Free tool

What will Claude cost to run?

If you are paying a flat monthly fee to use Claude yourself, this is not for you. This is for the other kind of bill: the one you get when a thing you are building sends questions to Claude on its own and you pay for each one.

Everyone asks what that comes to before they build the thing, and every answer online is written in units nobody bills their own time in. Answer four questions in plain words and see the monthly bill on four current Claude models, side by side, plus the two things that cut it. Everything happens on this page, and nothing you type is sent anywhere.

One go, start to finish

Think about a single question your thing asks Claude, and the answer that comes back. Answer in words, and guess. A rough guess gives you a useful number, and you can change it in five seconds once you see how much it moves.

How much do you send Claude each time? In words. A page of text is about 500 words. Include your instructions and anything you paste in with the question. How much do you want back each time? In words. A short answer is about 100, a full write-up about 1,000. Answers cost around five times what questions do, so this one matters more than it looks.

How often How many times a day? Across everybody using it. If ten people use it twenty times each, that is 200.

Two ways to pay less

Neither of these is a switch you flip. They are things whoever builds the thing has to build in, which is exactly why they are worth knowing about now rather than after. Leave them blank if neither fits.

How much of what you send is word for word the same every time? Your standing instructions, a price list, a long example, anything that does not change between one question and the next. Claude can hold on to a chunk like that and re-read it for a tenth of the price, if it is long enough and the questions keep coming. The estimate tells you whether yours qualifies. Leave blank if every question is different, and never count more than you answered above. I do not need the answers straight away. If you can live with waiting up to a day, everything costs exactly half. This suits anything that runs overnight or works through a pile of things at once. It does not suit anything a person is sat waiting on, and it is a different way of asking Claude that has to be built that way from the start. Tick it and the estimate stops counting the repeated part above, because nothing published says the two work together, and this page would rather quote you the dearer of two answers than the cheaper one.

Your estimate

This updates as you answer. Nothing here leaves your browser.

What to do with the number

The useful move is not to read it, it is to argue with it. Hit Copy, paste the whole thing to Claude, and say here is my cost estimate and here is what I am building, tell me which of these numbers I have guessed badly and what would cut the bill most. It will go after the reply length first, because that is the expensive half, and that is usually the right answer.

The second move is to run it twice. Once with the cheapest model and once with the most expensive, and see whether the gap is a rounding error or the whole business. If it is a rounding error, build on the good model and stop optimising. If it is the whole business, you have learned that before writing anything rather than after.

Why the cheap model is not always the cheap answer

A weaker model that needs two attempts costs more than a stronger one that gets it right first time, and it costs you the time spent working out why the answers are off. The number above prices one clean go. Price two goes on the cheap model against one on the good one before you decide.

Every figure here is the dearer answer

Being told a thing costs $5 and then billed $10 is the one outcome worth designing against, so this estimate is built to miss in the other direction. Where the published rules are clear it follows them exactly. Where they leave a question open it takes the more expensive answer, and every amount on screen is rounded up rather than down. Aim at these numbers and be pleased when the real bill lands under them.

Three places that shows up, in case you want to argue with any of them. Ticking the last box on the form drops the repeated-words saving entirely, because nothing published confirms the two work together. A month is counted as 30.4 days, the real average, not the 30 that most calculators round to. And the repeated words are charged at the full first-time price a dozen times a day rather than once, on the grounds that real traffic has quiet spells and Claude only holds on to them for five minutes.

The one thing that can still land above the estimate is what you are sending. These figures assume plain English. Code, tables and other languages all cost more per word, so treat the number as a floor if that is what your questions are made of.

How to tell your real bill matches

Once anything is actually running, the usage page in your Claude account shows what you truly spent. Compare it to this after a week. If it is miles off, the thing that is wrong is almost always how much you thought you were sending, because the instructions and the pasted-in material add up faster than anyone expects.