Example data table
| Scenario | Concentrate | Ratio | Batch | Ready-to-use | Mix cost/L | RTU cost/L | Savings |
|---|---|---|---|---|---|---|---|
| Weed control spray | 1.0 L @ $18.99 | 1:20 | 5.0 L | 1.0 L @ $7.99 | $0.9043 | $7.9900 | ~88.68% |
| Foliar feed | 500 mL @ $14.50 | 1:100 | 10.0 L | — | $0.0287 | — | Compare when RTU is added |
Use the calculator for accurate values with your prices and ratio.
Formula used
- Concentrate fraction = C / (C + W)
- Concentrate per liter of mix = fraction × 1.0 L
- Mix cost per liter = (BottlePrice / BottleConcentrateLiters) × fraction + WaterCostPerLiter × (1 − fraction)
- Total mix from bottle = BottleConcentrateLiters / fraction
- Ready-to-use cost per liter = RTUPrice / RTULiters
- Savings percent = (RTUCostPerL − MixCostPerL) / RTUCostPerL × 100
How to use this calculator
- Enter concentrate bottle size and price from the label.
- Type the dilution ratio exactly as recommended.
- Set your usual batch volume for mixing.
- Optionally add ready-to-use size and price for comparison.
- Optionally add application volume and number of uses.
- Press Calculate, then download CSV or PDF if needed.
Why concentrate economics matter in garden programs
Concentrates turn a small purchase into many liters of usable mix. When you normalize every option to cost per liter, label claims become comparable across brands, bottle sizes, and spray formats. This calculator converts units, applies your dilution ratio, and reports mix cost per liter and per gallon for consistent budgeting.
Cost per liter: the most reliable comparison metric
Bottle price alone hides value. A 1 L concentrate at a higher price can still win if the ratio is lean, because the concentrate fraction becomes small. The tool computes concentrate fraction as C/(C+W), then multiplies by concentrate cost per liter. You can also add an optional water cost for RO, delivery, or metered irrigation sources.
Dilution ratios and practical batching accuracy
Most garden concentrates specify a ratio like 1:20 or 1:100. Small ratio changes can shift spending over a season, especially for frequent spraying. The batch section shows exact concentrate and water volumes needed for your chosen batch size, helping you mix consistently and reduce variability between applications.
Planning coverage with an application volume model
If you track how much solution you apply per bed, pot group, or lawn zone, enter volume per use and number of uses. The calculator estimates total mixed volume required and the expected mix cost for that plan. When you also provide a ready-to-use alternative, it estimates total savings for the same target volume.
Using results to reduce waste and improve purchasing
Use “total mix from bottle” to align purchasing with storage and shelf-life limits. If batches per bottle are high, you may prefer smaller bottles to avoid leftover concentrate. For procurement, compare multiple concentrates by entering each bottle’s price and recommended ratio, then select the lowest cost per liter that still meets performance needs.
FAQs
1) What does the dilution ratio field mean?
Enter the label ratio as concentrate parts to water parts, like 1:20. The calculator converts that into a concentrate fraction and computes exact concentrate and water volumes for your batch.
2) Why do you show cost per liter and per gallon?
Cost per liter is ideal for metric labels, while cost per gallon matches many sprayer and retail references. Showing both helps compare products and align with your measuring tools.
3) Can I compare two concentrates directly?
Yes. Enter the first bottle’s details and note the mix cost per liter, then replace inputs with the second product. The lower mix cost per liter usually indicates better value at the same effectiveness.
4) What if my ready-to-use bottle is in mL?
Select mL for the ready-to-use size and enter the label volume. The tool converts to liters internally, then calculates ready-to-use cost per liter and savings versus your mixed solution.
5) Should I include water cost?
Include it when water has a measurable cost, such as delivered water, RO filtration, or metered greenhouse supply. If you leave it blank, the calculator assumes water cost is zero.
6) Why are my savings negative?
Negative savings means the ready-to-use option is cheaper per liter than your mixed solution, given your ratio and bottle price. Recheck the ratio, units, and prices, then compare alternative concentrates.