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Packing lunch vs buying lunch calculator
Put your workdays, packing cost and buying cost in: 20 workdays at $5.00 packed is $100.00 a month against $260.00 bought at $13.00, so packing saves $160.00 a month.
★ COMPARISONS · FOOD · PACKING VS BUYING LUNCH
Packing Lunch vs Buying Lunch: Save $160.00 a Month
On the defaults — 20 workdays a month, packing lunch at $5.00 a day against buying lunch at $13.00 a day — packing costs $100.00 a month and buying costs $260.00, so packing saves $160.00 a month and $1,920.00 a year. This is the PACKING-VS-BUYING version — the same workday lunch priced two ways, with a break-even packing cost — the meal-prep-vs-takeout-calculator page is the MEAL-PREP version — home cooking weighed against takeout per meal; the meal-kit-vs-groceries-calculator page is the MEAL-KIT version — a meal kit weighed against groceries per serving; the coffee-shop-vs-home-coffee page is the COFFEE version — a bought coffee weighed against a home coffee; and the meal-allowance-calculator page is the ALLOWANCE version — a daily meal allowance priced over workdays.
What does packing save $160.00 a month mean?
It means that one month of workday lunches costs $100.00 packed and $260.00 bought, so packing saves $160.00 a month — $8.00 a day over 20 workdays — and $1,920.00 over 12 months at the same pace. The break-even is the whole story in miniature: packing breaks even with buying when a packed lunch costs $13.00 a day, exactly the buying price, so any packed lunch under $13.00 a day saves money and any packed lunch over it costs more than buying. The part people get wrong is comparing one lunch to one lunch without the month: $5.00 against $13.00 looks like an $8.00 saving, which it is, but the monthly figure is what a budget feels — $160.00, not $8.00. The other part people get wrong is the reverse — pricing a packed lunch at grocery-bill prices without dividing by portions: a $40.00 shop that makes eight lunches is $5.00 a lunch, not $40.00, and counting the whole shop as one lunch erases the saving entirely.
Three things to check before you trust the number
Is $5.00 really your packed-lunch cost? Five dollars is the ingredients cost per packed lunch, and it is the figure the packing total turns on: the $7.00-packing branch saves $120.00 against the $160.00 headline, so a $2.00 daily difference is $40.00 a month over 20 days. Price the lunch from the ingredients actually used — bread, filling, fruit, drink — divided by the portions they make, not from the whole grocery bill, and not from a guess.
Is $13.00 really your bought-lunch cost? Thirteen dollars is the full bought price, and it is the figure the buying total turns on: the $10.00-buying branch saves $100.00 against the $160.00 headline, so a $3.00 daily difference is $60.00 a month. If you always add a drink, a tip, or a delivery fee, it belongs in the $13.00 — a bought lunch priced without its usual extras understates buying and understates the saving.
Is 20 workdays really your lunch month? Twenty workdays is the monthly count, and it is the figure both totals turn on: the 15-day branch saves $120.00 against the $160.00 headline, so five fewer lunch days are $40.00 less saving. Holidays, remote days, and days you skip lunch are not lunch days — count only the days you actually eat a workday lunch, and average a few honest months rather than taking your fullest month.
Worked example
On the defaults: 20 workdays a month, packing $5.00 a day, buying $13.00 a day.
- Packing total: 20 × $5.00 is $100.00 a month.
- Buying total: 20 × $13.00 is $260.00 a month.
- Monthly saving: $260.00 − $100.00 is $160.00 a month, or $8.00 a day.
- Yearly saving: $160.00 × 12 is $1,920.00 a year.
- Break-even packing cost: $13.00 a day — the buying price itself, where packing and buying cost exactly the same.
And the other way: the packing cost behind a $160.00 monthly saving is $5.00 a day, and the buying cost behind a $160.00 monthly saving is $13.00 a day. With 0 workdays the model honestly shows $0.00 against $0.00 — exactly even — because with no lunch days there is no lunch spend on either side, an edge that shows the day count is entered independently of the prices.
Every branch, checked
- 15 workdays, same costs: 15 workdays, same costs: Packing $75.00 vs buying $195.00 — packing saves $120.00 a month.
- $7.00 packing cost, same days and buying cost: $7.00 packing cost, same days and buying cost: Packing $140.00 vs buying $260.00 — packing saves $120.00 a month.
- $10.00 buying cost, same days and packing cost: $10.00 buying cost, same days and packing cost: Packing $100.00 vs buying $200.00 — packing saves $100.00 a month.
- $15.00 buying cost, same days and packing cost: $15.00 buying cost, same days and packing cost: Packing $100.00 vs buying $300.00 — packing saves $200.00 a month.
The reverses, worked backwards
- Packing cost behind $160.00 a month saving: $5.00 a day — at $5.00 a day the figures are Packing $100.00 vs buying $260.00 — packing saves $160.00 a month.; at the lower neighbor the figures are Packing $80.00 vs buying $260.00 — packing saves $180.00 a month.; at the upper neighbor the figures are Packing $120.00 vs buying $260.00 — packing saves $140.00 a month..
- Buying cost behind $160.00 a month saving: $13.00 a day — at $13.00 a day the figures are Packing $100.00 vs buying $260.00 — packing saves $160.00 a month.; at the lower neighbor the figures are Packing $100.00 vs buying $240.00 — packing saves $140.00 a month.; at the upper neighbor the figures are Packing $100.00 vs buying $280.00 — packing saves $180.00 a month..
