weight per bag.
- Disposal Cost per lb ($): what you effectively pay to landfill trash. If your city charges by bin size, approximate by dividing your monthly bill by estimated monthly pounds.
- Percent Diverted (%): the share of your weekly trash you expect to divert (0–100). This is the main lever in the model.
- Reusable Investment ($): one-time spending on durable alternatives. Enter 0 if you are not buying anything new.
- Rebate per lb ($): money earned per diverted pound (optional). Many households will use 0.
- Monthly Program Fees ($): recurring fees for compost pickup or special recycling services (optional).
- Months: how long you want to model (e.g., 12 for a year).
Formula used
The calculator uses the following structure (matching the JavaScript calculation):
| Term | Meaning |
|---|---|
| Diverted weight | weeklyWeight × months × (diverted ÷ 100) |
| Avoided disposal fees | weeklyWeight × costPerLb × months × (diverted ÷ 100) |
| Rebates earned | weeklyWeight × rebate × months × (diverted ÷ 100) |
| Net savings | (avoided fees + rebates) − investment − (fees × months) |
Worked example (realistic numbers)
Suppose your household produces 10 lbs/week of trash, your effective disposal cost is $0.25/lb, and you plan to divert 60% for 12 months. You also spend $40 on reusables, earn $0.05/lb in rebates, and pay $3/month for compost pickup.
- Diverted weight = 10 × 12 × 0.60 = 72.0 lbs
- Avoided disposal fees = 10 × 0.25 × 12 × 0.60 = $18.00
- Rebates = 10 × 0.05 × 12 × 0.60 = $3.60
- Fees = 3 × 12 = $36.00
- Net savings = (18.00 + 3.60) − 40.00 − 36.00 = −$54.40
In this example, the program fees and investment outweigh the avoided disposal costs. That does not mean “zero waste doesn’t save money”—it means your local pricing matters. Try increasing disposal cost, reducing fees, or modeling a longer time horizon to see when the investment pays back.
Interpreting results
Use the output as a scenario tool:
- Net savings can be negative in the short term if you invest upfront or pay monthly fees. That is normal.
- Diverted vs landfilled pounds helps you sanity-check the scale. If the weights look too small or too large, revisit your weekly weight estimate.
- Payback period appears only when monthly net savings are positive and you entered an investment amount.
Practical ways to raise diversion (without overspending)
Diversion is easiest when you focus on the heaviest categories first. Food scraps are often the largest share by weight, so composting can move the needle quickly. Next, reduce packaging by buying in bulk, choosing refill options, and using reusable containers. Finally, target repeat purchases (paper towels, bottled water, disposable razors) with durable alternatives—ideally one change at a time so you can measure impact.
Limitations
- This calculator does not price your time (washing containers, extra trips, learning new routines).
- Local rules and markets vary; rebates and accepted materials can change.
- The model uses a simple months multiplier for weekly weight; seasonal variation is not automatically handled.
More guidance: making the estimate match your reality
If your results look surprising, the most common cause is an unrealistic disposal cost per pound. Many households pay a flat fee for a bin, so the “true” marginal cost of one extra pound can feel close to zero until you downsize your service tier. In that case, use this calculator as a scenario comparison tool: model today’s situation, then model a smaller bin or fewer pickups and compare the difference.
Another common source of confusion is the diversion percentage. Diversion is not “how much you recycle”; it is “how much of what would have been trash is now diverted.” If you already recycle, your baseline weekly trash weight may already be lower than your total household discards. For best results, measure the weight of what you currently landfill (not what you already divert).
Finally, remember that investments can be optional. You can often increase diversion with low-cost changes first (meal planning, using what you already own, borrowing containers, choosing unpackaged options). Then, once you see stable savings, you can decide whether higher-cost reusables make sense.