📋 Lesson 2.4: Custom Fields, Attachments & Card Templates

When a Card Needs Structure

So far a card holds free-form stuff: a title, a description, a checklist, some labels. That's perfect for most work. But sometimes every card on a board shares the same set of facts, and you want those facts in a consistent, comparable place. Think of a client-onboarding board where every client card should record a budget, a status, a start date, and whether the contract is signed. Cramming that into the description works, but it's inconsistent and you can't scan it.

That's what custom fields are for: they add labeled data slots that appear on every card, so the same information always lives in the same place. And because the data is structured, it shows up beautifully in the Premium Table and Dashboard views later (Lesson 4.2) — a custom field is what turns your board into something you can sort, group, and chart.

Custom Fields: Five Types

Custom fields let you add your own data slots to the cards on a board. You define a field once (name + type) and it becomes available on every card. Trello gives you five types, each suited to a different kind of value:

• Text — free text: a client name, a reference number, a URL you want visible.
• Number — a numeric value you might compare: a budget, a story-point estimate, a quantity.
• Dropdown — pick one from a preset list: a status (Prospect / Active / Paused), a tier, a region.
• Checkbox — a yes/no flag: "Contract signed?", "Invoiced?", "Approved?"
• Date — a date that isn't the card's due date: a kickoff date, a renewal date.

Where custom fields come from — and the honest plan picture

Custom fields started life as a Power-Up and are now a first-class feature. Enabling and using the full Custom Fields feature is a Standard capability (and up). On the Free plan you can still add the Custom Fields Power-Up in a more limited way, but the reliable, full experience — multiple fields, showing them on the card front — lands at Standard. As always, plans shift; this is accurate as of early 2026, so check trello.com/pricing for the current line.

Showing fields on the card front

A great touch: you can choose to display a custom field on the front of the card, right on the board, not just inside it. A budget number or a status badge sitting on the card face means you read it without opening anything — the same at-a-glance win labels give you, but for real values.

The 💲 budget and Status values on each card face are custom fields shown on the front — you read the money and the stage without opening a single card.

Attachments, Links & Storage

A card should hold everything you need to do the work — including the files and links it refers to. Click Attach on a card and you can add:

• A file from your device — a PDF contract, an image, a spreadsheet.
• A link (URL) — paste any web address; Trello often shows a rich preview.
• From a cloud service — Google Drive, Dropbox, OneDrive, or Box, so you link the live document instead of uploading a copy that goes stale.

The storage limits — honestly

This is one of the few places the free plan has a real ceiling, so let's be precise. As of early 2026:

• Free — unlimited number of attachments, but each individual file is capped at 10 MB.
• Standard — the per-file limit jumps to 250 MB, room for most documents, decks, and images.
• Premium and Enterprise — the same generous 250 MB per file, plus more admin control.

Notice what's not limited on Free: you can attach as many files as you want; only the size of any single file is capped. And there's a neat way around the cap that costs nothing —

Link previews & covers

Paste certain links — a Google Doc, a YouTube video, a design file — and Trello unfurls them into a rich preview with a title and thumbnail instead of a raw URL. You can also promote an attached image to be the card's cover (which you met in Lesson 2.1), turning a plain card into a visual one. Attachments even show as a little 📎 3 badge on the card front, so you know at a glance which cards carry files.

Attaching Cards & Boards

Here's a trick people miss: you can attach one Trello card to another, or attach a whole board to a card. Paste a card's link into another card's Attach box and Trello recognizes it, creating a live link that shows the other card's title, list, and status. It's how you connect related work without duplicating it.

A few ways this pays off:

• Link a dependency. "This card is blocked by that card" — attach it so the connection is one click, not a note in the description.
• Point to a home base. Attach a project's main board to each related card so people can jump to the big picture.
• Gather the pieces. On a "Launch" card, attach every sub-task card so the whole campaign is navigable from one place.

Card Templates: Stop Repeating Yourself

Some cards you build over and over with almost the same content: every new client needs the same onboarding checklist; every blog post needs the same production steps; every bug report needs the same fields. Rebuilding that from memory each time is slow and you'll forget a step. A card template solves it: you design the card once, mark it as a template, and then create fresh copies from it in a click — checklist, labels, custom fields, and description all pre-filled.

How templates work

Any card can become a template. Open the card, and in its menu choose "Make template." A template card gets a distinctive look and, instead of the usual options, shows a "Create card from template" button. Press it and Trello makes a normal, editable copy — the template itself stays pristine for next time. You choose which parts copy over (the checklist yes, the specific due date maybe not).

The Templates list convention

The tidiest way to organize templates is to keep a dedicated Templates list on your board — often the last list, sometimes tucked to the side — that holds nothing but your blueprint cards. Everyone knows where to find them, and they never clutter your working lists.

The 📋 Templates list on the right holds blueprint cards (marked here in purple). You press "Create card from template" on one, and a ready-to-go copy appears in your working lists — checklist and fields already filled in.

🎯 Project: A Client-Onboarding Template

Let's build something you'll genuinely reuse: a card template for a repeating task. We'll use "New Client Onboarding," but if that doesn't fit your life, pick any task you do repeatedly — publishing a blog post, planning a trip, filing an expense report — and the steps are identical.

Template card: "New Client Onboarding"
  Checklist "Onboarding steps":
    [ ] Send welcome email
    [ ] Collect brand assets
    [ ] Sign contract
    [ ] Set up shared folder
    [ ] Schedule kickoff call
    [ ] Add to invoicing
  Custom fields:
    Budget      (Number)
    Status      (Dropdown: Prospect / Onboarding / Active)
    Kickoff     (Date)
    Contract signed?  (Checkbox)
  Description: a short "how we onboard" note

→ "Make template" → then "Create card from template"
   each time a new client arrives.

Best Practices for Fields, Files & Templates

✅ Do's

• Use dropdowns for known options. They keep status and category data consistent and chart-ready.
• Link big files from the cloud. It dodges the size cap and keeps the latest version on the card.
• Keep a Templates list. One tidy home for every blueprint card, out of your working lists.
• Template the structure, not the data. Leave client-specific values blank; fill them per copy.

❌ Don'ts

• Don't custom-field everything. If a value only matters on one card, the description or a label is enough.
• Don't upload files that live better as links. A stale copy on a card is worse than a live cloud link.
• Don't expect card links to trigger actions. Attaching a card is a bookmark, not automation — that's Butler's job (Module 5).

📓 Learning Journal

📝 Lesson Summary

🎉 What You've Accomplished

Your cards just grew up. They now hold structured data you can compare, files and links that keep the whole context in one place, and — best of all — you've built a template that does ten minutes of setup for you every time it's used. That's the first taste of Trello doing work for you instead of you doing all the work in Trello. It's exactly the mindset Module 5's automation runs with.

❓ Common Questions at This Stage

🔭 Looking Ahead

That's Module 2 complete — you can now make a single card genuinely powerful. Next module zooms back out to the board: designing lists and stages that model your real workflow, and using WIP limits to actually finish things instead of juggling them. It's where Kanban stops being theory and becomes your system.

✅ Before the Next Lesson

• Keep your Templates list and onboarding template — you'll reference templates again in Lesson 7.3
• Note which custom fields (if any) needed Standard, so you can weigh an upgrade honestly
• Write your Learning Journal entry for this lesson

📚 Additional Resources

• Trello Guide — official getting-started docs
• Trello Support — custom fields, attachments & templates
• trello.com/pricing — custom fields & attachment limits by plan