Simple formulas. Clear assumptions.

Ship or Spend is built to answer one practical question: which option costs less based on the numbers in front of you? Every calculator runs locally in your browser and exposes the assumptions behind its result.

How we calculate results

We compare like with like. Discounts become monetary savings, pack sizes become unit prices, subscriptions become totals over the same period, and warranties become expected repair costs. We round displayed currency to two decimal places while the comparison uses the underlying numerical values.

What the calculators do not know

The tools cannot verify store eligibility rules, product quality, future prices, taxes, cancellation terms, repair probabilities, or whether you genuinely need an item. Results are estimates—not financial, legal, insurance, or purchasing advice.

Testing principles

Each tool is checked against hand-calculated examples, zero-value inputs, equal-cost outcomes, and decision reversals. We also verify routes, metadata, mobile overflow, and browser errors before publishing major changes.

Privacy and maintenance

No account or database is required. Inputs stay in the browser and are not saved by Ship or Spend. Users provide current prices themselves, which avoids stale retailer-specific data and keeps the calculators useful without hidden feeds or APIs.

Corrections

If a formula or explanation appears wrong, do not rely on the result. Recheck the store terms and your inputs. We prefer correcting a transparent formula over disguising uncertainty behind a proprietary score.