What the defaults assume
The defaults are 20 workdays a month, $5.00 a day packed and $13.00 a day bought, so the headline is one worker choosing between a packed lunch and a bought lunch for a full working month. The model is two multiplications and a subtraction: the packing total is workdays times the packing cost, the buying total is workdays times the buying cost, and the saving is the buying total minus the packing total, times 12 for the year. The packing reverse is checked at $1.00 either side, because $1.00 a day over 20 days is $20.00 a month; the buying reverse is checked at $1.00 either side for the same reason. The break-even packing cost is the buying cost itself, by definition — the packed price at which the two totals meet. The model does not include the time spent packing, containers, or the value of variety and social lunches out — price those in judgement, not in this arithmetic, and weigh the $160.00 against what packing actually costs you in time.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Packing total | workdays × packing cost | $100.00 — 20 × $5.00. |
| Buying total | workdays × buying cost | $260.00 — 20 × $13.00. |
| Monthly saving | buying total − packing total | $160.00 — $260.00 − $100.00, packing wins. |
| Yearly saving | monthly saving × 12 | $1,920.00 — $160.00 × 12. |
| Saving per day | buying cost − packing cost | $8.00 a day — $13.00 − $5.00. |
| Break-even packing cost | buying cost | $13.00 a day — the packed price where the two totals meet exactly. |
| Packing cost behind a target monthly saving | buying cost − target monthly saving ÷ workdays | $5.00 — $13.00 − $160.00 ÷ 20. |
| Buying cost behind a target monthly saving | packing cost + target monthly saving ÷ workdays | $13.00 — $5.00 + $160.00 ÷ 20. |
| Packing total as a share of the buying total | packing total ÷ buying total | 38.46% — $100.00 ÷ $260.00, packing costs under four-tenths of buying. |
| 15 workdays, same costs | same model | Packing $75.00 vs buying $195.00 — packing saves $120.00 a month. |
| $7.00 packing cost, same days and buying cost | same model | Packing $140.00 vs buying $260.00 — packing saves $120.00 a month. |
| $10.00 buying cost, same days and packing cost | same model | Packing $100.00 vs buying $200.00 — packing saves $100.00 a month. |
| $15.00 buying cost, same days and packing cost | same model | Packing $100.00 vs buying $300.00 — packing saves $200.00 a month. |
| Packing cost behind $160.00 a month saving | reverse | $5.00 a day: Packing $100.00 vs buying $260.00 — packing saves $160.00 a month. |
| Buying cost behind $160.00 a month saving | reverse | $13.00 a day: Packing $100.00 vs buying $260.00 — packing saves $160.00 a month. |
| 0 workdays | same model | Packing $0.00 vs buying $0.00 — exactly even. |
| Negative workdays | same model | Workdays per month — 0 or more. |
| Negative packing cost | same model | Packing cost — $0 or more. |
| Negative buying cost | same model | Buying cost — $0 or more. |
Who uses this
- A worker deciding whether to pack lunch — $100.00 packed against $260.00 bought is a $160.00 saving, but only if the $5.00 packed price is honest about ingredients.
- A household budgeting two lunches — the saving doubles with two packed lunches, and the branches price a dearer packed lunch or a cheaper bought lunch at once.
- A budgeter checking a food claim — the reverses recover the packing cost or the buying cost behind any quoted monthly saving.
- A new starter planning the first month — the break-even packing cost shows exactly how generous a packed lunch can be before buying wins.
Accuracy & limitations
Figures are the model’s own arithmetic on the numbers you type, computed from unrounded values and displayed rounded HALF_UP to 2dp. The main limitation is the inputs, not the arithmetic: whether the packed price divides the grocery shop honestly by portions, whether the bought price includes its usual drink, tip or fee, and whether the workday count is an honest average are all judgement calls, and this page prices the figures you enter without checking them. This page is a calculation tool, not financial advice.
Cite this calculator
Packing lunch at $5.00 a day for 20 workdays costs $100.00 a month vs buying lunch at $13.00 a day for $260.00: packing saves $160.00 a month, $1,920.00 a year. Source: Bright Side Kit, https://brightoolbox.com/packing-lunch-vs-buying-lunch/, accessed 29 October 2026.
Frequently asked questions
What is the break-even packing cost?
The packed-lunch price at which packing and buying cost exactly the same: $13.00 a day on these defaults, because that is the buying price. Below $13.00 a day packing saves money; above it, packing costs more than buying.
How do I price a packed lunch honestly?
Divide the grocery shop by the portions it makes: a $40.00 shop that makes eight lunches is $5.00 a lunch. Count bread, filling, fruit and drink actually used, and leave out groceries eaten at other meals — the whole shop is not one lunch.
Should the bought price include a drink and tip?
Yes, if you always pay them: the honest bought price is what leaves your pocket for the lunch, drink, tip or delivery fee included. A bought lunch priced without its usual extras understates buying and understates the saving.
What if I only pack some days?
Then split the month: packed days at the packing price plus bought days at the buying price, against every day bought. This page compares all-packed against all-bought; a mixed month sits between the two totals in proportion to the packed days.
Does packing time count?
Not in this arithmetic, which prices money only. If packing takes twenty minutes a day you value highly, weigh that time against the $8.00 a day saved — for some people the time is worth more than the saving, and that is a fair reason to buy.
How is this different from the meal prep vs takeout calculator?
This page prices a workday lunch two ways — packed against bought — while the meal prep page prices home cooking against takeout per meal. Use this page for the daily lunch decision, and the meal prep page for the wider cooking-versus-takeout choice.