Move from a $20\/month plan to a $40\/month plan on day 17 of a 30-day cycle and you will be charged one of four different amounts depending on the provider: $11.33, $40.00, $0.00, or $11.67. The machine is identical in all four cases. What changes is the proration formula in the billing panel — and on a $40 plan the difference between the cheapest and most expensive formula is more than $28 for a single click. Below are the arithmetic behind each model, the cycle dates that minimise the invoice, and the traps that make an upgrade cost a full month when it should have cost a third of one.<\/p>\n\n
Almost every budget provider uses one of four methods. Calendar-day proration<\/strong> is the most common: unused days are credited at plan price divided by days in the billing month, and the new days are charged at the same basis. On a 30-day month the daily rate is $0.667 for the $20 plan and $1.333 for the $40 plan. With 17 days left the credit is 17 × $0.667 = $11.33 and the charge is 17 × $1.333 = $22.67, so the invoice shows $11.33.<\/p>\n\n No proration<\/strong> means you pay the full new price now with no credit; the same switch costs $40.00 and silently forfeits $11.33. Next-cycle billing<\/strong> charges nothing today but withholds the new spec until renewal — a real cost if the upgrade was triggered by a memory problem. Hourly metering<\/strong> publishes an hourly rate (often monthly price ÷ 730) and bills hours used, which makes the invoice unambiguous and usually lands within a few cents of calendar-day proration.<\/p>\n\n The confirmation screen in most panels shows the exact amount due today. Multiply remaining days by the difference in daily rates first and compare: if the number on screen equals the full new plan price, you are on a no-proration provider; if it is zero, you are on next-cycle billing. Both are legal and disclosed in the terms, but only one of them prices a resize honestly.<\/p>\n\n Prorated cost is linear in remaining days, so the same upgrade bought on day 2 and on day 27 differs by a factor of roughly 13. Take a $40 plan replacing a $20 plan on a 30-day cycle: the prorated invoice on day 27 is 3 × $0.667 = $2.00. On day 2, with 28 days left, it is $18.67. If the workload is a quarterly batch or a one-off launch, buying late in the cycle and downgrading at the next renewal is dramatically cheaper than buying early.<\/p>\n\n The exception is a genuine capacity emergency: if a 1 GB box is swapping through 30% of the day, paying $18.67 on day 2 is far cheaper than a week of 3-second page loads. The rule that resolves the tension is to upgrade when the metric has been sustained for five days, and to pick the cycle position only when the trigger is forecast rather than observed.<\/p>\n\n Downgrades prorate in the same direction but with worse economics. Some panels apply the credit to the next invoice instead of issuing a refund, and many cap the credit at the remaining balance of the current cycle. Downgrade on day 29 and you receive one day of savings — about $0.33 on the $40→$20 move — while losing 29 days of the capacity you already paid for.<\/p>\n\n Schedule downgrades for days 1–5 of the cycle. At that point the credit is close to the full monthly difference ($20.00) and the new, smaller spec has a full month to prove it is sufficient. Take a snapshot before downgrading, because most providers cannot restore capacity instantly if the smaller plan turns out to be undersized: a re-upgrade typically means a rebuild plus a prorated charge, and 20–40 minutes of downtime.<\/p>\n\n If you prepaid $64.80 for a year at $5.40\/month and upgrade in month 8, the correct credit is 4 months × $5.40 = $21.60 against the new annual rate. Many providers instead compute the credit from the list monthly rate and the charge from the new list rate, which erases your prepayment discount. The loss equals the discount multiplied by the remaining fraction — small on a $5 plan ($2.40), but $19.20 on a $48-per-month annual plan that saved 10%.<\/p>\n\n Ask two questions in writing before upgrading a prepaid plan: is the credit computed from the amount paid or from list price, and does the new plan restart or preserve the annual term? If the answers are ambiguous, stay monthly until your sizing is stable. A 10% annual discount is rarely worth $20–$40 of lost flexibility on a mid-range plan.<\/p>\n\n A single resize is pocket money; resizing three or four times a year is a budget line. Suppose you start at $10, move to $20 in month 4, $40 in month 7, and back to $20 in month 11 — a common growth-then-retrench path for a side project that had one busy quarter. Under calendar-day proration the total invoiced is $10×3 + $20×3 + $40×4 + $20×2 = $290. The same capacity bought as a flat $20 plan for twelve months would be $240; as a flat $10 plan, $120 but with three months of inadequate memory.<\/p>\n\n The comparison to make is not prorated versus flat, but prorated versus the flat plan you would have needed anyway. If the peak month genuinely requires 4 GB, the $40 tier for four months is the honest cost. What proration buys you is the ability to pay for peak capacity only during the peak — provided you remember to step down. Set a calendar reminder for day 2 of the following cycle every time you upgrade; the forgotten downgrade is the most common way a $10 project becomes a $30 subscription.<\/p>\n\n None of these are hidden in bad faith — they are in the terms of service, just not on the upgrade button. Ten minutes in the billing section before your first resize is the cheapest audit you will run all year; the renewal-adjusted pricing columns<\/a> lists renewal dates and billing terms for the plans we track, which makes the arithmetic above a two-minute exercise.<\/p>\n\nModel<\/th> 21 days used \/ 9 left<\/th> Upgrade $20 to $40<\/th> Invoice today<\/th> Unused value lost<\/th><\/tr><\/thead> Calendar-day<\/td> $14.00 used<\/td> $12.00 for 9 days<\/td> $10.00<\/td> $0.00<\/td><\/tr> No proration<\/td> $14.00 used<\/td> $40.00 full month<\/td> $40.00<\/td> $6.00<\/td><\/tr> Next-cycle<\/td> $14.00 used<\/td> Old spec until renewal<\/td> $0.00<\/td> 9 days of capacity<\/td><\/tr> Hourly (730 h\/mo)<\/td> 168 h × $0.0274<\/td> 72 h × $0.0548<\/td> $3.94<\/td> $0.00<\/td><\/tr><\/tbody><\/table><\/figure>\n\n Why the Cycle Date Matters More Than the Plan You Choose<\/h2>\n\n
Upgrade day<\/th> Days remaining<\/th> Prorated invoice ($20 to $40)<\/th> Share of full month<\/th><\/tr><\/thead> Day 2<\/td> 28<\/td> $18.67<\/td> 46.7%<\/td><\/tr> Day 10<\/td> 20<\/td> $13.33<\/td> 33.3%<\/td><\/tr> Day 17<\/td> 13<\/td> $8.67<\/td> 21.7%<\/td><\/tr> Day 24<\/td> 6<\/td> $4.00<\/td> 10.0%<\/td><\/tr> Day 29<\/td> 1<\/td> $0.67<\/td> 1.7%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n Downgrades: Where the Credit Quietly Disappears<\/h2>\n\n
Prepaid Annual Plans Break the Formula<\/h2>\n\n
Annual Build-Up: What Proration Costs Over a Year<\/h2>\n\n
Five Traps That Inflate the Invoice<\/h2>\n\n
A Ten-Minute Upgrade Checklist<\/h2>\n\n