How do I calculate the shelf life of a product?

Shelf life is calculated as the number of days between the manufacture date and the expiry date. Use the "Shelf Life Duration" mode in this calculator: enter the manufacture date and expiry date, and it will show the total shelf life in days, weeks, months, and years. For products without a printed expiry date, refer to USDA FoodKeeper guidelines or use our built-in food database.

How long does milk last in the fridge?

Pasteurized milk typically lasts 7 days in the refrigerator when unopened, and about 5 days once opened. UHT (ultra-high temperature) milk can last 6-9 months unopened at room temperature, but once opened it should be refrigerated and used within 7-10 days. Always keep milk at or below 4°C (40°F) — storing it in the back of the fridge (coldest area) rather than the door extends its life.

Shelf Life Calculator

Purchase Date

Expiry Date

Check how much shelf life is left from purchase and expiry dates.

Shelf Life Remaining

100.0%

Fresh· 7 days left

Used 0%100% remaining

May 20, 2026May 27, 2026

Timeline

From manufacture to expiry

Manufactured

May 20, 2026

Expires

May 27, 2026

Total Shelf Life

7days

Days Elapsed

0days

What Is Shelf Life?

Understanding product expiry and food safety

Shelf life is the period during which a product remains safe, effective, and of acceptable quality when stored under recommended conditions. For food, this means the time from manufacture until it should no longer be consumed. For medicine and cosmetics, it indicates when the product may lose potency or become unsafe.

It is important to distinguish between different date labels: "Best Before" indicates quality rather than safety (the product may still be safe after this date), while "Use By" is a safety date — food should not be consumed after this date. "Sell By" is a guide for retailers, not consumers.

Best Before

Quality

Safe past this date

Use By

Safety

Discard after this date

Sell By

Retail

Guidance for stores

How Storage Conditions Affect Shelf Life

Temperature and handling impact product longevity

Storage conditions are the single biggest factor in determining how long a product lasts. The same food item can have dramatically different shelf lives depending on temperature, humidity, and whether the package has been opened.

Room Temperature

20-25°C (68-77°F). Suitable for pantry staples, canned goods, and dry foods. Avoid direct sunlight.

Refrigerated

0-4°C (32-40°F). Extends life of dairy, meat, and most perishables. Keep below 4°C to inhibit bacterial growth.

Frozen

Below -18°C (0°F). Maximizes preservation for months or years. Quality may decline over time even if food stays safe.

Opened

Once opened, products have reduced shelf life due to exposure to air, moisture, and bacteria. Reseal and refrigerate when possible.

Common Shelf Life Mistakes

Avoid these pitfalls to reduce food waste and stay safe

Confusing "Best Before" with "Use By"

"Best before" is about quality — food may be safe to eat past this date. "Use by" is about safety and should be strictly followed, especially for meat, dairy, and ready-to-eat foods.

Ignoring the "opened" clock

Once opened, most products have a much shorter shelf life than the printed date suggests. Milk may say 14 days on the label, but once opened it should be used within 5 days.

Storing food at wrong temperatures

Keeping your fridge above 4°C (40°F) accelerates spoilage. Use a fridge thermometer to verify — many home refrigerators run warmer than expected.

Not following FIFO

First In, First Out — always use older products before newer ones. Place newly purchased items behind existing stock to reduce waste.

Shelf Life Formulas

How expiry dates and remaining life are calculated

Expiry Date

Expiry Date = Manufacture Date + Shelf Life

Remaining Life %

% Remaining = (Expiry − Today) / (Expiry − Manufacture) × 100

Shelf Life Duration

Duration = Expiry Date − Manufacture Date

Shelf life values in the built-in database are approximate and based on commonly cited ranges from USDA FoodKeeper guidelines and FDA general guidance. They are not item-specific lab results. Actual shelf life varies by brand, formulation, packaging, and storage conditions. Always check product labels and consult manufacturer guidance for safety-critical decisions.

About the Shelf Life Calculator

How this calculator works

This calculator helps you determine expiry dates, check remaining shelf life, and calculate total shelf life duration for food, medicine, and cosmetics. It includes a built-in database of 45+ common products with shelf life data for different storage conditions (room temperature, refrigerated, frozen, and opened). Select a product to auto-fill shelf life values, or enter custom dates and durations. Results include a color-coded freshness status and visual progress bar.

Frequently Asked Questions

Common questions about shelf life, expiry dates, and food safety

"Best Before" (or "Best By") indicates when a product is at peak quality — it may still be safe to consume after this date. "Use By" is a safety date, particularly important for perishable items like meat, dairy, and ready-to-eat meals. Food should not be consumed after the "Use By" date. "Sell By" is for retailers and tells stores when to remove products from shelves — consumers typically have 1-5 days after this date to consume the product.

Temperature is the most critical factor in shelf life. Bacteria multiply rapidly between 4°C and 60°C (40°F and 140°F), known as the "danger zone." Refrigeration (0-4°C) slows bacterial growth significantly — for example, raw chicken lasts 1-2 days refrigerated vs. 9 months frozen. Every 10°C increase in temperature roughly doubles the rate of chemical reactions that cause spoilage (the Q10 rule). Always keep perishables below 4°C and frozen items below -18°C.

It depends on the type of date label. Food past its "Best Before" date may still be safe if it looks, smells, and tastes normal — quality may have declined but safety is often unaffected for days or weeks. However, food past its "Use By" date should be discarded, especially for high-risk items like soft cheese, deli meats, and pre-prepared salads. Canned goods are often safe well past their dates if the can is not dented, bulging, or rusted. When in doubt, follow the rule: "When in doubt, throw it out."

Opening a product typically reduces shelf life significantly because it introduces air, moisture, and bacteria. For example, pasteurized milk may have a 14-day shelf life sealed but only 5 days once opened. Mayonnaise goes from 3 months sealed to about 2 months opened (refrigerated). Always check the "once opened" guidance on product labels. The calculator includes an "Opened" storage condition that uses reduced shelf life values from our food database.

Remaining shelf life percentage shows how much of the total shelf life is still left. It is calculated as: (Days until expiry ÷ Total shelf life days) × 100. This is useful for businesses that need to track inventory freshness. Many retailers use thresholds: above 50% is "Fresh," 25-50% is "Use Soon," below 25% is "Expiring Soon," and 0% means expired. Our calculator color-codes these statuses automatically.

Foods with the longest shelf life include: honey (indefinite if sealed), sugar (2+ years), white rice (2+ years), dried pasta (2+ years), canned goods (2-5 years), salt (indefinite), and dried beans (1-2 years). Freeze-dried foods can last 25-30 years. Among refrigerated items, hard cheeses (6 months) and butter (3 months) last the longest. Proper storage in cool, dry, dark conditions maximizes shelf life for all products.

Key strategies: (1) Practice FIFO — First In, First Out, use older items before newer ones. (2) Store food properly — keep fridge at 0-4°C, don't overload it. (3) Plan meals and buy only what you need. (4) Freeze items before they expire — most foods freeze well for months. (5) Understand date labels — "Best Before" doesn't mean "unsafe after." (6) Use this calculator to track expiry dates and get reminders when products are approaching their end of shelf life.

Yes. Medicine shelf life is strictly regulated — expired medication may lose potency or become harmful. The FDA requires drug manufacturers to provide expiration dates based on stability testing. Never use medicine past its expiry date. Cosmetics have a PAO (Period After Opening) symbol showing months of use after opening — typically 6-12 months for mascara, 12-24 months for foundation, and up to 36 months for sunscreen. Our calculator includes common medicine and cosmetics in the product database.

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Last updated Apr 5, 2026