Build a Form With Calculations: an Instant Price Quote in 15 Minutes

Open the instant estimate templateDownload the price formula worksheet (PDF)

What a calculated field does

A calculated field is a question the visitor never answers. It works out a number from the other answers and shows it as they go: a price for a quote form, a score for a quiz, a total for an order. In the form builder it is the Calculation question type. The result updates live while the form is filled in, is stored with the answers, and can be formatted as money or hidden from the visitor entirely when you only want it in your results.

Instant estimates help both sides. The visitor learns whether you are in their price range before they wait for a reply, and you receive enquiries from people who have already seen a number. A calculated estimate is not a binding quote, so say "estimated" in the label and confirm the exact price yourself.

Most form tools handle this somewhere; Jotform, for example, uses a Form Calculation widget, and Tally lists calculations on its free plan. The method below uses the builder's own calculation question, which is on the free plan too.

How the formula works

A formula refers to other questions by their key in curly brackets, such as {hours}. In the question's settings, the formula box has a chip for each earlier question; clicking one inserts its key, so you rarely type keys by hand.

Each question type gives the formula a number:

• A number question gives the number typed.
• A choice question gives the points you set on the chosen option. Points are how you attach a rate or a price to each option.
• Yes/No gives 1 for Yes and 0 for No.
• Checkboxes give how many boxes are ticked.

You can use + − * / and brackets, comparisons, and the functions round(x, d), min, max, abs, floor, ceil and if(condition, a, b). A formula that cannot be worked out counts as 0 rather than breaking the form, which is exactly why testing matters: a typo shows up as a price of zero, not an error message.

The worked example: hourly rate with a rush fee

The Instant price estimate template asks three questions on page one: how many hours, which package, and whether it is needed within 48 hours. The Standard package carries 75 points and Premium 110, standing in for hourly rates. The estimate's formula is:

round({hours} * {package} * if({rush} = 1, 1.25, 1), 2)

In words: hours times the package rate, times 1.25 if rush was answered Yes, otherwise times 1, rounded to two decimal places. For 4 hours of Premium with rush, that is 4 × 110 × 1.25 = 550. For 4 hours of Standard without rush, 4 × 75 × 1 = 300.

Page two, "Where should we send it?", collects name, email and phone. People see the estimate before they give contact details, which is the honest order: they decide whether the number suits them, then whether to hear from you.

Step by step: make it your price

1. Open the template

Open the free form builder with the Instant price estimate template (the button at the top of this post does this).

2. Set your rates

Select the Package question. In the settings panel, each choice has a points box; enter your rate for each. Rename the options to your own packages, or add a third.

3. Edit the formula

Select the Estimated price question. Change 1.25 to your rush multiplier, or replace the whole if(…) part with a fixed fee, such as + if({rush} = 1, 150, 0). To add a minimum charge, wrap the formula in max(…, 200).

4. Add a rule for big jobs

Under Settings, Logic rules, add a rule: when Estimated price is more than a threshold you choose, show a different thank-you message, such as a promise to call within the hour. The video shows a rule like this at 1,500. The conditional logic guide explains rules in full.

5. Test five cases you priced by hand

In Preview, enter five sets of answers you have already priced on paper: the smallest job, a typical one, the most expensive combination, a rush job, and one with an optional question left empty. If the form disagrees with your paper, the formula is wrong, not the paper. The worksheet with this post has the table.

Taking payment from the calculated amount (a payment question whose amount comes from the calculation, charged through your own Stripe account) needs a paid plan. On the free plan the estimate works fully; you confirm and invoice the job yourself. To show the form on your site, see how to embed a form.

Other calculations worth building

The same pieces cover more than hourly quotes:

• Per-item pricing. A number question for quantity times a fixed price: {rooms} * 120 for cleaning, {guests} * 45 for catering.
• Add-ons. A checkboxes question gives how many boxes are ticked, so {addons} * 50 prices add-ons that all cost the same. For add-ons with different prices, use a separate Yes/No question for each and add them up: if({drone} = 1, 250, 0) + if({rush} = 1, 150, 0).
• Quiz and readiness scores. Give answer options points and add the questions together. Quizzes can show a result by score range at the end.
• Thresholds. Combine a calculation with a rule, as in step 4, to send big jobs a different message or skip a page for small ones.

Keep the visible formula simple. If the price needs more than three or four inputs, show a range ("from $300") and confirm the exact figure yourself.

Questions people also ask

Sources

• Jotform Help — Form Calculation widget
• Tally — Pricing
• Nielsen Norman Group — Website Forms Usability