Line Graph Maker
Line and area charts on a real date axis, with notes and moving averages.
First column: dates, numbers or labels for the x axis. Other columns: numbers, one column per line.
Chart
Arrow keys move from value to value; up and down switch series; Escape hides the tooltip.
Chart data as a table
About the Line Graph Maker
Paste a table with dates (or numbers, or labels) in the first column and one column per series, and see it as a line graph on a true date axis: points are placed by their real dates, so uneven gaps between dates look uneven, and the ticks follow the calendar (days, months, quarters, years). You choose whether 04/10/2026 means 4 October or 10 April.
Draw lines or areas (stacked or 100% stacked), straight, smooth or stepped. Missing values leave a gap rather than a fake zero. Add notes at dates (“Price cut”), a reference line, a log scale for growth, and a moving average to see the trend through day-to-day noise. Download a PNG (up to 4×) or SVG. Your data stays in your browser.
How to use it
- Paste your data into Your data: dates in the first column, a column of numbers per line. Or choose Open file for a CSV or Excel sheet.
- Check Dates like 04/10/2026 are — day first (DD/MM) or month first (MM/DD). ISO dates such as 2026-10-04 are never ambiguous.
- Under Line chart, pick the x column, tick the series, and choose lines, areas or stacked areas and the line shape.
- Optionally add a moving average, a log scale, a reference line or notes at dates (one per line:
2025-11, Festive sale). - Set titles and the number format, then Download PNG or SVG, copy the image or copy a share link.
Examples
Month Sales 2026-01 120 2026-02 2026-03 150
A line with a gap at February (or joined across it, if you choose “Connect”)
Notes: 2025-11, Festive sale
A dashed vertical line at November 2025 labelled “Festive sale”
Dates with commas work too: Oct 4, 2026, Launch.
9, 8, 9, 12, 9, 12, 11, 7, 13, 9, 11, 10
—, —, 8.667, 9.667, 10, 11, 10.667, 10, 10.333, 9.667, 11, 10
The single moving average example from the NIST/SEMATECH e-Handbook §6.4.2.1: each value is the mean of that point and the two before it.
Common uses
- Sales, orders, website visits or prices over time.
- Comparing several series (products, cities, channels) on one date axis.
- Seeing a trend in noisy daily data with a 7-day or 30-day moving average.
- Showing exponential growth — doubling looks like a straight line on a log scale.
- Plotting readings from an experiment against a numeric x (time in seconds, temperature).
Dates: DD/MM or MM/DD?
A date such as 04/10/2026 is 4 October in India and the UK but 10 April in the US. If any date in the data has a day above 12 (25/10/2026), the order is clear and is used automatically; otherwise dates are read day first and the page says so — switch Dates like 04/10/2026 are to month first if your data is American. ISO dates (2026-10-04), month names (4 Oct 2026, Oct 2026) and quarters (Q3 2026) are always clear. Times (2026-10-04 14:30) are kept, and a column of times alone (09:00, 09:30) is plotted across one day.
Moving averages
A moving average smooths short-term ups and downs. Following the NIST/SEMATECH e-Handbook of Statistical Methods (§6.4.2):
- Trailing (single moving average, §6.4.2.1): the mean of the latest N points, M = (Xₜ + Xₜ₋₁ + … + Xₜ₋ₙ₊₁) / N. It starts at point N and lags the data a little.
- Centred (§6.4.2.2): the mean of the N points around each point. For an even N there is no middle point, so two neighbouring N-point averages are averaged (a “2×N” average).
The window counts points (rows), not days — with irregular dates, a 7-point average is not a 7-day one. A point gets an average only when every point in its window has a value, so a gap in the data makes a gap in the average.
Gaps, zero and log scales
- Missing values: “Leave a gap” is the honest default; “Connect” joins the neighbours (fine when a value simply was not recorded); “As zero” draws 0, which is right only when nothing happened. Stacked areas cannot leave a gap: a date where one series is empty is left out and the areas join across it (or it is drawn as 0 with “As zero”).
- Start at zero: lines do not have to start at zero — tick it when the size of the change matters more than its shape. Areas always start at zero.
- Log scale: equal distances on the axis stand for equal ratios, so 10, 100 and 1,000 are evenly spaced. Use it for growth over several orders of magnitude; values of zero or below cannot be shown and are left out (the page says how many).
- Smooth lines use monotone curves that pass through every point without overshooting, so they never invent a peak that is not in the data.
Limitations
- Up to 10,000 points per series and 60 columns.
- Times are shown as written, without converting time zones; a time with a zone (Z or +05:30) is shown in UTC.
- Moving averages are simple (equally weighted) averages over points; exponential smoothing is not included.
- One y axis per chart: for two series with different units use the Chart Maker’s combo chart with a second axis.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
How do I make a line graph with dates?
Put the dates in the first column and the values next to them, then paste the table. The x axis becomes a date axis: points are spaced by their real dates and the labels follow the calendar. Choose whether dates are day-first or month-first under Dates like 04/10/2026 are.
How do I plot several lines on one graph?
Give each line its own column of numbers. Each ticked column becomes a line with its own colour and a legend entry.
What happens to empty cells?
By default the line stops and starts again, leaving a gap, so a missing value is not mistaken for zero. Choose Connect to join across it, or As zero to draw it as 0.
How is the moving average calculated?
Trailing: the mean of the last N points, as in the NIST/SEMATECH e-Handbook §6.4.2.1 (with 9, 8, 9 the 3-point average is 8.667). Centred: the mean of N points around each point; an even N averages two neighbouring averages (§6.4.2.2).
Can I add labels or notes at certain dates?
Yes — under Notes on the x axis, write one per line: the date, a comma and the note, e.g. 2025-11, Festive sale. Each note draws a dashed vertical line with its text.
Is my data uploaded?
No. Everything is drawn in your browser. A share link carries the data inside the link after the “#”, which browsers never send to a server.