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Monthly Sales Forecast Calculator

October 2026 12 min read

Forecast next month sales from daily run rate, selling days and expected lift. Free, instant, no sign-up.

Know next month before it starts

Enter daily run rate and selling days once — get baseline, forecast and the exact lift dollars instantly.

Run-rate mathLift isolatedBuy-ready output
Best window for a fresh daily base
14 days
Source: Planning practice
Typical lift from established promos
15-40%
Source: Industry benchmarks
Achievable monthly forecast error
5-10%
Source: Forecasting literature
Standard selling-day count for full months
30 days
Source: Retail practice

Interactive Calculator

Enter your numbers — every result below updates instantly. No sign-up, free forever.

Inputs

Average daily sales ($)
Selling days in month
Expected lift (%)

Results

Baseline month$54000.00
Forecast month$58320.00
Lift dollars$4320.00
Implied daily target$1944.00

Visual Cost & Profit Breakdown

See exactly where every dollar of your selling price goes — costs, fees, and the profit you keep.

Bars are proportional to the headline figure — segments vs profit.

E-commerce Statistics That Shape Smart Pricing

Benchmarks from widely-cited industry research. Use them to sanity-check your margins, fees, and conversion assumptions.

Best window for a fresh daily base
14 days
Source: Planning practice
Typical lift from established promos
15-40%
Source: Industry benchmarks
Achievable monthly forecast error
5-10%
Source: Forecasting literature
Standard selling-day count for full months
30 days
Source: Retail practice

Pricing Plans Compared: Which Strategy Fits Your Store?

Three proven pricing plans for online sellers. Match the plan to your stage, then plug its margin target into the calculator above.

Starter Plan — Single-Rate

Best for: new stores and quick targets

  • Price rule: One growth rate compounded monthly with a flat seasonal factor
  • Margin target: 10–20% annual growth
  • Fees: Blended fees in one variable line
Most popular

Growth Plan — Seasonal + Cohort

Best for: scaling stores with 12-mo history

  • Price rule: Monthly compounding with per-month seasonal factors and repeat-order uplift
  • Margin target: 20–40% annual growth
  • Fees: Channel-split fees with returns reserve

Scale Plan — Scenario Range

Best for: brands and Q4 peaks

  • Price rule: Base + upside + downside cases with lead-time inventory bridge
  • Margin target: 40%+ with peak coverage
  • Fees: Full fee stack plus storage and ad TACOS

Formulas & How to Use This Calculator

Monthly forecast

Forecast = DailySales x Days x (1 + Lift)

Daily target

DailyTarget = Forecast / Days

How to use — step by step

  1. Enter average daily sales from the last 14 to 28 days.
  2. Set selling days, usually 30, fewer for seasonal closures.
  3. Set expected lift from promos, launches or seasonality.
  4. Read the forecast and the implied daily target for the team.
  5. Convert the forecast into unit buys using current AOV.
  6. Revisit mid-month and reforecast with actuals to date.

Worked Examples

Real numbers, fully worked — copy the pattern for your own products.

Example 1 — Normal month

Inputs

Daily $1,800, 30 days, lift 8%

Math

54,000 x 1.08 = $58,320

Result

About $58,320 forecast with a $1,944 daily target

Example 2 — Promo month

Inputs

Daily $2,000, 30 days, lift 25%

Math

60,000 x 1.25 = $75,000

Result

About $75,000 — pre-buy inventory for the extra $15,000

Example 3 — Short month

Inputs

Daily $1,500, 28 days, lift 0%

Math

1,500 x 28 = $42,000

Result

About $42,000 flat — staff and buy to the lower day count

Advanced Education: Master E-commerce Pricing

Beyond the basics — the concepts professionals use to price for profit across channels, seasons, and competitors.

Daily run rate beats monthly averages

A 28-day average of daily sales reacts to trend changes weeks before a monthly total does. Professionals reforecast from the freshest 14 days, not the last calendar month. Stale bases are the top cause of missed monthly forecasts.

Lift needs an owner

Every lift point should name its driver: 10 points from the spring promo, 8 from the new bundle, 5 from paid scale-up. Unowned lift evaporates under questioning, while owned lift can be tracked and repeated.

Translate dollars to days of cover

Divide on-hand inventory value by the implied daily target to get days of cover. If cover falls below lead time plus safety buffer, the forecast is really a purchase order. This translation turns a finance number into a warehouse action.

