This Formula Helps You Determine Whether a Purchase Is Worth the Money

Have you ever bought a pair of shoes, only to find that you have worn them less than 10 times in a year? Or purchased a household appliance like an air fryer that seemed like a good deal but barely gets used?

The real value of these items depends on how often you use them and how long they last.

For many Kenyans, making money decisions involves balancing everyday expenses such as rent, transport, food, school fees and savings. When money is limited, getting value from every purchase becomes particularly important.

One way to do this is by using the cost-per-use formula, a simple budgeting tool that helps you assess whether an item is worth the money you spend on it.

The formula encourages you to look beyond the price tag and consider how much each use of an item effectively costs you. It can help you compare products, avoid unnecessary purchases and decide when spending more upfront could make financial sense.

The cost-per-use formula calculates the amount you spend each time you use an item. The basic formula is: Cost per use = Purchase price ÷ Number of times you use the item.

For example, suppose you buy an item for Ksh6,000 and use it 300 times before replacing it. Its cost per use would be Ksh20. However, if you buy another item for Ksh2,000 but only use it 40 times, its cost per use would be Ksh50.

Although the second item was cheaper to buy, each use effectively cost more.

The formula is particularly useful when comparing items that serve the same purpose but differ in price, durability or how frequently you expect to use them. It is also important to remember that these calculations are estimates: the result depends on how long an item actually lasts and how often you use it.

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Here are three ways you can apply the formula to everyday spending decisions in Kenya.

1. Shoes and Clothes: How Much Does Each Wear Cost You?

The cost-per-use formula can help you compare clothes and shoes based on their price and durability.

Suppose you need formal shoes for work and have two options: a pair costing Ksh2,500 and another costing Ksh8,000. If the cheaper pair lasts 100 wears while the more expensive one lasts 400 wears, the calculations are:

• Ksh2,500 shoes: Ksh2,500 ÷ 100 wears = Ksh25 per wear.
• Ksh8,000 shoes: Ksh8,000 ÷ 400 wears = Ksh20 per wear.

Although the second pair costs more upfront, its estimated cost per wear is lower because it lasts longer. These are hypothetical figures, and actual durability depends on quality, care and frequency of use.

The same principle applies to clothes. Before buying an outfit, consider how often you will wear it and whether it suits your everyday needs. An expensive item is not automatically better value, just as a cheap one is not always the most affordable in the long run.

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2. Household Appliances: Is Buying Worth It?

Household appliances can be expensive, so it helps to estimate how frequently you will use them.

Suppose you buy a washing machine for Ksh45,000 and use it three times a week for five years. That translates to approximately 780 washing cycles.

Ksh45,000 ÷ 780 cycles = approximately Ksh58 per cycle.

This calculation covers only the purchase price. Electricity, water, detergent, maintenance and repairs will increase the actual cost.

For a Kenyan household that frequently pays for laundry services, buying a washing machine could offer value over time. However, if you wash clothes occasionally, the upfront expense may be harder to justify. Consider your household's needs, available space and access to reliable water and electricity before purchasing.

3. Gym Equipment: Should You Buy It or Pay for a Gym Membership?

The formula can also help you decide whether to buy fitness equipment or pay for a gym membership.

Suppose you buy a treadmill for Ksh60,000 and use it three times a week for five years, completing approximately 780 sessions.

Ksh60,000 ÷ 780 sessions = approximately Ksh77 per session.

However, if you exercise only once a week for a year before abandoning the treadmill, you will use it about 52 times. Its purchase-price cost per session would rise to approximately Ksh1,154, excluding electricity and maintenance.

A gym membership can be assessed similarly. If you pay Ksh3,000 monthly, each visit costs Ksh250 when you attend 12 times, Ksh500 for six visits, or Ksh1,000 for three visits.

Before committing, consider your existing exercise habits, schedule and convenience. If uncertain, try a short membership first. The key is to estimate usage realistically rather than justify a purchase based on habits you hope to develop.

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How to Use the Formula Before Making a Purchase

The cost-per-use formula does not have a fixed threshold that tells you whether a purchase is worth the money. Instead, it helps you compare options and decide whether the value you expect to get justifies the price.

Start by identifying the item you need, its purchase price and how often you realistically expect to use it. Divide the price by the estimated number of uses over the time you expect to own it.

For example, if a pair of shoes costs Ksh6,000 and you expect to wear them 300 times, their cost per wear is Ksh20. You can then compare it with another pair costing Ksh3,000 that you expect to wear 100 times, giving it a cost per wear of Ksh30.

In this case, the more expensive pair has a lower estimated cost per wear. However, that does not automatically mean you should buy it. You must also consider whether you can afford the upfront cost, whether both pairs meet your needs and whether your estimates of their durability are realistic.

Where possible, compare the cost per use of similar products or compare buying an item with an alternative, such as purchasing a washing machine versus paying for laundry services.

You should also account for additional expenses, including maintenance, repairs and running costs, where relevant. Most importantly, base your calculations on how frequently you are likely to use an item, not how often you hope to use it.

Ultimately, use the formula as a guide rather than a strict rule. A purchase offers better value when its expected usefulness justifies the cost, fits within your budget and makes sense compared with the alternatives. Even an item with a low cost per use may not be worth buying if you do not need it or if purchasing it means neglecting essential expenses, debt repayments or savings