Prep Lists, Pars, and Yields for Line Cooks
Set pars from real sales, write a prep list in the right order, and use yield math to buy and portion the right amount.
Table of contents
A good night on the line is mostly decided before the first ticket prints. If you prep too little, you 86 a best seller at 8 p.m., which means taking it off the menu for the night. If you prep too much, food goes in the trash and the kitchen loses money. Getting this right is a skill built on simple math, and it's one of the clearest signs that a cook is ready for more responsibility.
This work builds on what you already do. Now you stop waiting for someone to hand you a prep list, and you start working out what the list should say.
What You Will Be Able to Do
- Set a par from sales history and a forecast.
- Work out yield percent, and use it to order or prep the right amount.
- Find the real cost of a portion from a yield test.
- Scale a recipe, and know what doesn't scale in a straight line.
- Build a prep plan that fits your time, your cooler space and the cooling rules.
Terms You Need
| Term | What it means |
|---|---|
| Par | The amount of an item you want ready before service |
| On hand | What you already have that's still good to use |
| AP (as purchased) | The weight of food as it arrives, with skin, bones, trim and all |
| EP (edible portion) | The weight left after trimming, peeling or cooking |
| Yield percent | EP divided by AP, shown as a percentage |
| Prep list | What has to be made today, how much, and by whom |
Setting a Par
A par isn't a guess. It comes from three numbers: how many guests you expect, how often they order the item, and how much cushion you want.
- Get the forecast. Check reservations, private events, the weather, and what happened on the same day last week and last year.
- Find the order rate. Your point of sale system can show how many of an item sold compared with total covers. A cover is one guest served.
- Multiply. Forecast covers times order rate gives the expected sales.
- Add a cushion. Many kitchens add about 10 to 20 percent to cover a run on one item. Your chef sets this.
- Subtract on hand. The result is what goes on the prep list.
Worked example. Friday's forecast is 160 covers. Over the last four Fridays, 22 percent of covers ordered the burger.
- Expected sales: 160 x 0.22 = 35.2, so about 35 burgers
- With a 15 percent cushion: 35.2 x 1.15 = 40.5, so a par of 41
- On hand from yesterday, still in date: 12 patties
- Prep today: 41 - 12 = 29 patties
A par changes with the day. Monday's burger par might be 15. A fixed par that stays the same all week wastes food on slow days and runs out on busy ones.
Set the cushion by what the item costs and how long it lasts. A cheap item with a long shelf life can have a wider cushion. Fresh fish or cut avocado needs a tight one, because extra product gets thrown away.
Yield: What You Buy Is Not What You Serve
A 10-pound case of onions doesn't give you 10 pounds of diced onion. Skins, root ends and tops are lost. Meat loses more, through trimming and then through cooking.
The formula is simple:
Yield percent = EP weight divided by AP weight, times 100
Worked example: how much to prep. You peel and dice a 10-pound bag of onions and end up with 8.9 pounds. Your yield is 8.9 divided by 10, which is 89 percent.
A soup batch calls for 12 pounds of diced onions. To find what you need to start with, divide by the yield as a decimal:
12 divided by 0.89 = 13.5 pounds of whole onions
A common mistake is to multiply instead. 12 x 0.89 gives 10.7 pounds, which is far too little. Divide when you're working back from what you need to what you must buy.
Running a Yield Test
The numbers in books are a start, but your own numbers are better. They depend on your supplier, the grade of product and how each cook trims it. To run a yield test:
- Weigh the product as it arrives.
- Trim or peel it the way your kitchen normally does, and weigh what's usable.
- If it's cooked, cook it to your standard, let it rest, and weigh it again.
- Slice or portion it to spec, and count what you get.
- Write down the date, the supplier and the cook's name, and test again if the supplier changes.
Worked example: a beef roast. You buy a 20-pound top round at $6.00 a pound, so it costs $120.
| Step | Weight | Running yield |
|---|---|---|
| As purchased | 20 lb | 100% |
| Trimmed | 17.5 lb | 87.5% |
| Cooked, rested and sliced | 12.25 lb | 61.25% |
Your menu calls for a 5-ounce portion.