Mid-month reforecasts save quarters

At day 15, replace the forecast with actuals to date plus daily run rate times remaining days. This single habit catches slippage early enough to add a promo weekend or trim buys.

Platform Playbooks: Amazon, Shopify, Etsy & eBay

Fee structures differ by channel — here is how to adapt one base price per marketplace without losing margin.

Amazon

Forecast with referral (often ~15%) plus FBA storage seasonality: Q4 uplift 1.3–2x needs 60–90 days cover ordered one lead time early.

Shopify

DTC forecasts compound cleaner without marketplace take; model email repeat uplift 10–25% separately from cold-traffic conversion.

Etsy

Small-base forecasts swing on few heroes; use 50% safety cover and sibling-SKU velocity for launches until 60 days of data.

eBay

Auction and promoted-listing mix shifts conversion fast; reforecast whenever promoted share moves 20%+ or format mix changes.

Glossary: Pricing Terms Explained

Run rate
Daily sales pace extended across the month.
Lift
Expected percentage gain over baseline from known drivers.
Days of cover
On-hand inventory divided by daily sales pace.
Reforecast
Updating the forecast mid-period with actuals to date.

Common Pricing Mistakes & Pro Tips

Mistakes that kill margin

  • Using last month total as the base when the last 14 days already trend differently.
  • Adding lift without naming the promo or channel that produces it.
  • Forgetting fewer selling days in short months and holiday closures.

Pro tips to grow profit

  • Refresh the daily base every Monday from trailing 14-day sales.
  • Give the team one daily target number and post actuals beside it.
  • Reforecast at mid-month with actuals plus run rate times days left.

Who Should Use This Calculator?

  • ▸ Store managers setting next month targets and staffing
  • ▸ Buyers converting forecasts into unit purchase orders
  • ▸ Marketers sizing promo lift needed to hit the number
  • ▸ Founders sanity-checking monthly goals before committing spend

Related E-commerce Calculators

Keep optimizing — every tool below links directly into this pricing workflow.

Frequently Asked Questions (10)

Long-tail answers: each question targets a real Google search about monthly sales forecast calculator — click to expand.

How do I forecast next month sales?
Multiply average daily sales by selling days, then by one plus expected lift: $1,800 x 30 x 1.08 is about $58,320. Use the last 14 to 28 days for the daily rate and name the driver behind every lift point.
How many selling days should I use?
Use 30 for full months, actual open days for seasonal closures, and 28 for February planning. If weekends run hotter, use a weighted daily average rather than a flat count.
What lift should I assume for a promo month?
Established promos lift 15 to 40 percent, new promos 5 to 15 percent, and sitewide sales with email support 20 to 35 percent. Anchor to your last comparable event and adjust for discount depth and list size.
How do I turn the forecast into inventory?
Divide the dollar forecast by AOV for units, then compare against on-hand plus inbound minus lead-time demand. Order the gap plus safety stock. A $58,320 forecast at $65 AOV means about 897 units.
Should weekends count differently?
Yes if weekend volume differs by more than 20 percent from weekdays. Compute separate weekday and weekend daily rates and multiply by their day counts. Blended rates underbuy Saturday peaks and overbuy Tuesday troughs.
How accurate are monthly sales forecasts?
Within 5 to 10 percent when the daily base is fresh and lift drivers are named. Error doubles when the base is older than 30 days or lift is a round-number guess. Mid-month reforecasts halve remaining error.
What if daily sales are trending down?
Use the most recent 7-day average as the base instead of 28 days, and set lift to zero until the cause is fixed. Forecasting growth on a declining base compounds the miss. Fix conversion or traffic first.
Can I forecast by category?
Yes and you should: run the same math per category with its own daily rate and lift, then sum. Category forecasts expose which lines carry the month and which need promo support.
How do returns affect monthly forecasts?
Multiply the gross forecast by one minus the return rate for net revenue planning. At 8 percent returns, a $58,320 gross month nets about $53,654. Buy packaging and plan cash on net, not gross.
What daily target should I give the team?
Divide the forecast by selling days: $58,320 over 30 days is $1,944 per day. Post it daily with actuals so the team sees the gap while there is still time to act.

Resources & Authoritative References

Further reading

Authoritative sources

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Last updated: October 2026 · Free forever · No sign-up · Part of E-commerce Calculators at Atlascalcs.com