| Date/Time | Item | Size | New | Refill | Uses/Month | Months | Per refill | Total |
|---|---|---|---|---|---|---|---|---|
| No calculations yet. Run the calculator to add rows. | ||||||||
| Item | Container | New cost | Refill cost | Uses/Month | Months | Tax % | Discount % |
|---|---|---|---|---|---|---|---|
| Neem Oil Spray | 1 L | USD 14.00 | USD 8.50 | 2 | 12 | 5.5 | 0 |
| Hand Sprayer Cleaner | 750 ml | USD 9.00 | USD 5.25 | 3 | 6 | 0 | 10 |
| Plant Soap Concentrate | 500 ml | USD 11.50 | USD 6.90 | 1 | 12 | 3 | 0 |
These are sample inputs to demonstrate typical garden refill scenarios.
- net_new = new_cost × (1 + tax%) × (1 − discount%)
- net_refill = refill_cost × (1 + tax%) × (1 − discount%)
- per_refill_savings = net_new − net_refill
- purchases = refills_per_month × months
- total_savings = per_refill_savings × purchases
- break_even_refills = ceil(net_new / per_refill_savings) (only when refill is cheaper)
- waste_reduced_g = container_weight_g × purchases (optional estimate)
- Enter the garden item name and container size for clarity.
- Add the price for a new container and the refill price.
- Set how many refills you expect per month.
- Choose a time horizon to project savings over time.
- Optional: include tax/fees and discounts for realism.
- Optional: enable waste reduction and set container weight.
- Click Calculate savings to view results above the form.
- Use CSV or PDF buttons to download your saved results.
Refill pricing benchmarks for common garden liquids
Refill programs are strongest when the refill price stays 25–50% below the new container price. For frequent-use items like sprayer cleaners, insecticidal soaps, and neem oil mixes, that gap can convert small per‑purchase savings into noticeable seasonal savings. If the refill is only 5–10% cheaper, shipping, store travel, or higher taxes can erase the advantage. Track unit cost per liter to validate refill value consistently.
Understanding savings per refill and total savings
This calculator first adjusts both prices using the same tax and discount settings, then subtracts refill cost from new cost. The difference is your per‑refill savings. Total savings multiplies that value by expected refills per month and the chosen time horizon. For example, a 3.00 savings with 2 refills per month across 12 months projects 72.00 in savings.
Break-even refills and smarter buying decisions
Break-even refills estimate how many cheaper refills are needed to “earn back” the value of one new purchase. A low break‑even count suggests refills quickly outperform buying new. If refill cost is higher, break‑even is not applicable, and the report flags the situation. Use this metric when deciding between a refill station and multi-pack new bottles.
Waste reduction estimates for practical sustainability
If you enable waste reduction, the calculator multiplies container weight by the number of refills you plan to buy. For small bottles, 25–60 grams is typical; sturdy trigger sprayers can reach 90–140 grams. Over a year, even modest refill habits can prevent several hundred grams of plastic waste, especially when you reuse the same sprayer head.
Using horizons and frequency to plan seasons
Set refills per month based on real usage, not guesses. For peak growing months, you may use more soap and sprayer cleaner, while dormant months may drop close to zero. Try 6‑month and 12‑month horizons to compare short season budgeting versus annual planning. Use discounts for bulk days or memberships, and run a “worst case” scenario with zero discounts to stay conservative.
Does the calculator assume refill and new sizes are identical?
Yes. Enter prices that match the same container size. If your refill pack is larger or smaller, convert pricing to the same size before comparing.
Why does tax and discount apply to both options?
Many stores apply tax and discounts to both items. Applying the same adjustment keeps the comparison consistent and highlights true price differences.
What if my refill is more expensive than buying new?
Your per‑refill savings becomes negative, and break-even is shown as N/A. Re-check refill pricing, coupon rules, and whether the refill includes extra accessories.
How should I choose refills per month?
Use real usage patterns: how often you finish that volume. If you are seasonal, calculate for the active months only, or run separate scenarios.
Is the waste reduction number precise?
It is an estimate based on the container weight you enter and the number of avoided purchases. For better accuracy, weigh an empty container without liquid.
Why does the PDF show only the latest calculation?
The PDF is a quick single-page summary of your most recent result. Use the CSV export to download every saved row from your session.