Subscriptions for pet food are sold on convenience and a discount. The convenience is real: the bag arrives before the old one ends. The discount is the part to check, because shipping, minimum orders and a price that moves can erase it. And there is a third problem that discount banners do not mention: a subscription delivers on a calendar, but a bag empties according to what the pet eats, and the two rarely match. This guide shows how to compare a subscription with your usual way of buying, how to find the break-even discount, what the interval does to your stock over a year and what to read in the terms. The prices are examples. The Pet Food Bag Duration Calculator gives the days a bag lasts.
The comparison
subscription cost per bag = price × (1 − discount) + shipping per bag normal cost per bag = shelf price + the cost of getting it (travel, shipping)
If you collect the food in a shop on a trip you are making anyway, the normal cost is the shelf price. If you make a special trip, add fuel and parking. If you usually order online without a subscription, add the shipping you pay.
An example: 36.00 bag, 4.00 shipping
| Offer | Calculation | Cost per bag | Against 36.00 |
|---|---|---|---|
| 5% off, 4.00 shipping | 36 × 0.95 + 4 | 38.20 | +2.20 |
| 10% off, 4.00 shipping | 36 × 0.90 + 4 | 36.40 | +0.40 |
| 11.1% off, 4.00 shipping | 36 × 0.889 + 4 | 36.00 | 0 |
| 15% off, 4.00 shipping | 36 × 0.85 + 4 | 34.60 | −1.40 |
| 10% off, free shipping | 36 × 0.90 | 32.40 | −3.60 |
| 5% off, free shipping | 36 × 0.95 | 34.20 | −1.80 |
The break-even discount is shipping ÷ price = 4 ÷ 36 = 11.1%. A discount below that is a loss; above it, a saving. The headline percentage tells you little without the shipping.
Annual saving
A bag lasting 34 days means 365 ÷ 34 = 10.7 bags a year.
| Offer | Saving per bag | Saving per year |
|---|---|---|
| 15% off, 4.00 shipping | 1.40 | 15.0 |
| 10% off, free shipping | 3.60 | 38.6 |
| 5% off, 4.00 shipping | −2.20 | −23.6 |
Even a good offer saves tens, not hundreds. That is worth having, but it does not justify keeping stock you do not need.
The interval problem
A subscription delivers every so many weeks. A bag lasts a number of days. If the two differ, stock either builds up or runs short.
| Interval | Days between deliveries | Deliveries a year | Bags used a year | Difference |
|---|---|---|---|---|
| 4 weeks | 28 | 13.0 | 10.7 | +2.3 bags in surplus |
| 5 weeks | 35 | 10.4 | 10.7 | −0.3 bags (about 11 days short) |
| 6 weeks | 42 | 8.7 | 10.7 | −2.0 bags short |
(A bag lasts 34 days at 294 g a day.) A 4-week plan builds a surplus of 2.3 bags a year, which is 23 kg of food in the cupboard and 83 of money spent early. A 5-week plan runs short by about 11 days a year, which you fill with an occasional shop purchase. The 5-week plan is closer, and the shortfall is easy to manage. If the interval cannot be set to match, skip a delivery when the surplus grows.
When the daily amount changes
If the dog’s food amount changes, the bag’s life changes. A weight-loss plan that cuts the daily amount from 294 g to 265 g makes a bag last 37.7 days instead of 34. A subscription set at 5 weeks (35 days) now builds up a small surplus. Whenever the amount changes, recalculate the interval; see pet food reorder reminders. A change of food has the same effect.
The terms to read
- Price: is the subscription price fixed, or does it follow the shelf price? Does the discount apply to the first order only?
- Shipping: is it free, free above a threshold, or charged per delivery?
- Interval: can you set it in weeks and change it later?
- Skips and pauses: can you skip a delivery, and by when must you tell them?
- Cancellation: is there a fee, and can you cancel online?
- Substitutions: what happens if the food is out of stock? Will a different product be sent?
- Dates: is the best-before date on delivered bags reasonable?
Keep a note of the date by which a change must be made. A cut-off a week before delivery is common.
Compare by cost per 1,000 kcal
If you are comparing different foods, use cost per 1,000 kcal and not price per kg; see price per 1,000 kcal. A subscription on a cheaper-per-calorie food is a double saving; a subscription on a dearer food may still cost more even with a discount. The Pet Food Price per 1,000 kcal Calculator takes price, weight and kcal per kg. For the bag-size question, see is a bigger bag cheaper.
A worked example
Dev buys a 15 kg bag of 3,500 kcal/kg food at 49.50 for his 30 kg dog, who eats 410 g a day. A subscription offers 8% off and 5.00 shipping.
| Step | Working | Result |
|---|---|---|
| Bag lasts | 15,000 ÷ 410 | 36.6 days |
| Bags a year | 365 ÷ 36.6 | 10.0 |
| Subscription cost per bag | 49.50 × 0.92 + 5.00 | 50.54 |
| Normal cost per bag | 49.50 | |
| Difference | 50.54 − 49.50 | +1.04 per bag |
| Break-even discount | 5 ÷ 49.50 | 10.1% |
| Annual cost of subscribing | 1.04 × 10.0 | +10.4 |
At 8% off with 5.00 shipping, the subscription costs Dev 1.04 more per bag and about 10 more a year. He decides not to subscribe, but sets a reminder instead, and checks again if the shipping becomes free or the discount reaches 10.1%.
