| Scenario | Pack | Dose | Conditions | Net pack cost | Estimated washes | Cost per wash |
|---|---|---|---|---|---|---|
| Liquid, standard household | 1,500 ml @ 12.99 | 50 ml | Standard, normal, medium, warm | 12.99 | ~30.0 | ~0.433 |
| Powder, hard water | 3,000 g @ 18.50 | 75 g | Large, normal, hard, warm | 19.43 (tax + shipping) | ~30.1 | ~0.646 |
| Pods with subscription savings | 42 count @ 24.99 | 1 count | Standard, light, medium, cold | 21.24 (savings applied) | ~40.0 | ~0.531 |
- Effective dose = Base dose × (load × soil × hardness × temperature) ÷ concentration
- Dose with wastage = Effective dose × (1 + wastage% ÷ 100)
- Estimated washes from pack = Pack size ÷ Dose with wastage
- Net pack cost = (Price × (1 − discount%) × (1 − subscription%) × (1 − bulk%)) + shipping then × (1 + tax%).
- Cost per wash = Net pack cost ÷ Estimated washes
- Enter your pack price and pack size from the label.
- Enter the dose you actually use per wash.
- Match the units: volume with volume, mass with mass, or count with count.
- Select conditions like load size, soil, and water hardness.
- Add discounts, shipping, tax, and wastage if needed.
- Press Calculate to see cost per wash above the form.
- Use CSV or PDF exports to share or archive results.
Dose accuracy drives the real price
The label dose is a baseline, but measuring habits change costs quickly. A 1,500 ml bottle with a 50 ml dose targets 30 washes. If the average pour creeps to 60 ml, washes drop to 25 and cost per wash rises 20%. Using a marked cap or dosing cup improves repeatability and helps the calculator match your routine.
Water hardness and soil level matter
Hard water can reduce cleaning efficiency, so many households increase dosage. In the calculator, “hard” water applies a practical uplift, which can cut washes per pack by 10–15% depending on other settings. Heavy soil adds another uplift, reflecting extra surfactant demand. Track two scenarios—normal and heavy weeks—to see a realistic monthly range rather than a single number.
Temperature choices can shift detergent needs
Cold cycles save energy but may require slightly more detergent or longer agitation to achieve comparable results, especially for oils. Hot cycles can improve solubility and sometimes allow a small reduction. Use the temperature selector to model these effects without changing the product. If you switch seasons, recalculate and compare the annualized cost difference per 100 loads for clarity.
Discounts and add-ons change the true pack cost
Shelf price is not the full cost. Subscriptions, bulk deals, and coupons reduce the base, while shipping and tax increase it. When you combine a 10% coupon and 5% subscription saving, the net reduction is 14.5% (compounded), not 15%. Enter each component separately so the calculator reflects how receipts actually work.
Use cost per wash for smarter comparisons
Cost per wash allows fair comparison across liquids, powders, and pods. Two products with different pack sizes can be ranked by their net per-wash cost after conditions and wastage. For budgeting, multiply by your weekly loads; for bulk buying, estimate total washes needed for a quarter. Exporting to CSV or PDF keeps your assumptions documented for later review.
1) What if my pack size is in ounces?
Convert to milliliters or grams first, then enter the value. Use 29.57 ml per US fluid ounce for liquids and 28.35 g per ounce for powders. Keep package and dose units in the same family.
2) How do I use this for pods or tablets?
Set package unit to count and dose unit to count. Enter pack size as the number of pods and dose as pods per wash, usually 1 or 2.
3) Why does concentration factor reduce the dose?
A higher concentration means more cleaning power per unit, so you need less product to reach the same performance. The calculator divides the adjusted dose by the concentration factor to model that effect.
4) What is a good wastage percentage?
For careful measuring, 1–3% is common. If pouring directly from a large bottle or dealing with spills, 5–10% may be more realistic. Set it to 0% only if you measure very consistently.
5) How accurate are the load and hardness multipliers?
They are practical defaults meant for estimating. Brands and washers differ, so use them as a starting point. If your results feel off, adjust dose per wash to match your real usage and rerun.
6) Can I compare two detergents?
Yes. Run the calculator once for each product and export the CSV or PDF. Compare cost per wash and estimated washes, keeping the same conditions and wastage so the comparison stays fair.