- 12.25 pounds x 16 ounces = 196 ounces
- 196 divided by 5 = 39.2, so 39 full portions
- $120 divided by 39 = about $3.08 for each portion
The cost for each usable pound is $120 divided by 12.25, or about $9.80. That's far above the $6.00 on the invoice. Pricing a dish from the invoice number alone is one of the most common ways a kitchen loses money without knowing why.
This math also shows why trimming matters. If a rushed cook trims the same roast down to 16 pounds instead of 17.5, you lose portions on every roast, every week.
Scaling a Recipe
The conversion factor tells you how much to multiply every ingredient by.
Conversion factor = new yield divided by old yield
Worked example. A sauce recipe makes 4 quarts and calls for 1.5 pounds of shallots. You need 10 quarts.
- 10 divided by 4 = 2.5
- Shallots: 1.5 x 2.5 = 3.75 pounds
Weigh ingredients wherever you can. Volume is less reliable, since a packed quart and a loose quart of chopped herbs aren't the same amount. Remember the basics: 16 ounces to a pound, 4 quarts to a gallon, and water weighs about 2 pounds per quart. Don't assume that an ounce of weight and a fluid ounce match for anything other than water.
Not everything scales in a straight line:
| Ingredient or step | Why it changes | What to do |
|---|---|---|
| Salt and strong spices | They can overpower a big batch | Start with less, taste and adjust |
| Thickeners | Large batches can hold heat and thicken more | Add in stages |
| Reductions | A bigger pot has less surface for its volume, so it reduces more slowly | Reduce by look and taste, not by time |
| Cooking time | A larger batch heats and cools more slowly | Use a thermometer |
| Mixing | Big batches take longer to blend evenly | Work in batches if your equipment is small |
Always taste a scaled recipe before it goes on the line, and write down what you changed.
Building the Prep List
Once you know your numbers, put the work in an order that actually fits the day.
- List every item below par, with the amount to make.
- Mark how long each one takes, including time when you don't need to stand over it.
- Start the longest items first, especially anything that simmers, braises or chills.
- Fill the waiting time with hands-on work, such as knife work during a braise.
- Leave cold-held items and anything fragile for last, so they spend the least time out of the cooler.
- Finish with time to spare for tasting and setting your station.
Worked example. Doors open at 5:00 p.m., and you start at 1:00 p.m.
| Time | Task | Why it goes here |
|---|---|---|
| 1:00 | Sear and start the short ribs | Longest cook, about 3 hours in the oven |
| 1:30 | Start the stock | Simmers without much attention |
| 1:45 | Portion 29 burger patties | Hands-on work while the oven runs |
| 2:30 | Cut vegetables, blanch and shock | Needs your full attention |
| 3:15 | Make sauces, taste, strain | Needs the stock |
| 4:00 | Pull the short ribs and check them | Fork-tender is the test, not the clock |
| 4:15 | Set the station and check backups | Leaves time to fix what's missing |
| 4:45 | Taste every item with the chef | Last check before doors open |
Write a name beside each task if more than one person is prepping. A list without names tends to leave the worst jobs undone.
Cooling Is a Planning Problem
A cook can make more food in an afternoon than the kitchen can cool safely. Plan for that.
Under the FDA Food Code, cooked TCS food (food that needs time and temperature control for safety) must cool from 135°F to 70°F within 2 hours, and to 41°F within a total of 6 hours. Your local code may differ.
Worked example. Your 5-gallon batch of stock comes off the heat and reaches 135°F at 3:40 p.m. It must be at 70°F by 5:40 p.m. and at 41°F by 9:40 p.m. Those deadlines land right in the middle of service, when nobody has time to stir an ice bath.
So plan it differently:
- Start the stock earlier, so it's cooling before the rush.
- Split it into smaller containers or shallow pans.
- Use an ice bath or an ice paddle, and stir.
- Make sure there's a shelf open in the walk-in before you start.
- Assign one person to take and log temperatures, and write that on the prep list.
Never put a full, hot stockpot straight into a reach-in. It can't cool fast enough, and it warms up everything around it.
