Laundry Detergent Calculator
Detergent dosing guidance depends on your water hardness, and running out mid-week is an easy way to end up using a rushed, incorrect amount. Enter your laundry habits and water hardness below to see how far a bottle really goes.
Work out how far a bottle of detergent goes
Enter your laundry habits and water hardness to see how often you'll need to restock.
Most of the Midlands and North East
At a 50ml dose per wash, a 2000ml bottle gives you:
40 loads
That's about 8.0 weeks per bottle, or around 7 bottles a year at your current wash frequency.
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Cons
- Lightweight steel frame can wobble with heavy wet towels
- Aluminium
- 18kg / 21m Drying Space
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- Gently heated bars speed up indoor drying without a tumble dryer
- Much cheaper to run than a tumble dryer for everyday laundry
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- Takes up floor space for the duration of drying
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- Folds flat to almost nothing when not in use
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Cons
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Frequently asked questions
Why does water hardness affect how much detergent I need?
Hard water contains more dissolved minerals, which react with detergent and reduce how effectively it lathers and cleans, so manufacturers recommend a higher dose in hard water areas to get the same washing results as in soft water areas.
How do I find out if I have hard or soft water?
Most UK water suppliers publish hardness maps or a postcode lookup on their website. As a rough guide, much of the South and East of England has hard water, while Scotland, Wales and the North West tend to have softer water.
Does using less detergent than recommended save money?
Using too little can leave clothes less clean and cause a build-up of residue and odour over time, particularly with hard water, which may mean re-washing loads — often costing more in the long run than dosing correctly to begin with.
Are detergent tablets or pods a better measure than liquid?
Pods and tablets give a fixed, pre-measured dose regardless of water hardness guidance, which is convenient but less flexible — with liquid or powder detergent, you can adjust the dose to your specific water hardness and load size.
How this calculator works
The calculator uses a standard volume conversion – we assume an average wash load size of 8kg (this is a common size for UK washing machines). It then multiplies this by the volume of detergent you typically use per load. We’ve factored in that most liquid detergents have a concentration around 30%, meaning you’re actually using about 300ml of fluid per wash, regardless of the bottle size. The calculator outputs an estimated number of washes based on these assumptions.
Detergent Volume & Load Size Comparison
| Detergent Bottle Size |
|---|
| 900ml (e.g., Ariel Liquid, 650 washes approx.) |
| 1.25 Litres (e.g., Persil Quick Relief, 450 washes approx.) |
| 2 Litres (e.g., Fairy Non-Bio, 300 washes approx.) |
| 500g Powder (e.g., Dixan Colour, 600 washes approx.) |
Worked example: Calculating Detergent Usage
Let’s say you regularly use a 900ml bottle of Ariel Liquid detergent. You estimate that you wash approximately 8kg of laundry per load, and you consistently use around 300ml of liquid detergent per wash. Entering these figures into the calculator reveals an estimated wash count of 650 loads. This means your current bottle should last you a considerable time before needing replacement – perfect for busy families!
More questions answered
What does ‘8kg’ represent in this calculator?
The 8kg figure is an average load size used commonly in UK households. It's a good starting point, but for heavily soiled items or larger families, you might need to adjust the input accordingly. Consider adding extra loads if you wash bedding frequently.
How accurate are these calculations?
The calculator provides an *estimate* based on average usage patterns. Actual detergent consumption varies significantly depending on soil levels, water hardness (which affects detergent effectiveness), and personal preference for rinse cycles. Always check the detergent packaging for recommended dosage guidelines.
What if my washing machine is smaller?
Reduce the load size input to reflect your machine’s capacity. A smaller load will naturally require less detergent, leading to a higher wash count from your bottle. Don't over-use detergent – it won't clean better and can leave residue.
I use powder detergent; how does this calculator work?
The calculator automatically adjusts for the typical 30% concentration of liquid detergents. Powder detergents often have a higher concentration, so your actual usage might be slightly less. You’ll need to adjust the input volume accordingly.
What is water hardness and how does it affect detergent use?
Hard water reduces the effectiveness of many detergents. In hard water areas (like much of Yorkshire or Lincolnshire), you may need to use more detergent per load than recommended. The calculator assumes relatively soft water; adjust your input if you live in a hard water area.
Can I use this calculator for fabric conditioner?
No, this calculator is specifically designed for liquid or powder laundry detergents. Fabric conditioner usage is typically determined by the manufacturer’s instructions and doesn't factor into detergent calculations.
What if I only wash small loads occasionally?
Reduce the load size input to reflect your smaller loads. This will increase the number of washes you get from your bottle, but it’s still important to avoid over-dosing – use the minimum recommended amount for a small load.
How often should I replace my detergent bottle?
Based on the calculator's results, determine when you’re nearing the end of your predicted wash count. It's better to buy a new bottle before you run out completely and risk unpleasant surprises!
I've used more detergent than the calculator suggested – what should I do?
This often indicates heavily soiled clothes or hard water conditions. Consider pre-treating stains, using an extra scoop of detergent for particularly dirty loads, or contacting your local water board to assess water hardness.
Can this calculator help me choose a different detergent?
While the calculator helps you understand how much detergent you use, it doesn’t directly advise on choosing a specific brand. Consider factors like stain removal performance and suitability for your fabric types when selecting a new detergent.