The break-even for other prices
The break-even discount depends on the price of the bag and the shipping.
| Shelf price | Shipping 4.00 | Shipping 6.00 |
|---|---|---|
| 20.00 | 20.0% | 30.0% |
| 36.00 | 11.1% | 16.7% |
| 50.00 | 8.0% | 12.0% |
| 80.00 | 5.0% | 7.5% |
Subscriptions pay off best on large, dear bags, where shipping is a small share of the price. On a small bag, even a generous discount can lose to the shipping.
First-order discounts
Some offers give a large discount on the first order and a small one afterwards. Take 20% off the first bag, then 5% off the rest, with free shipping, on a 36.00 bag and 10.7 bags a year.
| Bag | Price | Saving |
|---|---|---|
| First | 28.80 | 7.20 |
| Next 9.7 bags | 34.20 each | 1.80 each, 17.46 in total |
| Year one | 24.66 |
The saving in year one is 24.66, and in later years only 19.3 (10.7 × 1.80). Judge the offer by the long-run discount, and treat the first-order bonus as a one-off. Check that the price stays at the discounted level; some subscriptions raise it after a few deliveries. If you cancel after the first order, you have saved the 7.20 without any of the commitment, provided there is no fee.
Three questions before you subscribe
- Would I buy this exact food anyway for the next year?
- Can I match the interval to the days a bag lasts?
- Can I skip or cancel easily?
If the answer to any is no, the discount is not worth the risk.
A decision in four lines
- Work out the days a bag lasts and the bags a year.
- Work out the subscription cost per bag, including shipping.
- Compare with your normal cost per bag, including any travel.
- Multiply the difference by the bags a year, and decide if the saving justifies the commitment.
For Dev’s 15 kg bag, the sum was +1.04 per bag, so the answer was no. For a 36.00 bag with 10% off and free shipping, it is 3.60 a bag and about 38.6 a year, so the answer is yes, provided the interval fits. Put the date of the next review in your calendar, because discounts and shipping rules change.
Common mistakes
- Looking only at the headline discount.
- Ignoring shipping.
- Setting an interval that does not match the bag.
- Forgetting to change the plan when the amount changes.
- Missing the cut-off for a skip.
- Comparing different foods by price per kg.
- Letting a surplus grow past the best-before dates.
Quick summary
- Subscription cost per bag = price × (1 − discount) + shipping; compare it with what you pay normally.
- Break-even discount = shipping ÷ shelf price; 4.00 on 36.00 is 11.1%.
- A 34-day bag on a 4-week plan builds 2.3 bags of surplus a year; a 5-week plan runs about 11 days short.
- Recalculate the interval when the daily amount or the food changes.
- Read the terms for price changes, skips, substitutions and cancellation.
- Use the Pet Food Bag Duration Calculator.
Frequently asked questions
How do I know if a subscription is cheaper?
Compare discounted price plus shipping with the price you pay without it, per bag, for the same food.
What discount do I need to break even?
Shipping divided by the shelf price. With 4.00 shipping on a 36.00 bag that is 11.1%.
How often should a subscription deliver?
As often as a bag lasts. A bag that lasts 34 days suits a 5-week interval with a small buffer, or a 4-week interval with an occasional skip.
What if the shelf price rises?
Check whether the subscription price is fixed or follows the shop price, and whether the discount still applies.
Can I skip or cancel?
Read the terms. You want to be able to skip, change the interval and cancel without a fee.
Do subscriptions change what my pet eats?
No, but a stock of the wrong amount may tempt you to feed more. Keep to the daily amount.
Sources
- Pure arithmetic: subscription cost per bag = price × (1 − discount) + shipping; break-even discount = shipping ÷ price
- Your retailer's subscription terms (the source for discounts, shipping, price changes and cancellation)
Related calculators
- Pet Food Price per 1,000 kcal CalculatorCompare two foods fairly by price per 1,000 calories instead of price per bag.
- Pet Food Bag Duration CalculatorFind out how many days a bag of pet food will last at the amount you feed.
- Pet Food Run-Out Date CalculatorFind the date a bag of food will run out and when to reorder.
Keep reading
- Is a Bigger Bag of Pet Food Cheaper?How to test bulk bag savings: cost per day by bag size for a 294 g a day dog, the yearly saving, the opened-bag time limit that erases it and the largest useful bag.
- Pet Food Reorder Reminder SetupHow to work out when pet food runs out and when to reorder: bag grams ÷ daily grams, a lead-time rule, a worked 10 kg bag example, a reminder table and an order log.
- Price per 1,000 kcal: Compare Pet Food FairlyWhy price per 1,000 kcal is the fair way to compare pet foods: the formula, worked dog and cat examples across dry, wet and premium foods, and cost per day.
- Comparing Three Dog Foods: A Worked ExampleCompare three dog foods by cost per day and per 1,000 kcal: 0.87, 1.06 and 1.20 a day for a 20 kg dog, why the cheapest bag per kg may not be cheapest.