Data analysis for high-school science

From pencil lines to honest fits.

Plot45 turns the numbers from your experiment into a clean, honest graph — best-fit curves, real uncertainty, and export-ready figures — right in your browser. Nothing to install. No account.

Launch Plot45 See it work

Free. Runs offline · your data never leaves your device.

m — R² — n 7

Sketching

Fig. 1 One dataset, developed — a raw pencil plot resolves into a fitted line, the way Plot45 does it in seconds.

1Type or paste your readingsStraight from a spreadsheet, into the table.

2Pick a fit — it solves instantlyLine or curve, with a real R².

3Export a clean figureSVG, PNG or print, lab-report ready.

What it does

The graph your lab report needs — with the honesty your teacher is looking for.

Three things separate a plot that earns the marks from one that doesn't: the right fit, uncertainty done properly, and a figure clean enough to hand in. Plot45 does all three.

Fig. 2 · Curve fitting

Five fit models. One honest R².

Drop in your points and Plot45 finds the line — or the curve. It fits the model you choose and reports how well it really matches, never an inflated number.

LinearStraight-line fits with gradient and intercept, read straight off the chip bar.
CurvesExponential, logarithmic, power and quadratic — the shapes real experiments make.
R²Computed in real data space, so the fit quality you see is the fit quality you have.

Try a fit

Fig. 2The same plot, fitted four ways — the active model and its R² update live.

Fig. 3 · Uncertainty

Error bars, and the gradient they really allow.

This is the part most tools skip. Plot45 draws your error bars, then finds the steepest and shallowest lines that still pass through every one — the marked method for the uncertainty in your gradient.

BarsPer-point error bars on x and y, sized from your own uncertainties.
Max/minThe steepest and shallowest lines through every bar, drawn for you.
ResultA gradient reported as m = m ± Δm — exactly how it's marked.

See the band

m 2.41 Δm 0.12 method max–min

Fig. 3Error-bar crosses with the steepest and shallowest lines that still thread them all.

Fig. 4 · Export

Lab-report ready, the moment you're done.

No screenshots, no cropping. Take the finished graph out as a crisp vector, a clean raster, or straight to print — labelled, scaled, and ready to drop into your write-up.

SVGCrisp vector that stays sharp at any size, in any document.
PNG2× raster for a quick, clean drop-in.
PrintA print / PDF view of just the graph — nothing else on the page.

Export a graph

file plot45-ohms-law format SVG

Fig. 4One finished plot, three ways out — the format cycles SVG, PNG, print.

Day or night

The whole instrument, in the dark.

Light on paper by default; easy on the eyes at midnight. Same precise plot, inverted chrome — the figure itself stays on clean white, wherever you work.

The Plot45 workbench in dark mode: a white plot area with a fitted line and capped error bars, flanked by the stage rail, the best-fit results bar, the data view, and the Canvas inspector.

Also inside

The small things that make it a tool, not a toy.

Paste from a spreadsheet

Copy a block of readings from Sheets or Excel and drop it straight into any cell. Rows grow to fit.

Multiple variables

Plot several dependent variables at once, each auto-styled with its own marker and a tidy legend.

Draggable equations

Pick up any equation label and place it exactly where it reads best on the plot.

Worked examples

Load real datasets — Ohm's law, a pendulum, capacitor discharge — and see the method end to end.

Autosaves locally

Your work is kept in the browser as you go. Close the tab, come back, pick up where you left off.

Light & dark

A calm paper light mode and a low-glare dark mode. The plot stays crisp in both.

For schools & departments

Bring your whole class's lab work into the future.

One method, taught once, applied consistently — from the first practical to the final write-up. Nothing for IT to install, nothing for students to lose.

Open Plot45

01 Nothing to install or maintain

A single static page that loads in any modern browser — on the lab desktops, the library iPads, or a phone on the bus home.

02 Private by design

Student data is held on the device, not on a server. No accounts to manage, no records to safeguard.

03 One consistent method

Every student handles uncertainty the same marked way — error bars and the max/min gradient — so results are comparable and fair.

04 Works with what you have

No licences per seat, no plug-ins, no version drift. It simply works, the same way, everywhere.

Ready when you are

Plot your first graph
in the next minute.

No sign-up, no download, no setup. Open Plot45 and start typing.

Launch Plot45 — free

Runs entirely in your browser. Your data stays with you.