RD Exam Foodservice Math: FTEs, Food Cost, Yields and Forecasts, Worked Step by Step

Where foodservice math sits in the 2027–2031 outline

CDR doesn't publish a formula list. What it publishes is the outline, and the 2027–2031 RD test specifications name the topics where these calculations live:

The formulas below are standard foodservice definitions, checked against CDR's practice rationales, the Institute of Child Nutrition's school nutrition KPI course, USDA's Food Buying Guide and an open foodservice management textbook.

The handbook says a simple on-screen calculator is provided, a simple handheld test center calculator may be issued, and you must examine and test whichever you use before the exam starts. You also get an erasable note board for setting up the steps.

FTEs: hours needed divided by hours per FTE

Formula: FTE = total hours needed per week ÷ 40, or total hours per year ÷ 2,080 (40 × 52).

Worked example (written by Passy). A tray line needs 3 aides for 6.5-hour shifts, 7 days a week.

1. Hours per week: 3 × 6.5 × 7 = 136.5
2. FTEs: 136.5 ÷ 40 = 3.41

The trap CDR's own practice rationale shows is counting positions instead of hours: in its item, ten 8-hour positions covered 7 days a week need 560 hours, or 14.0 FTEs at 40 hours each, not 10. CDR's item counts only the hours the positions must cover. If a question wants coverage for vacation or sick time added, it has to give you that extra time or factor, so don't add one on your own.

Staffing questions are easy to get wrong by a single step, which is where worked explanations help. At launch, you'll be able to see planned step-by-step explanations for FTE and staffing questions.

Labor productivity: meals per labor hour

Formulas: meals per labor hour = meals served ÷ labor hours. Labor minutes per meal = (labor hours × 60) ÷ meals served.

Worked example. A kitchen serves 1,200 meals a day using 150 labor hours.

1. Meals per labor hour: 1,200 ÷ 150 = 8
2. Labor minutes per meal: 150 × 60 = 9,000 minutes, ÷ 1,200 = 7.5 minutes

A higher meals-per-labor-hour figure means more output for the same labor. Labor minutes per meal moves the other way. In school nutrition, the Institute of Child Nutrition counts meal equivalents (breakfasts and snacks converted into lunch equivalents) and productive paid labor hours, so use the counts the question gives.

Food cost percentage and selling price

Formulas:

• Cost of food sold = beginning inventory + purchases − ending inventory
• Food cost percentage = cost of food sold ÷ food sales × 100
• Selling price from a target food cost percentage = portion cost ÷ target percentage (as a decimal), which is the food cost formula rearranged
• Inventory turnover = cost of food sold ÷ average inventory, where average inventory = (beginning + ending) ÷ 2

The Institute of Child Nutrition's school nutrition course divides food cost by total revenue rather than food sales, so check which denominator the question uses.

Worked example. Beginning inventory $18,000, purchases $42,000, ending inventory $16,000, food sales $125,000.

1. Cost of food sold: 18,000 + 42,000 − 16,000 = $44,000
2. Food cost percentage: 44,000 ÷ 125,000 × 100 = 35.2%
3. Average inventory: (18,000 + 16,000) ÷ 2 = $17,000
4. Inventory turnover: 44,000 ÷ 17,000 = about 2.6

Pricing example. A portion costs $2.40, and the target food cost is 30%: 2.40 ÷ 0.30 = $8.00.

Yields: as purchased (AP) and edible portion (EP)

Formulas:

• Yield percentage = EP weight ÷ AP weight × 100
• AP needed = EP needed ÷ yield (as a decimal)
• Cost per EP pound = AP price per pound ÷ yield (as a decimal)

Worked example. You need 150 portions of 3 ounces of cooked, trimmed product. The yield from AP to EP is 75%, and the AP price is $5.20 a pound.

