Embedding, the robust way
Five ways to drop a calculator into a page
The script embed (<instacalc>) is elegant, but the
iframe embed is the bulletproof one: it runs the whole
calc sandboxed on instacalc.com, so
there's no shared JavaScript and nothing to break on your side. Here's the
full range of iframe URLs you can point at.
1. A saved calc, by ID
The canonical form is /embed/<id>. This loads a stored
calc — the same image "Copy embed code" gives you:
2. A blank calculator
Point an iframe at bare /embed/ to drop a fresh, empty
calculator into your page — handy when you want readers to type their own
math from scratch:
3. A formula, defined entirely in the URL
No saved calc needed — put the math in the URL after /embed/=.
This one computes a 30-year mortgage payment on a $400k loan at 6.5%:
4. A quick one-liner
The URL-defined form is great for tiny, self-explanatory calcs. Annual coffee spend, inline:
5. The legacy suffix form (still works forever)
Old embeds in the wild use /<id>/embed. That's a
permanent redirect to the canonical /embed/<id>, so
historical iframes keep resolving:
Every iframe above runs the calc on instacalc.com and computes
live — they're the most robust embed path. The inline
<instacalc> script embed (see the
mortgage post) is lighter-weight but
relies on loading the engine into your page.
Sizing tip: the iframe doesn't scroll — it shows exactly
its height, so set one tall enough for all the calc's rows
(a 12-row calc needs ~680px; a one-liner ~220px). Pick the height to fit
the calc you're embedding.