How it works
The calculator compares a subscription to a one-time purchase over the time horizon you choose. It converts all pricing into a monthly equivalent, accumulates costs over time, and identifies the break-even month where the totals intersect.
Inputs and what they mean
You provide the one-time price, a subscription price (monthly or annual), and the number of months you expect to use the product or service. Optional discounts let you model promotional pricing or upfront offers that reduce the purchase price.
The time horizon is the most important input. A subscription that looks cheap for six months can be costly over three years. When you change the usage months, you are essentially telling the calculator how long you will keep paying or how long the one-time purchase will stay valuable to you.
How totals are calculated
The calculator normalizes annual pricing by dividing it by twelve, so the subscription cost is treated as a monthly rate. It then applies any subscription discount you set and multiplies the monthly cost by the number of usage months. The one-time cost is reduced by any upfront discount and counted once.
The result is two comparable totals: the cumulative subscription cost over your timeline and the one-time purchase cost. The difference between these totals is displayed as the delta cost.
Break-even logic
Break-even is the first month when the subscription total equals or exceeds the one-time price. If the subscription never catches up within your usage window, the calculator reports that no break-even occurs during that period.
This point matters because it tells you how long you would need to use the subscription before the one-time purchase becomes the cheaper option. It is a decision anchor, not a prediction. If you plan to cancel before break-even, the subscription is often the better deal. If you plan to keep using the product beyond break-even, ownership typically wins on cost.
Example scenario
Suppose a lifetime license costs $300 and the subscription is $20 per month. Over 12 months, the subscription totals $240, which is cheaper. Over 24 months, the subscription totals $480, which is more expensive. Break-even happens around month 15. That means if you expect to use the product longer than 15 months, the license is usually cheaper.
This example illustrates why time matters. The monthly price alone does not tell the full story. The calculator helps you see the curve rather than guessing based on a single number.
Interpreting the recommendation
The recommendation is based strictly on total cost within your usage window. It does not account for non-price factors like features, convenience, or support. If the totals are close, the tool will indicate a tie and encourage you to consider other factors.
If you want to compare different assumptions, change the inputs and review how the break-even month moves. This sensitivity check is often more valuable than any single run because it reveals where the decision is fragile or stable.
Next steps
When you understand the math, explore the scenario pages. They include presets and explanations tailored to specific decisions like gym memberships, software licensing, or solar installations.