We are the MonoTape team. Same product, but a regular size and a big bulk pack sit side by side. "The bigger one has to be the better deal," you think as you reach for it — yet you're never quite sure. Being unable to compare things that differ in both size and price isn't a gut-feeling problem. You have to bring them to a common unit price (per item, per ounce) to compare them at all, and that math is a hassle. In this article we show how to spot the better deal on the spot.
Bigger isn't always cheaper
Say detergent comes in a 40 oz bottle for $7.96 and a 100 oz jug for $16.90. By total price, the bulk one is more expensive. But the number that matters is the price per ounce. The 40 oz is $0.199 per ounce; the 100 oz is $0.169 per ounce. Sure enough, bulk is a bit cheaper. On the other hand, a "3 for $5" deal can actually be pricier than "1 for $1.50." Only by reducing to a unit price do you see the truth.
A standard calculator can produce a unit price too. The problem is that the moment you compute product A's unit price, it vanishes from the screen. Compute B's, and you've lost what A was, so you can't actually tell which is cheaper. Holding two numbers in your head in the aisle is quietly stressful.
Put each unit price on its own line, side by side
In MonoTape you can name and keep each unit price. Keep A and B on separate lines, and both unit prices sit on screen together.
A is $0.199 per ounce, B is $0.169. Because both are visible at once, which is cheaper is obvious. Add a difference line and you know specifically that "B is about three cents per ounce cheaper." Factor in whether you'll use it all, and you can decide which to buy.
Prices change? The comparison updates itself
When a sale changes a price, or you want to compare against a different product, in MonoTape you just rewrite that line's number. The unit prices and the difference recalculate themselves. "If B drops to $12.90 on sale, does it flip?" — just change 16.90 to 12.90 and check. Vary the size or count assumptions and compare as many times as you like.
The bulk-buy question is settled by unit price, not total price. Put each unit price on a line side by side, and let it re-compare as prices change. That's how you stop reaching for "the big one by default" and actually pick the better deal.
MonoTape
A calculator notepad where you label your math and one edit recalculates everything. Unit-price comparisons, shopping totals, split bills — whatever you calculate stays on the tape. Free to use.
Learn more about MonoTapeFrequently asked questions
How do I calculate unit price?
Price divided by size (or count). $7.96 for 40 oz is 7.96 / 40 = $0.199 per ounce. The trick is to bring the products you're comparing to the same unit (per ounce, per item).
Is bulk always the better deal?
No. By unit price the regular size can be cheaper, and bulk packs can be pricier. And if you don't finish it and throw it out, you've lost money anyway. Compare by unit price, then weigh whether you'll use it all.
Can I compare two products side by side?
Yes. MonoTape keeps each unit price on a separate line, so both sit on screen at once. Add a difference line and you know exactly how much cheaper one is.
Is it free?
Yes. Labeled calculations, references, auto-recalculation, and tape-style history — every feature mentioned here is free. It works on both iPhone and Android.