What does saving $180.00 a month on tomato basil soup mean?
It means making at home costs $90.00 for 20 days while buying costs $270.00 for the same 20 days — a gap of $9.00 a serving, $180.00 a month, $2,160.00 over a year. The home total is 33.33% of the buying total, so every bought serving of tomato basil soup you replace with a homemade serving keeps $9.00 in your pocket. The break-even buying price is $4.50 a day: a café serving of tomato basil soup at any price above $4.50 loses to homemade, and only a serving of tomato basil soup at or below $4.50 ties or beats it.
Output · formula · meaning
| Output | Formula | What it means |
|---|
| Home total per month | days × home cost per serving | $90.00 — 20 × $4.50. |
| Buying total per month | days × buying cost per serving | $270.00 — 20 × $13.50. |
| Monthly saving | buying total − home total | $180.00 — $270.00 − $90.00. |
| Yearly saving | monthly saving × 12 | $2,160.00 — $180.00 × 12. |
| Break-even buying price | home cost per serving | $4.50 a day — the bought price at which home stops winning. |
| Home cost behind a target saving | buying cost − target saving ÷ days | $4.50 — $13.50 − $180.00 ÷ 20. |
| Buying cost behind a target saving | home cost + target saving ÷ days | $13.50 — $4.50 + $180.00 ÷ 20. |
| Days behind a target saving | target saving ÷ (buying cost − home cost) | 20 — $180.00 ÷ $9.00. |
Three things to check before you trust the number
First, the home cost must be the full per-serving cost: tomatoes, basil, onion, garlic and broth, priced per serving, plus the oil or cream you always finish it with. Tomatoes are cheap in season and dear out of it, but the basil and the broth are where the money sits in winter — pricing only the tomatoes makes homemade look cheaper than it is. Second, the buying price must be what you actually pay per serving, including delivery or service charges on that tomato basil soup — a menu price without the extras understates the buying total. Third, the day count must match reality: 20 days means a serving of tomato basil soup on 20 days of the month, whether homemade or bought, and counting days you skip inflates both totals and the saving.
Worked example
Days 20, home $4.50, buying $13.50. Home total: 20 × $4.50 = $90.00. Buying total: 20 × $13.50 = $270.00. Monthly saving: $270.00 − $90.00 = $180.00. Yearly saving: $180.00 × 12 = $2,160.00. Drop to 10 days and the saving falls to $90.00 a month; drop to 15 days and it is $135.00 a month; rise to 25 days and it climbs to $225.00 a month; rise to 30 days and it reaches $270.00 a month. The saving scales exactly with the days, because the $9.00 per-serving gap never changes.
Every branch, checked
A home cost of $5.00 with the same days and buying cost gives home $100.00 vs buying $270.00, a saving of $170.00 a month. A buying cost of $13.00 with the same days and home cost gives home $90.00 vs buying $260.00, a saving of $170.00 a month. Fifteen days with the same home and buying costs gives home $67.50 vs buying $202.50, a saving of $135.00 a month. Thirty days with the same home and buying costs gives home $135.00 vs buying $405.00, a saving of $270.00 a month. Each branch changes exactly one input, so the difference from $180.00 isolates that input.
The reverses, worked backwards
The home cost behind $180.00 a month saved is $4.50: at $4.00 the figures are home $80.00 vs buying $270.00, a saving of $190.00 a month, and at $5.00 they are home $100.00 vs buying $270.00, a saving of $170.00 a month — a $0.50 step moves the saving by $10.00, because it applies to all 20 days. The buying cost behind $180.00 a month saved is $13.50: at $13.00 the saving is $170.00 a month, and at $14.00 it is $190.00 a month — a $0.50 step moves the saving by $10.00, because it applies to all 20 days. The days behind $180.00 a month saved are 20: at 15 days the saving is $135.00 a month, and at 30 days it is $270.00 a month — five days down moves the saving by $45.00, and ten days up moves it by $90.00.
What the defaults assume
The defaults assume one serving of tomato basil soup on each of 20 days, a steady $4.50 home cost and a steady $13.50 bought price, all year. Real tomato basil soup habits cluster around cold-weather weekday lunches, so the honest use is to enter your average month, or to run the calculator once per stretch of the year and add the stretches. A pot of tomato basil soup also rewards batch cooking: tomatoes simmer down well, and a pot that makes 8 servings divides its tomato, basil and broth cost by 8. Zero days is the honest edge: home $0.00 vs buying $0.00, exactly even. Negative inputs are rejected, and a home cost above the buying price flips the verdict honestly: at a buying price of $3.50 against $4.50 home, home costs $20.00 more a month over 20 days, and buying wins.
Who uses this
A daily tomato basil soup buyer weighing a homemade habit: the $180.00 monthly gap is the prize, and the $2,160.00 yearly gap is the reason to keep tomatoes, basil and broth on hand. A parent planning family lunches: the home line prices a serving of tomato basil soup made at home against the serving of tomato basil soup bought at the café on the way to work. A home cook testing prices: the break-even of $4.50 a day is the floor a home cook must beat, and the buying line is the price a customer compares against. A household cutting food spending without giving up tomato basil soup: the days line shows exactly how much each skipped tomato basil soup day is worth.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is in the inputs. A home cost that omits the basil or the broth, a buying price that omits delivery, or a day count that includes skipped days will each move the answer by exactly the amount of the error, every month. The model does not include your time, the cost of a soup pot bought once, or the value of a café serving of tomato basil soup you enjoy more — price those separately, and re-check the comparison when ingredient or café prices change. This page is a calculation tool, not financial advice.
Cite this calculator
Home tomato basil soup $4.50 vs $13.50, over 20 days: home $90.00 vs $270.00, saves $180.00 a month, $2,160.00 a year. Break-even $4.50 a day. Free calculator. Source: Bright Side Kit, https://brightoolbox.com/making-tomato-basil-soup-at-home-vs-buying-tomato-basil-soup/, accessed 31 October 2026 (2026-10-31).
Frequently asked questions
What counts in the home cost per serving?
Everything in one serving: tomatoes, basil, onion, garlic and broth, priced per serving of tomato basil soup, plus the oil or cream you finish it with. A pot of tomato basil soup that makes 8 servings divides its tomato, basil and broth cost by 8; leaving out the basil understates the home line.
Fresh or canned tomatoes — does it change the comparison?
Only through the price: in summer, fresh tomatoes are cheap and the home line falls; in winter, canned tomatoes are usually cheaper and steadier. Either way, enter the price you actually pay per serving — the method is the same, the cost is what moves.
Should I count my time spent preparing it?
Not in this comparison, which prices ingredients against the café price. If your time matters to you, value it separately: at $20.00 an hour, an hour of preparation a month adds $20.00 to the home line.
Why is the break-even exactly the home cost?
Because home wins whenever the bought price exceeds the home cost per serving: at a bought price of $4.50 the two totals tie, and above it every serving saves the difference. That is why the break-even buying price is $4.50 a day.
Does buying ever win?
Yes — whenever the home cost rises above the bought price. At a buying price of $3.50 against $4.50 home, home costs $20.00 more a month over 20 days, and buying wins by exactly that amount.
How do I use the yearly saving?
Multiply the monthly saving by 12: $180.00 × 12 = $2,160.00. That is the year total if the habit holds steady; for a habit that runs only part of the year, multiply by the months it actually runs.