1. EP needed: 150 × 3 = 450 ounces, ÷ 16 = 28.125 pounds
2. AP to buy: 28.125 ÷ 0.75 = 37.5 pounds
3. Cost per EP pound: 5.20 ÷ 0.75 = about $6.93

Divide by the yield to go from EP to AP. Multiplying instead gives a number smaller than what you need, which is how to spot the error. USDA's Food Buying Guide works its purchasing examples the same way and rounds the AP amount up to make sure enough food is bought.

Recipe conversion and portion scoops

Conversion factor = desired yield ÷ original yield, then multiply every ingredient by it. Going from a 50-portion recipe to 175 portions: 175 ÷ 50 = 3.5. If the portion size changes too, convert total volume or weight first: (new portions × new portion size) ÷ (old portions × old portion size).

Scoop numbers. A scoop's number is roughly the number of level scoops in a quart. USDA's scoop table lists a #8 as ½ cup (4 fluid ounces) and a #16 as ¼ cup (2 fluid ounces), and a quart is 32 fluid ounces, so 8 and 16 level scoops fill it. Use the table for sizes where the quart rule isn't exact, such as a #20 at 3⅓ tablespoons. To count portions, divide the batch volume by the portion volume, in the same units.

Forecasting with a simple moving average

A simple moving average forecasts the next period as the average of the most recent periods, using the number of periods the question specifies.

Worked example. A 4-period moving average, with the last four Tuesdays at 210, 198, 220 and 204 servings: (210 + 198 + 220 + 204) ÷ 4 = 832 ÷ 4 = 208 servings for next Tuesday. For the following week, drop the oldest value and add the newest.

The distractors in CDR's own practice rationale come from using the wrong window: averaging every value given instead of the most recent ones, or picking a single week's count.

When you want more of these in exam conditions, you'll be able to practice calculations inside the planned 1,700-question bank, each with a worked explanation.

Straight-line depreciation and capital budgets

Formula: annual depreciation = (cost − salvage value) ÷ useful life in years.

Worked example. A combination oven costs $24,000, has a salvage value of $3,000 and a useful life of 7 years: (24,000 − 3,000) ÷ 7 = $3,000 a year.

CDR's practice rationale lists the usual wrong turns: ignoring salvage value, adding it instead of subtracting it, and multiplying by a return-on-investment rate that the method doesn't use.

Capital or operating budget? CDR's rationale puts equipment, buildings and land in the capital budget, and day-to-day costs such as food, wages and payroll taxes in the operating budget. The 2027 outline no longer names financial management as a topic, so treat depreciation as lower priority than FTEs, yields and forecasting, but not as zero.

A food cost percentage practice question written by Passy

This is an original question in the exam's style. It isn't a CDR item.

A hospital café had a beginning food inventory of $9,500, purchased $27,000 of food during the month, and ended with $8,500 in inventory. Food sales were $80,000. What was the food cost percentage?

• A. 23.1%
• B. 33.8%
• C. 35.0%
• D. 56.3%

Keyed answer: C. Cost of food sold is 9,500 + 27,000 − 8,500 = $28,000, and 28,000 ÷ 80,000 × 100 = 35.0%. Option B uses purchases alone (27,000 ÷ 80,000). Option A subtracts ending inventory from purchases but leaves out beginning inventory. Option D adds ending inventory instead of subtracting it.

How to practice RD exam foodservice math

1. Write the formula before the numbers. It takes seconds on the note board and prevents most errors.
2. Keep units visible. Ounces to pounds, hours per week to hours per year, percent to decimal.
3. Check that the answer makes sense. AP should be larger than EP, and a 7-day position needs more than 1 FTE.
4. Use a basic calculator when you practice, like the one on the exam, and try the Pearson demo test at pearsonvue.com/CDR to see the on-screen calculator.
5. Mix math into timed sets. At about 70 seconds a question, a calculation you can set up in one pass protects your time, as the RD exam format guide explains. The 20 free RD exam practice questions are a good first check.

If math is your weakest area, give it time in your plan: you can pick a planned access length that leaves room for math review. Clinical formulas, from BMI to tube-feeding rates, are in the RD exam clinical calculations guide.