★ COMPARISONS · DAILY HABIT #87 · SALAD DRESSING
On the defaults — 20 days at $1.50 made at home versus $4.50 bought — a home salad dressing costs $30.00 against $90.00 bought, so home saves $60.00 a month and $720.00 a year. This is the SALAD DRESSING comparison — the same days-times-price shape as the making-pasta-salad-at-home-vs-buying-pasta-salad page, the making-salsa-at-home-vs-buying-salsa page and the making-egg-salad-at-home-vs-buying-egg-salad page — with the salad dressing prices and the $1.50 break-even worked in full.
Put your days per month, home cost per salad dressing and buying cost per salad dressing in: 20 days at $1.50 home vs $4.50 bought — home $30.00 vs buying $90.00, home saves $60.00 a month, $720.00 over 12 months.
It means 20 days at $1.50 made at home cost $30.00, while the same 20 days bought at $4.50 cost $90.00 — a gap of $60.00 a month, $720.00 over a year of the same routine. The bought dressing costs three times the home dressing, so every bought day you swap for a home day keeps $3.00 in your pocket. Even swapping half the month — 10 home days and 10 bought ones — still saves $30.00 a month.
| Output | Formula | What it means |
|---|---|---|
| Home total per month | days × home cost per salad dressing | $30.00 — 20 × $1.50. |
| Buying total per month | days × buying cost per salad dressing | $90.00 — 20 × $4.50. |
| Monthly saving | buying total − home total | $60.00 — $90.00 − $30.00. |
| Yearly saving | monthly saving × 12 | $720.00 — $60.00 × 12. |
| Break-even buying price | home cost per salad dressing | $1.50 — the bought price at which home stops winning. |
| Home cost behind a target saving | buying cost − (target saving ÷ days) | $1.50 — $4.50 − ($60.00 ÷ 20). |
| Buying cost behind a target saving | home cost + (target saving ÷ days) | $4.50 — $1.50 + ($60.00 ÷ 20). |
| Days behind a target saving | target saving ÷ (buying cost − home cost) | 20 — $60.00 ÷ ($4.50 − $1.50). |
First, price the home dressing honestly: the oil, vinegar or citrus, mustard, garlic, herbs and sweetener, divided by the servings the batch actually makes. A jar that only half gets used before it spoils has a home cost far higher than the per-serving label suggests. Second, use the bought price you really pay, delivery and service charges included — a $3.50 bottle price that arrives at $4.50 a serving is a $4.50 dressing. Third, count only the days you dress a salad: a 20-day month means 20 salad days, not 20 calendar days with a skipped weekend and a soup day tucked in.
Twenty days, $1.50 at home, $4.50 bought. Home total: 20 × $1.50 = $30.00. Buying total: 20 × $4.50 = $90.00. Saving: $90.00 − $30.00 = $60.00 a month, $720.00 over 12 months. Break-even: $1.50 a day — if the bought dressing ever fell to $1.50, the two sides would be exactly even, and below that buying would win. One home day instead of one bought day saves $3.00 on its own.
A $2.00 home cost with the same days and buying cost gives home $40.00 against buying $90.00, saving $50.00 a month. A $3.50 buying cost with the same days and home cost gives home $30.00 against buying $70.00, saving $40.00 a month. Fifteen days with the same home and buying costs give home $22.50 against buying $67.50, saving $45.00 a month. Twenty-five days with the same home and buying costs give home $37.50 against buying $112.50, saving $75.00 a month. Each branch changes exactly one input, so the difference from $60.00 isolates that input.
The home cost behind $60.00 a month saved is $1.50: at $1.00 the figures are home $20.00 against buying $90.00, saving $70.00 a month, and at $2.00 they are home $40.00 against buying $90.00, saving $50.00 a month. The buying cost behind $60.00 a month saved is $4.50: at $3.50 the figures are home $30.00 against buying $70.00, saving $40.00 a month, and at $5.50 they are home $30.00 against buying $110.00, saving $80.00 a month. The days behind $60.00 a month saved are 20: at 15 days the figures are home $22.50 against buying $67.50, saving $45.00 a month, and at 25 days they are home $37.50 against buying $112.50, saving $75.00 a month.
The defaults assume the same routine every month: 20 salad days, a $1.50 home serving and a $4.50 bought serving, with no change in prices or appetite across the year. Real routines vary: a holiday month may hold few salad days and a busy work month many, so the honest use is to enter the average month, or to run the calculator once per stretch of the year and add the stretches. Zero days is the honest edge: $0.00 home against $0.00 bought, exactly even. Negative inputs are rejected, and a home cost above the bought price flips the verdict — at $5.00 home against $4.50 bought, home costs $10.00 more a month.
A weekday salad packer checking the habit: the home line prices the jar, the bought line prices the bottle or deli pot, and the gap is the monthly reason to keep whisking. A family cook scaling the batch: the per-serving home cost falls as the jar grows, and the calculator shows what each ten-cent saving is worth over 20 days. A student on a tight food budget: the break-even price is the shop price at which making it stops paying, so any bottle below $1.50 a serving is genuinely cheaper than home. A meal-prep coach comparing salads: the same days-times-price shape prices dressing next to salsa, pasta salad and other packed sides on equal terms.
The arithmetic is exact for the inputs entered; the judgement is in the inputs. A home cost that ignores a spoiled jar, a bought price that omits delivery charges, or a day count that includes days you never dress a salad will each move the answer by exactly the amount of the error, every month. The model does not include whisking time, energy costs, jars and bottles, or the value of variety — price those separately, and re-check the comparison when shop prices or grocery prices change. This page is a calculation tool, not budgeting advice.
Home salad dressing $1.50 vs $4.50 bought over 20 days: home $30.00 vs buying $90.00, home saves $60.00 a month, $720.00 a year. Break-even $1.50 a day. Source: Bright Side Kit, https://brightoolbox.com/making-salad-dressing-at-home-vs-buying-salad-dressing/, accessed 30 October 2026 (2026-10-30).
The oil, vinegar or citrus, mustard, garlic, herbs and any sweetener, divided by the servings the batch actually makes. If a jar makes ten servings and costs $15.00 in ingredients, the home cost is $1.50 a serving.
Count only those days: about 20 weekdays in a typical month is exactly the default. A month with holidays or travel holds fewer salad days, so enter the real count, not the calendar length.
It should, if you pay it: the bought price is what leaves your pocket for one bought serving. A $3.50 bottle price with a $1.00 delivery share is a $4.50 bought dressing for this comparison.
When the bought price falls to the home cost or below: at $1.50 bought against $1.50 home the two sides are exactly even, and below $1.50 buying is cheaper. Above $1.50, home wins by the gap times the days.
Because each extra day adds one home serving and one bought serving, and the gap between them is $4.50 − $1.50 = $3.00. Days scale the saving directly, which is why the day count matters as much as the prices.
Yes — the shape is days times price on each side, whatever the food is. Change the labels in your head, enter that food's home and bought prices, and the saving, year total and break-even all follow the same method.