Warning: The FDA calls improper cooling a major contributor to bacterial foodborne illness. If a batch misses the 2-hour limit, tell your chef or person in charge right away. Depending on your local code and how far past the limit it is, it may need to be reheated to 165°F and cooled again, or thrown out. Don't just put it away and hope.
Dates and Rotation
Under the Food Code, ready-to-eat TCS food made in-house and kept for more than 24 hours must be marked. It can be held for up to 7 days at 41°F or below, and the day it was made counts as Day 1.
Worked example. A sauce made on Tuesday must be used or thrown out by the end of the next Monday.
If you combine an older item with something new, the new mixture takes the date of the oldest ingredient. A salad made on Friday with chicken cooked on Tuesday carries Tuesday's date. This catches people out, so it's worth planning for.
Plan your pars around these dates. Large batches of an item that sells slowly often lead to waste. Two small batches a week may cost more labor, but they can cost less in thrown-out food.
Waste Tells You What to Change
Keep a simple waste log: the item, the amount, the reason, and the day. After a week or two, a pattern shows up.
Worked example. You throw out 8 portions of short rib in a week, at a food cost of $7 each. That's $56 a week, or about $2,900 a year. A small cut in the Monday and Tuesday pars fixes most of it.
| What the log shows | Likely cause | What to change |
|---|---|---|
| Same item thrown out on the same day each week | The par is too high for that day | Set a lower par for that day |
| Item runs out early on Saturdays | The cushion is too thin | Raise the Saturday par |
| Lots of trim going in the trash | Trimming is careless, or the wrong cut is being bought | Retrain, or talk to the chef about the spec |
| Food thrown out for being past date | Poor rotation, or batches that are too big | Check first in, first out, and make smaller batches |
| Sauce broken or burned | Too much rushed cooking | Move it earlier on the prep list |
Good trim can often go to use in stock or a staff meal, if the chef allows it and it's been handled safely. Never use food that's past its date, or that's been out of temperature.
Common Mistakes
| Mistake | What it costs |
|---|---|
| Using the same par every day | Waste on slow days, 86s on busy ones |
| Multiplying by yield when you should divide | You come up short on every batch |
| Pricing from the invoice instead of the EP weight | The dish costs more than anyone realizes |
| Scaling salt straight up and not tasting | A whole batch is ruined |
| Starting a big batch too late to cool it | A food safety failure in the middle of service |
| Forgetting the oldest date on mixed items | Food is kept beyond its limit |
Check Your Understanding
1. The forecast is 200 covers, and 15 percent of guests usually order the salmon. Your chef uses a 10 percent cushion. You have 6 portions on hand. How many do you prep?
200 x 0.15 = 30 expected. 30 x 1.10 = 33 for the par. 33 - 6 = 27 portions to prep.
2. You trimmed a 15-pound case of green beans and got 13.2 pounds. What's your yield, and how much do you need to buy for 20 pounds of trimmed beans?
13.2 divided by 15 = 0.88, so 88 percent. 20 divided by 0.88 = about 22.7 pounds as purchased.
3. A roast costs $90, and you get 30 portions after trimming and cooking. Your chef wants to run a 25 percent bigger portion. What happens to your portion count and cost?
You'd get 30 divided by 1.25, or 24 portions. $90 divided by 24 is $3.75 each, up from $3.00.
4. A soup recipe scaled from 2 gallons to 6 gallons tastes too salty, even though you multiplied everything by 3. Why might that be?
Salt doesn't always scale in a straight line, and a larger pot can change how much liquid is lost. Start with less salt in a big batch and adjust to taste.
5. You made chicken salad on Thursday with chicken cooked on Monday. What date goes on it?
Monday's date, since a mixture keeps the date of its oldest ingredient. If Monday is Day 1, it has to be used or thrown out by the end of Sunday.
Key Takeaways
- A par comes from forecast covers, order rate and a cushion, minus what's on hand.
- Yield percent is EP divided by AP. Divide by it to work back to what you need to buy.
- Run your own yield tests, because invoice price isn't portion cost.
- Scaled recipes need tasting, since salt, thickeners and reductions don't scale evenly.
- Plan big batches around the 2-hour and 6-hour cooling limits, or your local code's limits.
- Use a waste log to change your pars.